What is a stone?
A stone is 14 pounds, or about 6.35 kilograms, and the United Kingdom and Ireland use it almost entirely for body weight. Elsewhere people use kilograms or pounds.
We provide a calculator on this site to convert stones to kilograms.
What is an avoirdupois ounce?
An avoirdupois ounce is the ordinary ounce of the imperial and US customary systems, as opposed to the troy ounce used for gold and silver.
It is equal to 1/16 of a pound or approximately 28.35 grams. The avoirdupois system is based on a pound of 16 ounces, with larger units such as tons and pounds used for heavier measurements.