Arrow Speed Calculator
Work out what your bow actually shoots, not what the sticker on the riser claims. Enter your IBO rating, draw length, draw weight and arrow weight to get real speed, kinetic energy, momentum, and what the arrow is doing at 40 yards.
What an arrow speed calculator does
An arrow speed calculator estimates arrow velocity using bow speed, draw weight, draw length, and arrow weight. Arrow speed is measured in feet per second (fps). Heavier arrows generally travel slower, while lighter arrows travel faster. Actual speed also depends on bow efficiency, accessories, string weight, and shooting setup.
An IBO rating is measured under one fixed set of conditions: a 30 inch draw, 70 pounds of draw weight, and a 350 grain arrow with a bare string. Change any of those and the arrow leaves slower. This calculator applies the standard IBO adjustments to your own setup and tells you what to expect on a chronograph.
It also gives you the numbers that matter more than speed does: kinetic energy, momentum, grains per pound, and how much the arrow has slowed and dropped by the time it reaches the target.
How to use the arrow speed calculator
- Find your IBO rating: It is on the manufacturer's specification sheet for your bow model, usually quoted as a single number in fps or as a narrow range. Take the middle of a range rather than the top of it.
- Use your real draw length: Not the module setting you wish you had. This is the single largest correction in the whole calculation, worth about 10 fps an inch.
- Weigh the finished arrow: Shaft, insert, point, nock and fletching together, on a grain scale. Published shaft weights are per inch and exclude everything else, so guessing here is where most estimates go wrong.
- Count the string hardware: Peep, D-loop, nock set and silencers all add up. Under More options, enter the total in grains.
- Read past the headline: Speed is the least useful number on the page. Check kinetic energy against your intended use, and look at grains per pound to make sure the arrow is safe to shoot.
Arrow speed formula
An IBO rating is a laboratory figure produced under one fixed condition: 30 inches of draw, 70 pounds of draw weight, a 350 grain arrow, and nothing on the string. The industry-standard adjustments below convert that figure into something closer to what your own bow does.
v = IBO + (L - 30) x 10 - W/3 + min(0, -(A - 5D)/3)
KE = A x v² / 450,240
p = A x v / 225,218
GPP = A / D
Here v is arrow speed in fps, L is draw length in inches, D is peak draw weight in pounds, A is finished arrow weight in grains, and W is the added weight on the string in grains. Kinetic energy comes out in ft·lb and momentum in slug·ft/s; the constants simply carry grains and fps into those units.
Four rules are doing all the work. Each inch of draw length above or below 30 is worth about 10 fps. Every 3 grains of string hardware costs about 1 fps. Every 3 grains of arrow weight above the baseline of five times the draw weight costs about 1 fps. And there is no reward below that baseline, which is why the third term is capped at zero rather than allowed to run positive.
That cap is deliberate and it is the part people query most. A lighter-than-baseline arrow really does leave faster in the real world, but it does so by absorbing less of the bow's stored energy, which is exactly the condition manufacturers warn against. Rather than reward a setup that risks the limbs, the standard model stops crediting speed at five grains per pound.
Measurement standard reference: Archery Trade Association - ATA Technical Guidelines, the industry document defining how rating velocity, actual draw length and arrow measurements are taken.
Why heavier arrows lose speed but gain everything else
A bow stores a fixed amount of energy at full draw and hands most of it to the arrow. A lighter arrow takes that energy as velocity; a heavier one takes it as mass. Because kinetic energy scales with the square of speed but only linearly with mass, and momentum scales linearly with both, the three numbers do not move together. The table below runs a 330 IBO bow at 29 inches and 70 pounds through a range of arrow weights.
| Arrow weight | Grains per pound | Speed | Kinetic energy | Momentum |
|---|---|---|---|---|
| 350 grains | 5.0 | 316 fps | 77.6 ft·lb | 0.49 slug·ft/s |
| 400 grains | 5.7 | 299 fps | 79.4 ft·lb | 0.53 slug·ft/s |
| 450 grains | 6.4 | 283 fps | 80.0 ft·lb | 0.57 slug·ft/s |
| 500 grains | 7.1 | 266 fps | 78.6 ft·lb | 0.59 slug·ft/s |
| 600 grains | 8.6 | 233 fps | 72.3 ft·lb | 0.62 slug·ft/s |
| 700 grains | 10.0 | 200 fps | 62.1 ft·lb | 0.62 slug·ft/s |
Notice that speed falls steadily from top to bottom while kinetic energy barely moves across the middle of the table and momentum climbs the whole way. Between 400 and 500 grains this bow loses 33 fps and gives up less than a single foot-pound. That flat stretch is where most hunting arrows are built, and it is the reason the speed argument generates more heat than it deserves.
