How to measure for a Friendship Bracelet bag

How to measure for a bag. This is one bracelet, 16 strings, 24mm. 24/16=1.5 If you make it 12 bracelets wide that’s 12*16*1.5+(16*1.5) that will tell you how many mm the bag is. The bit in brackets is because each time you join two bracelets it adds a row. The measurements are based on the strings I’m using, make sure to check what you are using. This would give you circumference in mm.

It seems like no big deal, but a tiny amount time a lot is still a big difference.