1kg box = 160 pieces per box
160 pieces makes 30-32 bomboniere with 5 pieces in each
If you need to do 150 bomboniere you would do the following to work out how many kilos you need exactly.
150 (bomboniere) x 5 (pieces of confetti) = 750 (pieces total)
750 / 160 (the amount in each box) = 4.68 boxes
Round this off to the next whole number, which is 5.
You now know you will need 5 boxes to complete your bomboniere.