The figures are produced by the same model as the calculator, which caps the light-arrow bonus at five grains per pound. Real chronograph numbers below that line run faster than shown, which is precisely why bow manufacturers void warranties there.
Arrow selection reference: Easton Archery - Target & Hunting Arrow Selector, the spine and shaft charts used to match arrow weight to measured draw weight and draw length.
Worked examples
Four common setups run through the same adjustments, all with 12 grains of string hardware.
| Setup | Bow and draw | Arrow | Speed | Energy |
|---|---|---|---|---|
| Whitetail rig | 330 IBO, 29″, 70 lb | 425 gr | 291 fps | 79.9 ft·lb |
| Elk rig | 335 IBO, 29.5″, 72 lb | 500 gr | 280 fps | 87.0 ft·lb |
| Target and 3D | 320 IBO, 29″, 60 lb | 400 gr | 272 fps | 65.7 ft·lb |
| Short draw hunter | 330 IBO, 27″, 60 lb | 400 gr | 273 fps | 66.2 ft·lb |
The short draw hunter is the instructive one. Two inches of draw length cost 20 fps, and dropping from 70 to 60 pounds costs nothing at all in the IBO model because it lowers the arrow weight baseline at the same time. On a chronograph that setup would land several fps lower, which is what the field draw-weight option under More options is there to show.
Typical arrow speeds by bow type
Useful for sanity-checking a result. If the calculator hands you a number far outside the band for your bow type, an input is wrong, and it is usually the arrow weight.
| Bow type | Typical measured speed | Usual arrow | Notes |
|---|---|---|---|
| Modern hunting compound | 270 to 300 fps | 400 to 450 gr | Where most bowhunters actually land |
| Speed compound, light arrow | 300 to 340 fps | 350 to 400 gr | Loud, less forgiving of tuning errors |
| Target compound | 250 to 285 fps | 380 to 420 gr | Lower draw weight, stability preferred over speed |
| Olympic recurve | 180 to 210 fps | 300 to 350 gr | IBO ratings do not really apply |
| Traditional longbow | 150 to 185 fps | 450 to 600 gr | Heavy arrows, momentum over velocity |
| Crossbow | 330 to 450 fps | 380 to 450 gr bolt | Rated on power stroke, not draw length |
| Youth compound | 190 to 240 fps | 250 to 320 gr | Short draw dominates the result |
Recurves, longbows and crossbows are included for reference rather than accuracy. The IBO adjustment rules were written around compound bows, and applying a 30 inch baseline to a traditional bow or a power stroke measurement to a crossbow stretches the model past what it was built for.
How much kinetic energy do you actually need?
These are the widely used bowhunting guidelines, and the calculator checks your result against whichever one you pick. They are guidelines rather than physics: shot placement, broadhead design and arrow build decide outcomes far more than a threshold number does, and a well tuned arrow at the bottom of a band will outperform a poorly tuned one above it.
| Intended use | Kinetic energy | Typical arrow | What matters most |
|---|---|---|---|
| Target and 3D | No requirement | 350 to 420 gr | Consistency and forgiveness |
| Small game | Under 25 ft·lb | 300 to 400 gr | Point choice over energy |
| Deer sized game | 25 to 41 ft·lb | 400 to 450 gr | Sharp broadhead, clean pass-through |
| Elk and large game | 42 to 65 ft·lb | 450 to 550 gr | Momentum and structural arrow integrity |
| Big and heavy boned game | Above 65 ft·lb | 550 to 750 gr | Single bevel heads, high front of centre |
Most modern hunting setups clear the deer threshold with room to spare, which is why the interesting question is rarely whether you have enough energy. It is whether the arrow is built to hold together and keep driving after it hits something hard, and that is a momentum and construction question rather than a speed one.
Check your local hunting regulations before relying on any of this. Several jurisdictions set legally binding minimums for draw weight, arrow weight or broadhead cutting diameter, and those override any guideline table.
Example of a binding legal minimum: 58 Pa. Code § 141.43, which sets a 35 pound minimum peak draw weight and a 7/8 inch minimum broadhead width for archery deer season in Pennsylvania. Requirements differ in every jurisdiction, so check the rules where you hunt.
Gaining speed without buying a new bow
If the number came out lower than you hoped, there are only a few levers, and they are worth very different amounts. Work down them in order, and stop before the last one.
Fix the draw length first
An inch is worth about 10 fps, more than any other single change. But only lengthen it if the fit is genuinely short. A stretched draw wrecks form and costs more accuracy than the speed is worth.
