Speargun Band Stretch Factor Explained

Stretch factor is a ratio measurement, not a universal recommendation.

Relaxed length (L0)

Relaxed length is the rubber length between relevant connection points when the rubber is not stretched. Measure the exact same section later when stretched.

Stretched length (L1)

Stretched length is the length of that same rubber section in loaded or measured state. For a valid ratio, stretched length must be greater than relaxed length.

Stretch factor (R)

Stretch factor uses the formula R = L1 / L0. A value of 3.0× means stretched length is 300% of relaxed length. This explains the arithmetic convention only.

Manufacturer specifications

Different rubbers and setups may use different manufacturer specifications. Measuring a factor helps you compare your setup with those instructions. It does not mean the page is recommending a target factor.

Calculate measured ratio values with the Band Stretch Calculator.