Explainer
Javelin rules explained: what makes a throw valid or a foul
The javelin rules that decide a throw: head-first landing, the 28.96 degree sector, when you may leave the runway, and the implement specification.
By CricketTaken EditorialPublished Explainer19 min read
A javelin lands beyond everyone else's mark and the flag goes up red. The crowd boos. The thrower knew before the implement landed, because they watched it go flat in the air about twenty metres out, and there is nothing in the rulebook that gives credit for distance travelled by an object that arrived sideways.
That is the single most misunderstood thing about the javelin rules, and it is usually explained wrongly in the other direction: people say the javelin has to stick in the ground. It does not, and it never has under the current rules. What it has to do is arrive head first.
The gap between those two statements is where most of this event's officiating lives, and it is a good place to start, because almost every other rule in the javelin follows from the same problem: an implement that flies two thirds the length of a football pitch has to produce a mark that two officials can identify, agree on and measure, in front of a stadium, within seconds.
- 8Radius of the throwing arc, in metres
- 4Width of the runway, in metres
- 28.96Landing sector angle, in degrees
- 34.92Sector angle for the other three throws, in degrees
What the javelin rules count as a valid throw
Four conditions, and they are short enough to quote in substance.
The javelin is held at the grip, with one hand only. It is thrown over the shoulder or the upper part of the throwing arm. It may not be slung or hurled, and non-orthodox styles are not permitted.
Then the clause that gives that last sentence teeth: until the javelin has been thrown, the athlete may not at any time turn completely around so that their back is towards the throwing arc.
This is the rule that keeps the javelin a linear event while the shot, discus and hammer have all become rotational. It is not a stylistic preference. A spinning delivery generates far more implement speed, and a spinning delivery of a two and a half metre metal-tipped shaft, on a runway pointed into a stadium, is a different proposition from a spinning delivery of a shot inside a cage. The rule keeps the thrower facing the sector for the entire approach and release, which means the only place the implement can go is where everybody is already looking.
There is a sensible note attached: the restriction applies to the run-up and the act of throwing. Walking back to the start of the runway before an attempt, or after interrupting one, does not count as turning around.
The fourth condition is the landing, and it deserves its own section.
The landing rule, and the myth about sticking in
A throw is valid only if the metal head strikes the ground before any other part of the javelin.
That is the whole rule. Not "sticks in". Not "remains upright". The head arrives first, and after that the implement can bounce, skid, fall flat or roll into the next postcode without affecting the verdict.
The wording used to say "tip" and now says "head", and the reason for the change is a small piece of practical drafting worth knowing. Javelin heads vary enormously in shape between manufacturers, which made a rule written around the tip hard to apply consistently. Judging against the head gives officials a larger and better defined area to assess. The principle underneath is unchanged: there has to be some angle on landing, however small, and flat or tail-first landings are still red-flagged.
So the question a judge is answering is not "did it stick" but "did it arrive nose down". At sixty, seventy, eighty metres, with the implement travelling fast and the officials looking along a shallow line of sight, that is a genuinely difficult call, and it is the reason two judges are stationed to watch the landing rather than one.
The landing surface is specified with the same problem in mind. It must be cinders, grass or other suitable material on which the implement makes an imprint. It must be even, and soft enough that the place of the initial fall can be clearly established. And it should not allow the implement to bounce backwards, because a bounce back over the mark obliterates the very thing the judges need to measure.
Read those requirements together and the design brief is obvious: the sector is not a lawn, it is a recording medium.
The redesign that made landings judgeable again
The specification tables in the current rules are not arbitrary numbers. They are the settlement of an argument the sport had with its own physics.
A javelin in flight has a centre of gravity, where its mass acts, and a centre of pressure, where the aerodynamic forces act. The relationship between the two determines how the implement pitches through its flight. Move the centre of gravity forward relative to the centre of pressure and the nose drops earlier, the implement stops gliding and comes down at an angle. Move it back and the javelin flattens out, holds height, and floats.
The floating version went further. It also landed flat, which meant more disputed calls, and it landed further from the arc, which meant an implement designed to be thrown in a stadium was arriving at the far end of one. The men's implement was redesigned in the 1980s to move the centre of gravity forward, and the women's implement was given the same treatment at the end of the following decade.
That is why the current rules constrain the centre of gravity so tightly. The specification does not simply give a weight and a length. It gives a permitted band for the distance from the tip of the metal head to the centre of gravity, and another for the distance from the tail to the centre of gravity, and it forbids any mobile part or other apparatus that could change the centre of gravity or the throwing characteristics during the throw.