Strip the string
A heavy peep, a bulky loop and a set of silencers can total 25 grains, which is around 8 fps for free. Lighter hardware is cheap and changes nothing else about how the bow shoots.
Then, carefully, the arrow
Every 3 grains removed is about 1 fps back, but this is the lever with a floor under it. Five grains per pound is the industry minimum, and going under it is close to dry-firing the bow.
One warning worth repeating: an underweight arrow leaves too much of the bow's stored energy in the limbs and cams. That energy has to go somewhere, and it goes into the bow. Manufacturers void warranties at that point for a reason.
Why your chronograph reads something different
Calculated speed and measured speed rarely match exactly, and the gap almost always traces back to one of the items below. The sizes are for a 330 IBO bow at 29 inches and 70 pounds shooting a 425 grain arrow, which this model puts at 291 fps.
| What you noticed | Likely cause | Size of the effect | Fix |
|---|---|---|---|
| Measured 10 to 15 fps slower | The IBO rating is a best-case marketing figure, often from a hand-picked bow | Commonly 5 to 15 fps | Treat the published rating as a ceiling and subtract before you start |
| Way off, in either direction | Arrow weight was estimated rather than weighed | 30 grains is 10 fps | Weigh a finished arrow on a grain scale, points and all |
| Slower than calculated by 5 to 10 fps | String hardware not counted, or heavier than assumed | 25 grains is about 8 fps | Weigh the peep, loop, nock set and silencers together |
| Draw length feels right but speed is low | Actual draw length is shorter than the module marking | Half an inch is 5 fps | Have it measured on a draw board rather than trusting the cam label |
| Dropped after a few hundred shots | String and cable creep, which shortens draw length and changes timing | 3 to 8 fps | Have the string measured and the bow re-timed at a shop |
| Slower in cold weather | Stiffer limbs and string material at low temperatures | Typically a few fps | Nothing to fix, but chronograph in the conditions you hunt in |
| Numbers scatter shot to shot | Chronograph light conditions, or arrows passing off-centre through the sensors | Several fps of noise | Shoot a group of five and average, in even indoor light |
| Faster than calculated | Arrow lighter than five grains per pound, where the model stops crediting speed | Can be 10 fps or more | Check grains per pound in the results and build a heavier arrow |
The pattern is worth noticing. Almost every discrepancy comes from an input being wrong rather than the formula being wrong, and two inputs cause most of it: the true draw length and the true finished arrow weight. Both are measurable in a few minutes, and neither is reliably guessable.
Interesting Fact
A grain is a genuinely ancient unit: one grain of barley, standardised at 1/7000 of a pound, or about 64.8 milligrams. Archery kept it when almost everything else moved on, and the reason is resolution. Three grains, roughly the weight of a grain of rice, is worth about 1 fps at the bow. A unit that lets you talk about a difference that small, on an object weighing less than an ounce, is exactly what arrow building needs, which is why grain scales still sit on every bow bench.
Frequently Asked Questions
What is an IBO speed rating, and how does it differ from AMO speed?
IBO speed is the velocity a bow produces under the International Bowhunting Organization's standard test conditions: 30 inches of draw, 70 pounds of draw weight, a 350 grain arrow and a bare string. AMO speed, the older standard still quoted on some equipment, uses a much heavier 540 grain arrow at 60 pounds, so an AMO figure always reads far lower for the same bow and the two cannot be compared side by side. Both exist so bows can be ranked against each other, not so you can predict what your own setup does. Almost nobody shoots those exact conditions, which is what this calculator corrects for.
How fast does an arrow actually travel?
A typical hunting compound bow with a realistic arrow lands between 270 and 300 fps, which is roughly 185 to 205 mph. Speed bows with light arrows reach the low 340s. A recurve bow runs around 180 to 210 fps and traditional longbows lower still, since far less of the archer's effort ends up stored in the limbs. Crossbows are the outlier, with many modern models above 400 fps. All of those are launch speeds measured at the bow; the velocity arriving at the target is always lower.
How much speed do I lose per inch of draw length?
About 10 fps for every inch under 30, and about 10 fps gained for every inch over. It is by far the largest correction in the calculation, which is why a 27 inch archer and a 30 inch archer shooting identical bows and arrows are 30 fps apart before anything else is considered. The reason is the power stroke: the distance over which the limbs are still pushing the arrow. Brace height works on the same quantity from the other end, so a bow with a short brace height has a longer power stroke and gains velocity, at the cost of being less forgiving of a sloppy release.
Why does more draw weight barely change the result?
