1 grain=64.8 milligrams.

1000 milligrams=1gram

A 350 grain arrow should weigh 22.68 grams

A 400 grain arrow should weigh 25.9 grams


Plenty of food scales and stuff like that are small enough to weigh grams...........you have to realize though that even precise Apothecary scales have a 5% margin of error so you can expect more then that from some cheap spring operated food scale. The % of error shouldn't be of much concern though as the mass you will be weighing is enough that it won't effect you unless it is WAY off.