IBO Speed Chart & Real-World Speed Calculator
Understand IBO speed ratings and convert them to real-world arrow speed for your actual setup. Includes reference chart by draw length and arrow weight.
🎯 IBO to Real Speed Calculator
Enter your bow's IBO rating and your actual setup to estimate real-world arrow speed.
Speed = IBO + (DW−70)×2 + 10×(DL−30) − (AW−350)/3 − string penalties
This is an approximation. Real speed depends on your specific bow's efficiency. Always verify with a chronograph.
📊 IBO Speed Chart by Bow Rating
Estimated real-world speed at common setups from various IBO ratings. Assumes 29 in draw, 80% let-off, and 10 gr string accessories.
| IBO Rating | @ 60 lb / 425 gr | @ 65 lb / 425 gr | @ 70 lb / 425 gr | @ 70 lb / 500 gr | @ 70 lb / 550 gr |
|---|---|---|---|---|---|
| 310 fps | ~277 | ~285 | ~292 | ~278 | ~265 |
| 320 fps | ~286 | ~294 | ~302 | ~288 | ~275 |
| 330 fps | ~296 | ~304 | ~312 | ~298 | ~285 |
| 340 fps | ~306 | ~314 | ~322 | ~308 | ~295 |
| 350 fps | ~316 | ~324 | ~332 | ~318 | ~305 |
| 360 fps | ~326 | ~334 | ~342 | ~328 | ~315 |
| 370 fps | ~336 | ~344 | ~352 | ~338 | ~325 |
📖 What Is IBO Speed?
IBO (International Bowhunting Organization) speed is the industry-standard benchmark for measuring a bow's speed under strictly controlled test conditions:
- Draw weight: 70 lb.
- Draw length: 30 inches.
- Arrow weight: 350 grains (5 grains per pound).
- String: No peep, no D-loop, no silencers.
- Measurement: Chronograph at the bow, not downrange.
These conditions are rare in real hunting. A shooter at 28 in draw and 65 lb with 425 grain hunting arrows will typically see 30–45 fps less than the printed IBO rating. That is normal and expected.
ATA vs IBO rating
The ATA (Archery Trade Association) uses an equivalent standard. Bow manufacturers list IBO or ATA ratings interchangeably. Both use the same test conditions.
⚖️ Variables That Reduce IBO Speed
| Variable | Effect on Real Speed |
|---|---|
| Each inch under 30 in draw | −10 to −12 fps |
| Each 1 lb under 70 lb draw weight | −1.5 to −2.5 fps |
| Each 25 gr over 350 gr arrow weight | −7 to −10 fps |
| Peep sight (10 gr) | −2 to −3 fps |
| D-loop (10 gr) | −2 to −3 fps |
| String silencers (set) | −2 to −4 fps |
| Drop-away rest (vs fixed) | ±0 fps |
| Heavier string (upgrade) | −3 to −6 fps |
| High let-off (85% vs 65%) | −3 to −6 fps |
These are approximate. Actual effects vary by bow design and cam system.
❓ Frequently Asked Questions
What is IBO speed?
IBO speed is a bow's speed rating measured under standardized conditions: 70 lb draw weight, 30 in draw length, 350 grain arrow (5 gr/lb), and no string accessories. It is set by the International Bowhunting Organization and is the industry reference point for comparing bows.
How do I convert IBO to real speed?
Real speed is typically 25–50 fps less than the IBO rating, depending on your draw weight, draw length, arrow weight, and string accessories. Use our IBO to real speed calculator above for your specific setup.
Is IBO speed the same as ATA speed?
Yes. ATA and IBO ratings use the same test conditions and are functionally interchangeable. Some manufacturers print one or the other; the value is the same.
Why is my real speed so much lower than the box?
Because the IBO test uses a 30 in draw, 70 lb draw weight, and a 350 grain bare arrow with no string accessories. Most hunters shoot shorter draw lengths, lighter poundage, heavier arrows, and add peeps and D-loops. Each of those factors reduces real speed by several fps.
Does a higher IBO rating mean a better bow?
Not necessarily. Higher IBO speed usually means harsher draw cycle, more hand shock, and louder shot. Bow design involves tradeoffs — speed, smoothness, quietness, and forgiveness. Fast bows are not automatically better for hunting.
What IBO rating do I need for deer hunting?
A bow with an IBO rating of 300 fps or higher can deliver 40+ ft-lb of KE with a 425 grain arrow at typical hunting setups. Most modern compound bows exceed 320 fps IBO, comfortably meeting ethical deer hunting energy requirements.
Can I trust manufacturer IBO numbers?
Yes — manufacturers publish honest numbers. But the numbers reflect test conditions that most hunters do not replicate. Focus on real chronograph speed with your own setup, not IBO rating.