The Arrow Performance Calculator is a free interactive tool from Altra Arrows that helps bowhunters and target archers visualize how arrow weight affects four critical performance metrics:

• Arrow speed (feet per second, fps)
•  Kinetic energy (foot-pounds, ft·lbs)
•  Momentum (slug·ft/s — the key penetration metric)
• Trajectory forgiveness (the ±3 yard impact miss window)

Unlike basic arrow speed calculators that only return a single number, this tool plots every arrow weight in your tuning window at once — so you can see the tradeoffs instantly and pick the build that matches your hunt.

Try it now: Arrow Performance Calculator

Pair it with: FOC Calculator to balance arrow weight with front-of-center for maximum penetration.

Step 1: Enter Your Bow Specs

In the left panel under Bow Specs, set three values:

Draw Weight (lbs): the peak weight you’re
pulling, measured on a digital scale.

IBO Speed (fps): your bow’s IBO rating from the manufacturer (the speed at 30″ draw, 70 lbs, 350-grain arrow). Look it up by bow model.

Draw Length (in): your actual draw length — every inch changes speed by about 10 fps.

Step 2: Enter Your Arrow Weight

Under My Build, type your total finished arrow weight in grains. This includes shaft + insert + point + nock + fletching. If you don’t know it, weigh a completed arrow on a grain scale at your local pro shop.

Step 3: Set Your Target Distance

Slide Target Distance to your typical shot distance. The ±3 yard miss band on the chart redraws to show how forgiving your build is at that range.

Step 4 (Optional): Lock to Your Chronograph

If you’ve shot your arrow over a chronograph, type the measured fps into the Chrono Speed field. The whole calculator recalibrates to your actual bow instead of relying on the IBO estimate. This is the most accurate mode.

The chart plots four lines and one shaded band across arrow weights from 350 to 900 grains. Lighter, faster arrows are on the left; heavier, slower arrows are on the right.

• Speed (white): Velocity in fps at each arrow weight -> Faster arrow, flatter trajectory
• KE (blue): Kinetic energy in ft·lbs -> More impact energy
• Momentum (yellow): Penetration potential -> Deeper penetration on game
• Time to Target (red dashed): Flight time to your target distance -> More gravity drop
• ±3 yd Miss Window (band): Vertical inches of error if you misjudge range by 3 yds -> Less forgiving build

Key takeaway: Speed drops as arrow weight rises, but kinetic energy increases until it plateaus — because heavier arrows extract more stored energy from the bow.

The chart background is divided into four color-coded zones based on Grains Per Pound (GPP) — total arrow weight divided by bow draw weight. The zones scale automatically with your draw weight.

Flat Trajectory (under ~6.5 GPP)

Lightest, fastest builds. Flat arc, shrinks the cost of misjudged yardage. Lower kinetic energy and momentum. Best for open-country hunting where shots stretch past 40 yards.

Optimal Balance (6.5–7.9 GPP)

The sweet spot most bowhunters land in. Forgiving trajectory plus meaningful KE and momentum gains. Versatile build for whitetails, mule deer, and elk-sized game.

Penetration Focus (7.9–9.3 GPP)

Momentum takes over. Trajectory drops more, speed bleeds, but the arrow drives deeper through bone and heavy muscle. Smart pick for elk, bear, and thick-skinned game.

Heavy Hitter (above 9.3 GPP)

Maximum momentum, dedicated heavy builds. Significant speed and trajectory penalty — best at close range on the biggest game.

The ±3 yard miss window shows how many vertical inches your arrow will hit off target if you misjudge the range to your target by 3 yards (high or low). This is the single most important number on the chart for ethical bowhunting.

Why 3 yards? Even with a rangefinder, real-world conditions — low light, animal movement, angle, terrain — push the typical ranging error to roughly ±3 yards. The faster your arrow, the less time gravity has to compound that mistake.

How to use it:

Narrow miss window = a forgiving build that
still hits where you aim if you misread the range.

Wide miss window = an unforgiving build that punishes range estimation errors.

The narrowest miss window that still delivers the energy you need for your game is your answer.

Three things happen as arrow
weight increases:

1. Speed decreases — heavier mass moves slower for the same energy input. Predicted by the virtual mass formula: v(m) = baseline × √(377 / (m + 27)).
2. Kinetic energy rises and plateaus — heavier arrows extract more stored energy from the bow (higher efficiency). KE never drops with arrow weight; it just gains slow down past about 500 gr.
3. Momentum rises linearly — momentum is mass × velocity, and the mass gain outpaces the velocity loss. Heavier arrows always carry more momentum.

This is why momentum is the better metric for penetration on big game — and KE is the better metric for energy on impact.

There’s no universal answer — it depends on your game and shot distances:

• Whitetail at 20–40 yards: 420–480 grains (Optimal Balance zone)
• Mule deer / elk at 30–60 yards: 460–520 grains (Optimal Balance zone)
• Elk / bear / moose at close to mid range: 500–600 grains (Penetration Focus zone)
• Tough game, close range: 600+ grains (Heavy Hitter zone)
• Target / 3D archery: 5–6 GPP (Flat Trajectory zone)

Use the calculator to test your specific build against your typical shot distance. The miss window will show you when speed loss becomes a problem.

For finer tuning, also check your Front of Center with our FOC Calculator. Higher FOC (typically 12–18% for hunting) improves penetration regardless of total arrow weight.

