Five rulebooks, five projectiles, and no agreement on how exact a ball has to be

Every sport in this comparison has the same problem: name an object precisely enough that two of them behave alike, and loosely enough that somebody can manufacture it. Five governing bodies solved it, and the solutions are not variations on a theme. They are different in kind.

Mass, which is the one thing they all state

The numbers behind this chart

Row	Permitted range as a percentage of the smallest legal mass	Detail
Badminton — shuttlecock	16	4.74–5.5 g — Law 2.2
Football — football	10	410–450 g — Law 2.1
Volleyball — volleyball	8	260–280 g — Rule 3.1
Tennis — ball, type 2	6	56–59.4 g — Appendix I

Source Compiled from the five rulebooks named in the references, read 6 September 2026.
Method Each figure is (maximum − minimum) ÷ minimum for mass, as a percentage. Golf is excluded rather than plotted at zero: its rule states a maximum with no minimum, so the tolerance is undefined rather than nil.

The spread is not small. A shuttlecock may be nearly three times as loosely specified as a tennis ball, and the tightest and loosest specifications belong to the two lightest objects on the list.

Reference The shuttle’s mass range of 4.74 to 5.50 grams, from Law 2.2.6.

Reference The tennis ball’s mass range of 56.0 to 59.4 grams, from Appendix I.

That ordering rules out the obvious explanation. It is not that light objects are harder to make consistently, or that heavy ones are. Something else is deciding.

What decides it: whether the rule tests behaviour

Sort the same five rows by a different column — whether the rule applies a performance test as well as a dimensional one — and the pattern resolves.

Badminton, with the loosest dimensions by a distance, is the only sport that certifies its projectile by flying it: a shuttle struck with a full underhand stroke from the back boundary must land not less than 530 mm and not more than 990 mm short of the far line.

Reference The speed test — a full underhand stroke from over the back boundary line, landing 530 to 990 mm short of the other back boundary line — from Law 3.

Tennis, the tightest, also tests behaviour, but it tests it in a laboratory and it tests a great deal of it: a ball dropped from 254 cm onto a rigid block must rebound within a stated band, and its forward and return deformation are measured under an 80.07 N load after a 15.57 N contact load.

Reference The rebound test from 254 cm onto a rigid block and the deformation measurements under an 80.07 N load following a 15.57 N contact load, from the ITF’s test regulations.

Football and volleyball test neither. Their rules give dimensions and, in both cases, a pressure — and stop.

That is the finding, and it makes sense once stated. A rule that measures the outcome does not have to constrain the inputs tightly: two shuttles at opposite ends of a 16 per cent mass range are both correct if both land in the window. A rule with only dimensions has nothing else to lean on, so the dimensions have to carry the whole job.

Tennis is the apparent exception and is really the confirmation. It tests behaviour and specifies tightly, because it is not trying to certify one ball — it is trying to certify four different types that must each behave in a specific, different way, matched to a category of court pace. Precision there is not caution; it is the cost of running a system with several deliberately distinct products in it.

Pressure, where the disagreement is starkest

Only three of the five rules state an inflation pressure, and two of them are barely comparable.

A football must be of a pressure equal to 0.6 to 1.1 atmosphere at sea level — an upper limit 1.83 times the lower.

Reference The football’s permitted pressure of 0.6 to 1.1 atmosphere at sea level, from Law 2.1.

A volleyball’s inside pressure shall be 0.30 to 0.325 kg/cm² — an upper limit 1.083 times the lower.

Reference The volleyball’s inside pressure of 0.30 to 0.325 kg/cm², from Rule 3.1.

Eighty-three per cent against eight. Pressure is the property that most determines how a ball feels on contact — how far it deforms, how much of a strike comes back out of it — and one sport specifies it ten times more tightly than the other.

The reason is contact. A volleyball is struck with an open hand and passed off a forearm; a few per cent of hardness changes what a player can do with it. A football is struck with a boot, headed, and controlled with a chest and a thigh, and the range of contacts is so wide that no single pressure serves all of them. Football’s tolerance is not carelessness; it is an admission that there is no single right answer, and a decision to let competitions and manufacturers settle it inside a wide band.

The one that has no range

Golf is absent from the chart because its rule has no range to plot.

The weight of the ball must not be greater than 45.93 g. The diameter must not be less than 42.67 mm. There is no minimum mass and no maximum diameter.

Reference The golf ball’s maximum weight of 45.93 g and minimum diameter of 42.67 mm, from the Equipment Rules Part 4, sections 4.2 and 4.3.

Both bounds point against distance: more mass carries more momentum, and a smaller ball meets less drag. The unbounded directions are the ones that make the ball fly shorter, and nobody needs to be stopped from going there.

It is a specification with a completely different purpose from the other four. Football, volleyball, tennis and badminton are describing an object so that two of them are alike. Golf is drawing a line beyond which the ball goes too far.

What this comparison cannot show

Three limits, recorded in the compiled dataset rather than left to the chart.

Size is not comparable across rows. Football and volleyball state a circumference; tennis and golf a diameter; badminton the diameter of the circle the feather tips lie on. Those are four different measurements of four differently shaped objects, and converting between them would invent a comparison the rules do not support. Only mass compares directly, which is why mass is the only thing plotted.

A tolerance is what a rule permits, not what manufacturers do. Approved balls may cluster far inside the permitted band. Nothing here says how much real balls vary.

Several of these rules delegate. Law 2 requires balls in FIFA and confederation competitions to bear a mark of the FIFA Quality Programme, whose requirements are explicitly additional to the minimum specifications in the Law; golf’s initial-velocity and overall-distance limits are stated to exist and their values kept in a separate testing regime.

Reference That balls in official FIFA and confederation competitions must bear a mark of the FIFA Quality Programme, whose technical requirements are additional to the minimum specifications stipulated in Law 2, from Law 2.1.

So the figures above are floors, not the whole standard, in at least two of the five sports. What they compare is what each governing body chose to put in its own rulebook — and on that narrower question, the five could hardly be further apart.