Calculate real-world arrow speed (FPS), kinetic energy (KE = m·v²/450240 in ft-lbs), momentum, and big-game hunting lethality with the free Arrow Speed Calculator.
208.0 mph • 93.0 m/s • Kinetic Energy: 86.8 ft-lbs • Momentum: 0.569 slug-ft/s
117.7 Joules
slug-ft/s (\(\text{lbf}\cdot\text{s}\))
Dangerous Big Game
334.7 km/h
grains per pound
93.1% speed retained
In archery ballistics, arrow speed (measured in feet per second, FPS) is the launch velocity of an arrow as it leaves the bow's arrow rest. While manufacturers publish factory IBO Speed Ratings (tested at a 70-lb draw weight, 30-inch draw length, and a 350-grain arrow with an unequipped bowstring), real-world hunting configurations differ significantly:
Personal draw lengths shorter than 30 inches, heavier hunting arrows, lower draw weights, and string accessories (peep sights, D-loops, brass nocks, string silencers) reduce real-world speed below the advertised IBO rating.
| Ballistic Metric | Formula | Description |
|---|---|---|
| Arrow Kinetic Energy (KE) | $$\text{KE} = \frac{m_{\text{grains}} \cdot v_{\text{fps}}^2}{450,240}$$ | Impact energy in foot-pounds (ft-lbs) |
| Arrow Momentum (\(p\)) | $$p = \frac{m_{\text{grains}} \cdot v_{\text{fps}}}{225,400}$$ | Penetration force in slug-ft/s (\(\text{lbf}\cdot\text{s}\)) |
| Draw Length Speed Correction | $$\Delta v_{\text{DL}} = (30 - \text{DL}) \times 10\text{ fps}$$ | 10 FPS lost per 1 inch below 30" |
| Arrow Weight Speed Correction | $$\Delta v_{\text{arrow}} = \frac{m_{\text{arrow}} - 5 \times \text{DW}}{3.5\text{ gr/fps}}$$ | 1 FPS lost per 3.5 grains added |
Input the manufacturer advertised IBO speed rating (typically 310 to 355 FPS).
Input your personal draw length in inches (e.g., 28.5") and bow draw weight in pounds (e.g., 65 lbs).
Input total arrow grain weight (shaft + insert + broadhead + fletchings + nock) and string accessories.
Inspect real-world launch velocity, foot-pounds of kinetic energy, momentum, game hunting category, and live KaTeX mathematical derivations.
Eliminates the disappointment of inflated factory IBO ratings by calculating true hunting setup arrow speeds before purchasing bows.
Ensures arrow setups deliver sufficient momentum and kinetic energy to achieve complete pass-throughs on elk, moose, and bear.
Provides accurate initial FPS inputs to generate precise multi-yard sight tapes for single-pin adjustable bow sights.
Accounts for draw length, draw weight, grains per pound (GPP), and string accessory weight deductions.
Calculates both kinetic energy (in ft-lbs & Joules) and linear momentum (in slug-ft/s).
Automatically benchmarks your arrow setup against small game, whitetail deer, elk, black bear, and dangerous game.
Why seasoned bowhunters favor heavy arrows over ultra-light speed setups:
While a light arrow shoots faster and yields a flatter trajectory at short yardages, a heavier arrow (\(450\text{ to }550+\text{ grains}\)) absorbs a significantly higher percentage of the bow's stored potential energy, resulting in a quieter shot with less bow hand vibration. Furthermore, in terminal ballistics, soft tissue and heavy bone penetration depth is directly proportional to momentum (\(p = m \cdot v\)) rather than kinetic energy. Heavy arrows retain momentum through bone impacts far better than light arrows that deflect or shatter on heavy ribs and shoulder blades.
How forward weight distribution stabilizes broadhead flight:
Front of Center (FOC) describes the percentage of an arrow's total weight concentrated in the front half of the arrow shaft:
Standard target archery setups use \(7\%\) to \(11\%\) FOC, while hunting setups with fixed-blade broadheads benefit from \(12\%\) to \(18\%\) FOC. High FOC acts like a badminton shuttlecock: it pulls the arrow forward through turbulence, minimizes wind drift, and prevents broadhead planing.
Why matching shaft stiffness to bow draw weight is critical for speed and accuracy:
When the bowstring is released, explosive acceleration compresses the arrow from the rear, causing the shaft to flex violently in flight (the Archer's Paradox). If an arrow is too weak in spine (e.g., shooting a .400 spine arrow from an 80-lb compound bow), excess oscillation robs energy, reduces effective launch speed, and causes erratic group sizes. A correctly spined arrow (.300 or .250 spine) dampens oscillations in less than \(0.05\text{ seconds}\), preserving maximum downrange speed.
Comprehensive answers to common questions about arrow speed calculations, IBO bow ratings, kinetic energy formulas, momentum, and game hunting thresholds.