Five numbers update live as you change arrow weight:

• Arrow Speed — Real-world speed with a 2.5% efficiency adjustment baked in.
• Est. KE — Estimated kinetic energy in ft·lbs (3% real-world adjustment).
• Momentum — In slug·ft/s. Higher = better penetration on game.
• Time to Target — Seconds of flight to your target distance.
• ±3 Yard Miss Window — Vertical inches off your point of impact if you misread the range by 3 yards.

The speed model is fitted to chronograph data from four compound bows (Elite Artus, Elite Ethos, Mathews ARC30, Hoyt AX-3 33) across 16 data points spanning 354 to 748 grains. Root mean square error is 1.14 fps — within typical chronograph measurement noise.

That said, the calculator does not model:

• Broadhead drag (fixed-blade broadheads slow arrows slightly more than field points)
• Wind drift (heavier arrows resist wind better)
• FOC effects on penetration — use the FOC Calculator to dial that in.
• Arrow spine match — performance only matters with correctly spined arrows. Run the Spine Selector first.
• Archer form variability Treat the output as a highly accurate baseline, then fine-tune in the field.

Kinetic energy (KE) measures the energy delivered at impact — calculated as KE = (mass × velocity²) / 450,240. It scales with the square of velocity, so faster arrows benefit more.

Momentum measures penetration potential — calculated as mass × velocity. It scales linearly with both, so heavier arrows benefit more.

Rule of thumb: KE tells you how hard the arrow hits. Momentum tells you how deep it drives through. For hunting big game, prioritize momentum. For target work, KE is academic — focus on speed and trajectory

Use the calculator’s miss window to decide. Slide the arrow weight up and down at your typical shot distance:

• If the miss window stays under ~6 inches even at your heaviest weight, you have headroom to go heavy for more momentum.
• If the miss window balloons past 8 inches at moderate weights, you’re paying too much trajectory tax — go lighter.
• If you hunt multiple game types, build around your toughest target and accept the trajectory cost.

After choosing arrow weight, optimize penetration with front-of-center balance and pick a spine that matches your draw.

Use the chrono override. If you’ve measured your bow over a chronograph, type the fps into Chrono Speed. The whole chart locks to your real bow.

Compare two builds side by side. Note your current numbers, change arrow weight, compare. Easy way to choose between, for example, 450 gr and 500 gr.

Test your maximum shot distance. Push Target Distance to the longest ethical shot you’d take. If the miss window blows up, you’ve found your real range limit.

Pair with the FOC Calculator.
Total arrow weight is only half the penetration story. Use the Front of Center Calculator to balance the weight forward for maximum impact efficiency.

Export your results. “Export Data” produces a one-page PDF — your bow specs, build, results, chart, and full weight-sweep table. Useful for sharing with your pro shop or saving for tuning notes.

What does IBO speed mean?

IBO speed is the manufacturer-rated arrow velocity at 30-inch draw length, 70-pound draw weight, and a 350-grain arrow. It’s the industry-standard benchmark for comparing bow speed across models.

What is GPP (grains per pound)?

GPP is total arrow weight divided by bow draw weight. A 70-lb bow shooting a 490-grain arrow is at 7 GPP. The IBC and most manufacturers recommend a minimum of 5 GPP for safe bow operation. Below 5 GPP can damage your bow and void your warranty.

How does the calculator predict arrow speed?

It uses a virtual-mass speed model: v(m) = baseline × √(377 / (m + 27)), where baseline is adjusted from your IBO speed using IBO + (DL − 30) × 10 + (DW − 70) × 2. Validated against chronograph data with an RMSE of 1.14 fps.

Why does kinetic energy go up when speed goes down?

Heavier arrows extract more stored energy from the bow (bows are more efficient with heavier arrows). The energy gain from higher efficiency outweighs the speed loss, so KE rises with arrow weight — until efficiency gains plateau around 500 grains.

Is momentum or kinetic energy more important for hunting?

Momentum is the better predictor of penetration. KE tells you how hard an arrow hits; momentum tells you how deep it drives. For big or thick-skinned game (elk, bear, moose), prioritize momentum.

How is FOC different from arrow weight?

Arrow weight is the total mass of the finished arrow. Front of Center (FOC) is the location of the arrow’s balance point relative to its midpoint. Two arrows of the same total
weight can fly very differently depending on FOC. Use the FOC Calculator to optimize this.

What’s the minimum safe arrow weight for my bow?

5 grains per pound of draw weight is the universal floor. A 70-lb bow needs at least a 350-grain arrow. The calculator enforces this minimum automatically.

Can I use this calculator for crossbows?

The model is fitted to vertical compound bows. Crossbow ballistics differ enough that the speed predictions won’t be accurate.

Front of Center Calculator
Optimize your arrow’s balance point for maximum penetration. Use this alongside the Performance Calculator for a complete arrow build.

Spine Selector
Make sure your arrow spine matches your draw weight before tuning anything else.

Arrow Selector Quiz
Find the right Altra arrow for your bow and game.

Understanding GPI
Learn how shaft weight per inch shapes arrow flight.

Hunting Arrows · Target & 3D Arrows
Browse the Altra lineup.

The Arrow Performance Calculator enforces a 5 grains-per-pound minimum — the universal safety floor for compound bows. Never shoot an arrow lighter than 5 GPP of your draw weight. It can damage your bow, void your warranty, and cause serious injury. If you’re unsure of your finished arrow weight, ask your local archery dealer.