Your 5 year old child weighs 3 stone is this average?

Answer 1

Primary use of the "stone" as unit of weight is in the British Isles.

One stone = 14 pounds; 3 stones = 42 pounds

I would cautiously say, yes, but IMO, Body Mass Index is more important. According to the BMI calculation for 42 pounds an average height of 3 feet 1 inch is indicated for a BMI score of 21.7

Different cultures and ethnicities mature and grow at different rates. What is considered normal or average for one group could be above or below another comparison group.

It is also to note the general health, activity level, motor skills, speech, etc., of your child - without reliance of a single factor.