Arrow Weight Calculator (Total Grains & Grains per Pound)

How it works

Total weight (gr) = GPI × length (in) + point + insert + nock + vanes × vane weight + wrap · grams = grains × 0.0648 · GPP = total grains ÷ draw weight (lb) · 1 kg = 2.2046 lb, 1 in = 2.54 cm.

Arrow weight is quoted in grains (1 gr = 0.0648 g), and the shaft’s grains-per-inch (GPI) rating times its cut length gives the bare shaft weight. Adding the point, insert, nock, fletching and wrap gives the finished weight. Dividing by the bow’s draw weight in pounds gives grains per pound: the IBO speed-rating standard uses 5 GPP, and most bow makers forbid going lighter because too little arrow mass stresses the bow like a dry fire. About 6–8 GPP is a balanced all-round setup; heavier arrows are slower but carry more momentum.

Worked example

A 72 cm (28.3 in) shaft at 9.0 GPI weighs 255.1 gr. Adding a 100 gr point, 16 gr insert, 10 gr nock and 3 × 6 gr vanes gives a total of 399.1 gr (25.86 g). From a 27 kg (59.5 lb) bow that is 399.1 ÷ 59.5 = 6.71 GPP — a medium, all-round arrow.

Sources: Easton Archery — Shaft selector and specifications (GPI) · IBO — Arrow speed rating standard (5 grains per pound)

Frequently asked questions