Because in the IBO adjustment rules draw weight only appears inside the arrow weight baseline of five grains per pound. Raising draw weight raises the baseline, which reduces the arrow's weight penalty rather than adding speed directly. In the field, a rough figure of 2 fps per pound is closer to what chronographs show, and you can switch to that under More options. What you actually gain depends on the bow's efficiency and cam design, since an aggressive cam stores more energy per pound of draw weight than a smooth, forgiving one.
What is grains per pound and why does it matter?
It is finished arrow weight, meaning the shaft, insert, nock, fletching and broadhead or field point weighed together, divided by peak draw weight. It is the safety number in the whole calculation. Below five grains per pound the arrow cannot absorb enough of the bow's stored energy, and the excess is dumped into the limbs and cams instead. Most manufacturers treat anything under that line as a dry fire and void the warranty accordingly.
Is a faster arrow always better?
No. Speed buys a flatter trajectory, which forgives errors in range estimation, and that is a genuine advantage. It costs noise, more vibration, less forgiving tuning, and lower momentum. A fast arrow is also harder to tune with a large fixed blade broadhead, because the exposed blades steer the shaft in flight and drag exaggerates any tuning error already present. Between about 400 and 500 grains most bows give up a lot of speed for almost no kinetic energy, so the trade is far less one-sided than the marketing suggests.
How do I measure arrow speed without a chronograph?
There is a well known archery field method. Sight in at 20 yards, then shoot a group at 40 yards using the same 20 yard pin, and measure the vertical distance between the two group centres. The larger the gap, the slower the arrow, because it spent longer falling on the way there. It gives you an approximate launch speed rather than a real measurement, but it is a useful cross-check when no chronograph is available, and doubling the distance again makes the reading more sensitive.
How much speed does an arrow lose downrange?
Roughly 1.5 to 2 fps per yard for a typical hunting arrow, so a 290 fps arrow arrives at 40 yards somewhere near 260 fps. Drag is what takes it. Large fletching, a wide shaft diameter and an exposed broadhead all increase it, while micro diameter shafts and low profile vanes hold velocity noticeably better over distance. The downrange table in the results applies a representative decay rate rather than modelling your specific arrow, so treat it as indicative.
Does this work for recurves, longbows and crossbows?
Only loosely. The adjustment rules were built around the compound bow and its 30 inch baseline. A recurve bow has different draw length behaviour and a different efficiency curve, and a crossbow is rated on power stroke rather than draw length at all. You can still use the kinetic energy and momentum outputs if you enter a velocity you have measured yourself, since those depend only on arrow weight and speed, but the speed adjustment itself is designed for compounds.
How accurate are these estimates?
Expect to be within about 10 fps of a chronograph if your inputs are measured rather than guessed, and further off if the published IBO rating was optimistic or that individual bow's efficiency is below par for its model. The comparisons are much more reliable than the absolute number: the calculator is very good at telling you what 30 grains or half an inch of draw length is worth, and only approximate about the velocity you start from.
Other useful calculators
Water Cooling Calculator
Chilling times for a fridge, freezer, or ice bath.
Time Card Calculator
Total weekly hours, breaks, overtime, and gross pay.
Slack Time Calculator
Find float in a project schedule and spot the critical path.
Acceptance Rate Calculator
Work out acceptance rates from applications and offers.
Weighted Blanket Calculator
Match blanket weight to body weight and size.
Plant Population Calculator
Estimate plants per acre or hectare from row spacing.
Disclaimer: This arrow speed calculator provides planning estimates only. It applies the standard IBO adjustment rules to a manufacturer's published rating: 10 fps per inch of draw length, 1 fps per 3 grains of added string weight, and 1 fps per 3 grains of arrow weight above five grains per pound of draw weight, with no credit given below that baseline. Published IBO ratings are best-case laboratory figures and individual bows commonly measure below them.
The downrange table applies a representative velocity decay of roughly 1.5 fps per yard and calculates drop from a level launch under gravity alone. It does not model your specific arrow's drag, fletching, wind, or sight geometry, and it is not a substitute for sighting in and ranging on your own equipment.
Kinetic energy guidelines for hunting are widely used rules of thumb, not regulations or guarantees of outcome. Shot placement, broadhead sharpness and arrow construction matter more than any threshold figure. Check the hunting regulations in your jurisdiction, since minimum draw weights, arrow weights and broadhead requirements are set by law in many places and take precedence over anything here.
Never shoot an arrow lighter than the minimum specified by your bow's manufacturer, and have any bow re-checked by a technician after a dry fire or a suspected underweight shot.
Last updated: August 8, 2026