# Arrow Speed Calculator

Estimate arrow speed from IBO rating, draw length, draw weight, and arrow weight. Calculate kinetic energy and momentum for archery and bowhunting setups.

## What this calculates

Arrow speed depends on your bow's IBO rating adjusted for your actual setup. A 330 IBO bow shot at 28" draw, 60 lbs, with a 400-grain arrow produces roughly 260 fps, well below the rated 330. This calculator applies the standard industry adjustments so you can estimate your real-world arrow speed and the resulting kinetic energy and momentum.

## Inputs

- **IBO Speed Rating** (fps) — min 200, max 400 — Manufacturer's IBO speed rating (measured at 30" draw, 70 lbs, 350-grain arrow).
- **Draw Length** (in) — min 20, max 35 — Your actual draw length in inches (IBO standard is 30").
- **Draw Weight** (lbs) — min 20, max 100 — Actual draw weight in pounds (IBO standard is 70 lbs).
- **Total Arrow Weight** (gr) — min 200, max 1000 — Total arrow weight including broadhead, in grains (IBO standard is 350 gr).
- **String Accessories Weight** (gr) — min 0, max 100 — Weight of peep sight, D-loop, silencers, etc. in grains (typically 10-25 gr).

## Outputs

- **Estimated Arrow Speed** (fps) — Estimated arrow velocity in feet per second.
- **Kinetic Energy** (ft-lbs) — Arrow kinetic energy at launch.
- **Momentum** (slug-ft/s) — Arrow momentum (important for penetration).
- **Grains per Pound** (gr/lb) — Arrow weight ratio to draw weight (minimum 5 gr/lb recommended).

## Details

Bow manufacturers rate speed using the IBO standard: 30" draw length, 70 lbs draw weight, 350-grain arrow, and a bare bowstring. Your actual speed will differ based on these adjustments:

**Speed Adjustments from IBO:**
- **Draw length:** Subtract ~10 fps for each inch below 30" (add for each inch above)
- **Draw weight:** Subtract ~2 fps for each pound below 70 lbs (add for each pound above)
- **Arrow weight:** Subtract ~1 fps for each 5 grains above 350 (add for each 5 below)
- **String accessories:** Subtract ~1 fps for each 3 grains of peep, D-loop, silencers, etc.

**Hunting Kinetic Energy Guidelines:**
- **Small game (rabbits, turkeys):** 25+ ft-lbs
- **Medium game (whitetail, antelope):** 40+ ft-lbs
- **Large game (elk, moose):** 55+ ft-lbs
- **Dangerous game (grizzly, cape buffalo):** 65+ ft-lbs

Momentum matters more than raw energy for penetration. An arrow with high momentum punches through bone and hide more reliably. Most bowhunting experts recommend at least 0.40 slug-ft/s for whitetail and 0.50+ for elk.

The minimum safe arrow weight is 5 grains per pound of draw weight. Shooting lighter arrows risks damaging your bow (dry-fire effect) and produces excessive vibration.

## Frequently Asked Questions

**Q: What is IBO speed?**

A: IBO speed is the manufacturer-rated arrow velocity measured under standardized conditions set by the International Bowhunting Organization: 30-inch draw length, 70 pounds draw weight, 350-grain arrow, and a bare bowstring with no accessories. Most real-world setups shoot well below IBO speed.

**Q: What arrow speed do I need for hunting?**

A: For whitetail deer, most archers aim for 250-280 fps with a heavy enough arrow for adequate kinetic energy (40+ ft-lbs). Speed helps flatten trajectory and reduces the chance that game can 'jump the string,' but penetration (driven by momentum) is more important than raw speed.

**Q: Is kinetic energy or momentum more important?**

A: For penetration, momentum matters more. A heavy, slow arrow can penetrate better than a light, fast arrow with the same kinetic energy because momentum determines how well the arrow pushes through resistance. Many experienced bowhunters prioritize momentum over speed.

**Q: How accurate is this calculator?**

A: This gives a reasonable estimate, typically within 10-15 fps of actual chronograph readings. Real-world speed varies with cam timing, limb efficiency, bowstring material, arrow spine, and other factors. Always confirm with a chronograph for precise data.

---

Source: https://vastcalc.com/calculators/physics/arrow-speed
Category: Physics
Last updated: 2026-04-08