1kg box = 160 pieces per box
160 pieces makes 30-32 bomboniere with 5 pieces in each
If you need to do 100 bomboniere you would do the following to work out how many kilos you need exactly.
100 (bomboniere) x 5 (pieces of confetti) = 500 (pieces total)
500 / 160 (the amount in each box) = 3.125 boxes
Round this off to the next whole number, which is 4.
You now know you will need 4 boxes to complete your bomboniere.