Compound Bow Let-Off Calculator
Let-off is the percentage of peak draw weight your cams take off at full draw. Work out the holding weight you will actually be holding, or reverse it and find your bow's real let-off from a scale reading.
🎯 Compound Bow Let-Off Calculator
Enter your values below. Results update as you type.
Holding weight = Peak draw weight × (1 − Let-off ÷ 100)
Let-off % = (1 − Holding weight ÷ Peak draw weight) × 100
📊 Holding Weight by Let-Off
Holding weight at full draw for common peak draw weights and let-off settings.
| Peak Weight | 65% Let-Off | 75% Let-Off | 80% Let-Off | 85% Let-Off | 90% Let-Off |
|---|---|---|---|---|---|
| 50 lb | 17.5 lb | 12.5 lb | 10.0 lb | 7.5 lb | 5.0 lb |
| 60 lb | 21.0 lb | 15.0 lb | 12.0 lb | 9.0 lb | 6.0 lb |
| 65 lb | 22.8 lb | 16.3 lb | 13.0 lb | 9.8 lb | 6.5 lb |
| 70 lb | 24.5 lb | 17.5 lb | 14.0 lb | 10.5 lb | 7.0 lb |
| 80 lb | 28.0 lb | 20.0 lb | 16.0 lb | 12.0 lb | 8.0 lb |
⚙️ How to Measure Real Let-Off
- Hook a draw-weight scale to the string at the nocking point.
- Draw slowly through peak weight and note the highest reading.
- Continue to full draw until the cams hit the wall and the reading drops and settles. That settled value is the holding weight.
- Enter both numbers above using the "Let-off %" option.
Measured let-off is often a few points lower than the advertised figure. Draw length modules, limb bolt settings, and cam timing all change it.
Is more let-off always better?
No. High let-off makes it easier to hold for a long time, but a very light holding weight can feel unstable and make the bow easier to creep forward on. Many target archers prefer 65–75% for a firmer wall. Some hunting regulations also cap let-off, so check your local rules.
❓ Frequently Asked Questions
What is let-off on a compound bow?
Let-off is the percentage of peak draw weight removed by the cams at full draw. An 80% let-off bow set to 70 lb holds at 14 lb.
What is a good let-off percentage?
Most hunting compounds run 75–85%. Target archers often choose 65–75% for a more solid feel at full draw. There is no single best value; it depends on how long you hold and how you aim.
Does let-off change arrow speed?
Let-off itself does not directly set speed. Stored energy comes from the draw-force curve before the valley. Cams built for very high let-off can store slightly less energy, but cam design matters far more.
Why does my bow feel heavier than its let-off rating?
Advertised let-off is often measured under ideal conditions. Real let-off can be 2–5 points lower, so measure your holding weight with a scale to know for sure.
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Calculator results are planning estimates. Always confirm your setup with chronograph readings and real shooting.