Band Calculator
Speargun band calculator
Speargun Band Length Calculator (Looped Bands)
Use inches or cm (just be consistent).
End-to-end wishbone length (same units as D).
Extra rubber past each side of muzzle for tying.
Stretch ratio (e.g. 3.2 = 320%)
Rubber Cut Length (L):
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Formula: L = (2 × (D + I) + W) ÷ S
Band Length Table (by Gun Size)
This table uses your current W, I, and stretch selection, and applies them to common gun sizes.
Edit the bandTableRows list in the script to match your exact models.
| Gun Size | Slot-to-Fin (D) | Cut Rubber Length (L) |
|---|