Everything else the implement has to be
Weight is the specification everybody knows and the least of the constraints. The full list is long, it is checked before competition, and it disqualifies a great many objects that look like javelins.
| Implement | Women U18 | Women U20 and senior | Men U18 | Men U20 | Men senior |
|---|---|---|---|---|---|
| Javelin | 500g | 600g | 700g | 800g | 800g |
Those are minimum weights, inclusive of the cord grip. Beyond weight, the javelin must consist of three main parts: a shaft, a head and a cord grip.
| Specification | Men's 800g | Women's 600g |
|---|---|---|
| Length of metal head | 250mm to 330mm | 250mm to 330mm |
| Width of cord grip | 150mm to 160mm | 140mm to 150mm |
| Shaft diameter at thickest point | 25mm to 30mm | 20mm to 25mm |
| Tail to centre of gravity | 1540mm to 1800mm | 1280mm to 1500mm |
The head must be constructed completely of metal and terminate in a sharp point, with an angle of no more than 40 degrees at the tip. It may carry a reinforced tip of a different alloy provided the finished head is smooth and uniform along its whole surface.
The shaft may be solid or hollow, must be a fixed and integrated whole, and its surface must have no dimples, pimples, grooves, ridges, holes or roughness. The finish must be smooth and uniform throughout. Every one of those prohibited features is a way of managing airflow over a surface, which is precisely why they are prohibited: the rules will not have the sport turn into an aerodynamics competition between manufacturers.
The taper is specified in both directions from the grip. The maximum diameter must be immediately in front of the grip. At a point 0.15m from the tip, the diameter may not exceed 80 per cent of the maximum, and at the midpoint between the centre of gravity and the tip it may not exceed 90 per cent. Going the other way, the diameter at the midpoint between the centre of gravity and the tail may not be less than 90 per cent of the maximum, at 0.15m from the tail not less than 40 per cent, and at the very end of the tail not less than 3.5mm.
The longitudinal profile from the grip to each end must be straight or slightly convex, with no abrupt change in overall diameter except immediately behind the head and at the two ends of the grip. The reduction in diameter from immediately in front of the grip to immediately behind it may not exceed 0.25mm, and at the rear of the head the reduction may not exceed 2.5mm.
The cross-section must be regularly circular, with a permitted difference between the largest and smallest diameter at any cross-section of two per cent.
That profile requirement is checked with a metal straight edge at least 500mm long and two feeler gauges, one 0.20mm thick and one 1.25mm. Held against a straight section, it must be impossible to slide the 0.20mm gauge underneath anywhere along the contact. Against a slightly convex section, the straight edge rocks. Immediately behind the joint between head and shaft, the tolerance opens up to the 1.25mm gauge.
Somebody, in a room, checks a javelin with a ruler and two shims of metal. It is one of the least glamorous procedures in the sport and it is the reason the implement thrown in one country is the implement thrown in another.
The grip itself must cover the centre of gravity, must not exceed the average shaft diameter by more than 8mm, must be of uniform thickness, and may have a regular non-slip pattern but no thongs, notches or indentations of any kind.
And here is a small rule with a large implication that almost nothing written about the event mentions. Chalk on the implement is expressly permitted in the shot put and the discus. In the javelin it is expressly prohibited. Substances for grip are allowed on the hands, and taping of the hands and fingers is allowed, but the javelin itself must be thrown exactly as it was certified, with nothing added to its surface.
Implements are provided by the organisers. A technical delegate may allow athletes to use their own certified implements, checked and marked before the competition, but with a condition attached that changes the economics of the event entirely: they must be made available to all athletes. Bring your favourite javelin and everybody in the field may throw it. No athlete may submit more than two implements for an event, unless the technical delegate decides otherwise.
The runway, the arc, and the lines that end a throw
The runway is a straight strip marked by two parallel white lines 50mm wide and four metres apart.
The throw is made from behind an arc of a circle drawn with a radius of eight metres. The arc is a strip at least 70mm wide, painted or made from wood or a non-corrodible material such as plastic, white, and flush with the ground. Lines are drawn from the extremities of the arc at right angles to the parallel runway lines, white, at least 0.75m long and at least 70mm wide.
Those short right-angled lines are not decoration. They define, together with the arc, the boundary the athlete must be behind when they leave the runway, and a thrower who steps out in front of them has fouled a throw that has already landed legally.
