How long is a ball of wool?

The number of metres in a ball of wool varies with the weight of the ball and the thickness of the yarn and the composition. Some balls of wool or yarn are 25 grams, some are 50 and others are 100 grams. A 50 gram ball of 8 ply (light worsted) pure wool will have around 100 metres but a 50 gram ball of a mixed 8 ply yarn (wool and acrylic) can have up to 200 metres. But then again a 50 gram ball of 12 ply wool (chunky) will only have around 50 metres.