Estimate compound-bow arrow speed from an advertised rating and setup differences, with a visible uncertainty range and chronograph-first warning.
Advertised Bow Speed Rule-of-Thumb
No official universal IBO or ATA correction formula converts a rating into real setup speed. This tool uses explicitly stated illustrative correction assumptions, not universally validated coefficients. Its reference setup is 30 inches, 70 lbf and a 350-grain arrow; verify the actual manufacturer rating setup before using it.
How the Calculation Works
The calculator applies the displayed formula or named lookup to the visible required inputs and reports one defined result.
How to Use This Calculator
- Verify that the advertised rating uses the reference setup stated in the calculator.
- Enter or select every visible required source value.
- Select Calculate and review the result, supporting values, warning, and steps.
- Use Reset before starting a different bow, arrow, or round.
Worked Example
A 340 fps rating, 28.5-inch draw, 65 lbf peak weight, 425-grain arrow, and 15 grains of string accessories gives a 285.0 fps rule-of-thumb center estimate.
Input and Result Guide
| Item | How to use it |
|---|---|
| Advertised rating | Use the bow maker’s published speed and verify which test convention it names. |
| Draw inputs | Use the measured draw length and peak draw weight for the setup. |
| Arrow weight | Use complete finished-arrow grains. |
| Accessory mass | Include added peep, loop, silencers, or other string mass when known. |
| Estimated range | The displayed ±10 fps band is illustrative, not validated accuracy or a prediction interval. Actual speed may fall outside it. |
| Actual speed | Measure the finished setup with a properly positioned chronograph. |
Interpreting the Result
The result is useful for a rough expectation or sensitivity comparison. A chronograph reading overrides it for energy, sight tape, and field decisions.
Assumptions and Limitations
The coefficients are not an official IBO or ATA rule and do not model cam design, efficiency, tune, string construction, release, or environmental conditions. Do not use this method for recurves or crossbows.
Common Questions
Are these universal speed corrections?
No. Cam design, arrow mass, and string accessory type and placement change these effects. Use the listed coefficients only as model assumptions; measure your configured bow with a chronograph.
Will my last successful calculation be restored?
Yes, when browser storage is available. It restores source values and recomputes the result. Edits mark it stale until Calculate is selected again. Reset clears saved state.
Sources
Mission Archery, speed-rating FAQ; Hoyt, 2026 Hunting Bow White Paper; International Bowhunting Organization, 2026 rules.