The runway also has to be nearly flat, and in two different senses. Its maximum lateral inclination should be 1:100, which is one per cent, and over the last twenty metres the downward inclination in the direction of running must not exceed 1:1000, which is one tenth of one per cent. The landing sector is held to the same tenth of a per cent, measured from the level of the centre of the arc.
Those tolerances are far tighter than the equivalent for the high jump approach, and the reason is arithmetic. A javelin flies for several seconds and lands the better part of a hundred metres away. A slope that adds a fraction to the release height, or drops the landing area relative to the arc, is multiplied by that flight in a way it never is in an event that finishes two metres from where it started. The flatness rules for the jumps runways and the sprint straight exist for the same reason and are set at a different level because the geometry is different.
The fouls on the runway are precise about what part of the athlete matters.
It is a failure to touch, with any part of the body, the lines marking the runway, the throwing arc, or the ground outside. It is a failure to release the javelin other than as the rules permit. It is a failure to leave the runway before the implement has touched the ground. And when leaving, the athlete's first contact with the parallel lines or the ground outside must be completely behind the arc and its right-angled extension lines.
Then the exception that saves several throws a season. A touch made by a loose part of the shoe, such as a lace, or by clothing, or by any item that was attached to the athlete when the throw began and became detached during or after it, such as a cap, is not a failure. Unless the athlete overbalances, it is only the position of the feet that is critical. A hat falling across the arc has never invalidated anything.
The four-metre marks, which are not a foul line
There is one more mechanism on the runway, and it is routinely misdescribed as an extra restriction when it is the opposite.
A line, painted or theoretical and indicated by markers beside the runway, is drawn across the runway four metres back from the end points of the throwing arc. Once the implement has touched the ground, an athlete who makes contact with or is behind that line is considered to have left the runway correctly. If they are behind the line and still inside the runway at the moment the javelin lands, that also counts as leaving correctly.
The purpose is stated plainly in the rules: to speed up the judging process, not to create an additional way of calling a failure. It exists so the judges can raise the white flag and start measuring as soon as the thrower has retreated far enough back, rather than waiting for them to walk off the side of the runway. If a thrower never gets past the four-metre marks at all, the flag can go up as soon as the implement lands.
An athlete may also interrupt a trial once it has started, lay the implement down inside or outside the runway, and leave the runway, provided no other rule has already been broken. All of that has to happen inside the time allowed for the trial, which does not stop for a change of mind.
- The grip and the deliveryHeld at the grip with one hand, thrown over the shoulder or the upper arm. Not slung, not hurled, no unorthodox style.
- The body position through the run-upThe athlete may not turn completely around so that their back faces the arc at any point before the javelin leaves the hand.
- The feet, the arc and the runway linesAny contact by the body with the arc, the parallel lines or the ground beyond them is a failure. A loose lace, a cap or a piece of clothing making that contact is not.
- The flight, if anything is in the wayIt is a failure if any part of the javelin, after release and before it lands, touches an object outside the sector line.
- The landing attitudeThe metal head must strike the ground before any other part of the javelin. Some angle, however small, is required. Flat or tail-first is a red flag.
- Where the head first landsThe head must not touch the sector line or the ground outside it when it first contacts the ground. The lines are out, not in.
- Leaving the runwayThe athlete may not leave before the implement lands, and the first contact outside must be behind the arc and its extension lines, or behind the four-metre marks.
- The measurementFrom the nearest mark of the imprint, to the inside edge of the arc, along a line through the centre of the eight-metre circle. Rounded down to the centimetre.
Every step is a separate way to lose the throw, and they are assessed in this order because each one can only be judged once the previous one has happened.
Where 28.96 degrees comes from
The other three throws land in a sector of 34.92 degrees. The javelin lands in one of 28.96 degrees. Ask why and almost every source will tell you the javelin sector is narrower, which is true and explains nothing.
The javelin sector angle is not chosen. It is a consequence.
The rules define the sector lines geometrically rather than by angle. Their inner edges, if extended, must pass through the two points where the inner edges of the arc meet the parallel lines marking the runway, and must intersect at the centre of the circle that the arc is part of. Draw that and the angle is fixed by two numbers that were decided for other reasons: the arc has a radius of eight metres, and the runway is four metres wide.
The arithmetic follows in one line. The runway is four metres across, so each edge meets the arc two metres from the centre line. Two divided by eight is 0.25, which is the sine of half the sector angle. Half the angle is therefore a little under 14.5 degrees, and the sector is 28.96 degrees.
