How heavy is a football?

Law 2 of the Laws of the Game, written by the International Football Association Board (IFAB), says the ball must be spherical, have a circumference of 68 to 70 cm (27 to 28 in) and weigh 410 to 450 g (14 to 16 oz) at the start of the match. Its pressure must be 0.6 to 1.1 atmospheres (600 to 1,100 g/cm²) at sea level. In official competitions the ball must also carry a FIFA Quality Programme mark.

The words “at the start of the match” matter. The rule does not cover what happens once play begins, when a ball can pick up water from wet grass or rain. That is why the weight is checked before kick-off, not during the game.

Manufacturers who want a FIFA mark send sample balls to a test institute. Each ball is inflated to 0.8 bar, kept for at least 24 hours at 20 °C and 65% humidity, then weighed on scales accurate to 0.01 g, out of the wind, five times. The average is its official weight.

The top grade, FIFA Quality Pro, demands 420 to 445 g and a circumference of 68.5 to 69.5 cm, tighter than the Laws themselves. The FIFA Quality grade uses the Laws’ own 410 to 450 g. In the water test the ball sits in 2 cm of water and is squashed 250 times; it must not gain more than 10% of its starting weight. A Pro ball may also lose no more than 20% of its pressure over 72 hours.

The ball was not always this heavy. The 1923 Laws of the Game set the weight for international matches at 13 to 15 ounces (about 370 to 425 g) at the start of play, with a leather outer case. The limit was raised to the current 14 to 16 oz in 1937, according to US Soccer’s referee answers.

The reputation of old balls as heavy comes from rain rather than the rules. Leather soaked up water during a wet match, which made the ball much heavier and painful to head. Modern synthetic covers barely absorb water, which is what FIFA’s 10% limit checks.