Calculate compound-bow holding weight, peak draw weight, or let-off percentage from the other two values.
Compound Bow Let-Off Formula
Let-off describes the percentage reduction from peak draw force to the minimum holding force near full draw under a defined measurement method.
How the Calculation Works
Holding weight equals peak draw weight multiplied by one minus the let-off fraction. The other modes rearrange that same relationship. Enter only the visible source values.
How to Use This Calculator
- Select the value or workflow you want in the Solve for menu.
- Enter only the visible source values and use the units shown beside them.
- Select Calculate and review the primary answer, supporting values, warning, and steps.
- Use Reset before starting a different bow, arrow, or round.
Worked Example
A 70 lbf peak draw weight with 80% let-off gives a calculated holding weight of 14.00 lbf: 70 x (1 – 0.80).
Input and Result Guide
| Item | How to use it |
|---|---|
| Peak draw weight | Use a measured or manufacturer-specified peak force in pounds-force. |
| Holding weight | Use the minimum force in the valley under the same test setup. |
| Let-off | Enter a percentage below 100 when solving for peak or holding weight. |
| Result | Compare only bows measured under the same method and draw-stop configuration. |
Interpreting the Result
Greater let-off means less force is held at full draw relative to the peak, but it does not by itself describe valley length, back wall, draw cycle, or shooting feel.
Assumptions and Limitations
Actual let-off depends on cam modules, cable stops, draw length, and the test procedure. This arithmetic does not generate a draw-force curve or verify a bow’s advertised specification.
Common Questions
Why did a field disappear after I changed Solve for?
A hidden field is either the requested output or irrelevant to the selected workflow. Enter the remaining visible source values.
Will my last successful calculation be restored?
Yes, when browser storage is available. It restores values and recomputes the result. Edits mark it stale until Calculate is selected again. Reset clears saved state.
Sources
Archery Trade Association, Technical Guidelines for compound-bow draw and let-down force measurements.