That is the whole derivation, and it explains something that otherwise looks like a historical accident. The javelin sector is narrower than the others because the javelin is thrown from a runway rather than a circle, and a runway has a width that the sector has to be built around. Change the runway to three metres or the arc to ten and the number changes with it.
The 34.92 degree sector used for the shot, discus and hammer is chosen rather than derived, and the rules give a builder's method for laying it out accurately: at twenty metres from the centre of the circle, the two sector lines are twelve metres apart, plus or minus five centimetres. For every metre out from the centre, the sector widens by 0.60m.
Landing rules follow the same logic in both cases. It is a failure if the head, in contacting the ground when it first lands, touches the sector line or the ground outside it. The line is out. And it is a failure if any part of the javelin, after release but before it lands, touches any object outside the sector line, which covers the implement clipping something on the way down.
Measurement, and the centimetre you always lose
Measurement in the javelin is done from a point that does not physically exist.
The distance runs from the nearest mark made by the head where it first contacts the ground, to the inside edge of the arc, along a line to the centre of the circle of which the arc is part. That centre is eight metres behind the arc, in the middle of the runway, and no throw is ever measured to it. It is a geometric reference that keeps every measurement radial, so that a throw landing at the left edge of the sector and one landing down the middle are measured on the same basis.
Unless video measurement is in use, a metal marker is placed vertically at the imprint nearest the arc, the zero end of a graduated steel tape is looped over it, and the tape is pulled out horizontally, with care taken not to lay it across a rise in the ground.
Then the recording rule, which is small, universal across the throws, and quietly consequential. Distances are recorded to the nearest 0.01m below the distance measured, if the measurement is not a whole centimetre. Always down. Never up, never to the nearest.
Every thrower in history has therefore lost a fraction of a centimetre on almost every throw of their career, and every result in the record books is a floor rather than a rounding. The rule exists so that no mark is ever credited with a distance that was not actually achieved, which is the correct principle and is worth stating plainly because the alternative would be a record book containing throws that never happened.
One more instruction covers something officials are occasionally tempted to skip. Every valid trial must be measured, whatever the distance reached. A short throw in round one is measured with the same care as a leader in round six, because measurements that look irrelevant become critical the moment a countback is needed or a place in the final rounds is being decided.
How a javelin competition is actually structured
The event's rules of engagement come from the general field event rule rather than the javelin rule, and they are the same for all four throws and the horizontal jumps.
The competing order is drawn by lot. If there has been a qualifying round, there is a fresh draw for the final.
Where there are more than eight athletes, everybody gets three trials and the eight with the best valid performances get three more. Where there are eight or fewer, everybody gets six. In both cases the order for the later rounds is reversed, so that after three rounds the athletes compete in reverse ranking order and the leader throws last.
Two refinements are worth knowing because they look like mistakes from the stand. Athletes who have not recorded a valid mark in the first three rounds compete before those who have, in their original draw order. And if there is a tie for the last place in the final three rounds, the tie is resolved on second-best performances; where it cannot be resolved, all the tying athletes get the extra trials. A field of nine in the closing rounds is the rules declining to invent a difference that the results do not contain.
That last principle runs right through to the podium, and it is where the throws differ most sharply from the vertical jumps. Ties in the throws are broken on the second-best performance, then the third-best, and so on down. If the athletes are still equal after all of that, it is a tie, and the tie stands for any place, including first.
There is no throw-off. Nothing corresponds to the jump-off that settles a tie at the top of a high jump, because in a throw the countback almost always separates people and, where it does not, the sport is content to say two athletes threw the same. The vertical jumps had to invent an extra competition precisely because a cleared bar is not a measurement.
A separate wrinkle applies at the one-day meetings that make up the season-long circuit, where throws at series meetings are run under a modified format that gives the leading three athletes a sixth round of their own, with the whole stadium's attention on it. That is a competition regulation layered on top of the technical rules, not a change to them, and the technical rules are what govern a championship.
Combined events are different again, in a way that catches people out. The javelin sits in both the decathlon and the heptathlon, where it is one scoring event among many and where the number of trials, the order and the way a mark converts into points are governed by the combined events scoring tables rather than by anything in the javelin rule.
The officials, and what they are each looking at
A properly staffed javelin event has a chief judge watching the whole competition, two judges checking that the throw has been made correctly and measuring the trial, and further officials on the runway and in the sector.
