Built around rubber type, band diameter, band count and shaft mass — not shaft diameter alone.
Conventional circular bands
1. Gun & shaft
2. Rubber setup
3. Band construction
Factory-informed starting points include RIFFE technical setups, Rob Allen factory band/shaft pairings, Pathos TNT elongation guidance, and MAKO/Primeline published stretch recommendations. Use manufacturer-specific guidance when it is known.
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Speargun Band Length Calculator V.1
🌊 Band Builder
Speargun Band Calculator
Measure from the band slot to the shark fin, choose your setup,
and get a practical rubber cut length in seconds.
🐟
1
Enter your measurements
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in
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in
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in
Loading preference
Rubber stretch
Adjust this for your rubber and preferred loading effort.
300%
EasyBalancedPowerful
2
Your band length
Cut each rubber band to
28.25inches
Approximately 71.8 centimeters per band
Suggested preset
300%
Total rubber needed
84.75 in
Loaded rubber path
85 in
Stretch multiplier
3.00×
Formula used
((2 × slot-to-fin distance) − wishbone) ÷ stretch multiplier
+ allowance
💡
Shaft diameter does not directly change the geometry. It helps
choose a sensible starting stretch setting. Rubber diameter,
rubber formulation, shaft length, band count and gun stiffness
also affect the ideal setup.
Designed for conventional circular speargun bands. Roller and
inverted-roller guns require a different calculation.