The division of labour is dictated by the geography. Nobody standing at the arc can judge a landing eighty metres away, and nobody standing in the sector can see whether a foot crossed a white line. So the calls are split, and the flag that goes up is the product of at least two people agreeing about two different things that happened at opposite ends of the field within about four seconds of each other.
One or more wind socks should be placed for the javelin and the discus, to show athletes the approximate direction and strength of the wind. Note what that is and is not. It is information, not regulation. The javelin has no wind limit and no wind-assisted category, unlike the sprints and the horizontal jumps, which is a point of genuine inconsistency in the sport and one that gets raised every time a strong headwind produces an unusually long series of throws. A headwind can help a javelin, by increasing the airflow over an implement designed to generate lift, which is exactly the situation the wind rules were written for in other events and are silent about in this one.
Officials are also told to take particular account of the availability of the runway when running or walking events are being held in the same area at the same time, which is the practical reason a javelin competition sometimes pauses for several minutes with a thrower standing at the top of the runway holding an implement.
And a rule so basic it reads as a joke until you consider the alternative: after each throw, implements are carried back to the area next to the runway, and never thrown back.
What to watch, and what the red flag usually means
Most red flags in a javelin competition come from three things, and once you know which is which the event becomes much easier to follow.
Watch the last two strides, not the release. Foot fouls at the arc are the commonest failure, and they are decided before the athlete's arm has done anything. A thrower who is running out of runway is going to foul, and it is visible a full second before the flag.
Watch the implement at the top of its flight. If the nose comes up and the javelin flattens, the landing will be flat and the throw will be dead regardless of distance. If the nose drops early, it is going in head first and the only question is where.
Watch the sector line at the landing, not the mark. The line is out. A javelin that lands nose down, cleanly, at ninety-five per cent of the athlete's best, and touches the line is worth nothing.
Watch the thrower after the throw. They must stay in the runway until the implement lands, and they must exit behind the arc or behind the four-metre marks. Throwers celebrating too early, or stepping forward to watch the flight, is not a rare sight.
Ignore the tape until the flag is white. No trial in which an irregularity has been committed should be measured under normal practice, so the appearance of a measuring official is itself the verdict.
The javelin is the only throw where the implement has to do something on arrival as well as travel a distance, and every rule described here is downstream of that one requirement. It is why the sector is a recording surface, why the implement's centre of gravity is fixed within millimetres, why chalk is banned on the shaft, and why an event that looks like pure strength is judged on an angle of a few degrees at the far end of a field. More on how the technical rules shape each discipline sits in the athletics archive, and the throws are where the rulebook is at its most physical.
Common questions
Does a javelin have to stick in the ground?
No, and this is the most persistent myth about the event. The rule requires only that the metal head strikes the ground before any other part of the javelin, so there has to be some angle on landing, however slight. The implement does not have to remain standing, or in the ground at all, and a throw that lands nose-first and falls flat is perfectly valid. Flat and tail-first landings are the ones that get a red flag.
How heavy is a javelin?
The senior men's implement is 800g and the senior women's is 600g, both minimum weights inclusive of the cord grip. Age groups use lighter implements: 700g for under-18 men, 500g for under-18 women, with under-20 women on the senior 600g and under-20 men on the senior 800g. Weight is only one of a dozen specifications a javelin has to meet before it can be certified.
Why is the javelin sector narrower than the other throws?
Because it is not chosen, it is derived. The other throws use a 34.92 degree sector; the javelin sector lines are drawn so that they pass through the two points where the inner edges of the 4m wide runway meet the 8m radius throwing arc, and converge at the centre of the circle that arc belongs to. Run the trigonometry on those two published numbers and 28.96 degrees is what falls out.
When is a javelin throw a foul?
If the athlete touches the arc, the runway lines or the ground beyond them with any part of the body; if they turn their back fully to the arc before releasing; if the throw is slung or hurled rather than delivered over the shoulder; if any part other than the metal head hits the ground first; if the head lands on or beyond the sector line; or if the athlete leaves the runway before the implement has landed, or leaves it in front of the arc.
Can you spin or turn around in a javelin run-up?
No. Until the javelin has been thrown, the athlete may not at any time turn completely around so that their back is towards the throwing arc, which rules out the rotational techniques used in the other throws. The restriction covers the run-up and the act of throwing only, so walking back before starting an attempt, or after interrupting one, is fine.
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