Enter mass and velocity, then click Calculate.
Kinetic Energy
The calculator uses the classical kinetic energy equation: KE = ½ · m · v²
- m is mass in kilograms (kg)
- v is velocity in meters per second (m/s)
- KE is energy in joules (J)
For unit outputs, joules are converted to foot‑pounds force using 1 J = 0.737562149 ft·lbf.
Momentum
Momentum is computed as p = m · v, reported as kg·m/s (equivalent to N·s). A convenient lbm·ft/s display is also provided.
- Choose the mass unit (grains, grams, kilograms, or pounds).
- Enter the projectile mass from your spec sheet.
- Choose the velocity unit (ft/s, m/s, km/h, or mph).
- Enter velocity (often muzzle speed), then click Calculate.
- Review energy and momentum in multiple units.
- Use CSV/PDF export to keep a record of results.
These are generic mass/speed pairs to demonstrate outputs.
| Preset | Mass (gr) | Velocity (ft/s) | Energy (J) | Energy (ft·lbf) | Momentum (N·s) |
|---|---|---|---|---|---|
| Example A | 55 | 3200 | 1,695.24 | 1,250.34 | 3.4761 |
| Example B | 90 | 1400 | 530.97 | 391.62 | 2.4886 |
| Example C | 124 | 1150 | 493.61 | 364.07 | 2.8165 |
| Example D | 147 | 1000 | 442.47 | 326.35 | 2.9034 |
| Example E | 158 | 1250 | 743.1 | 548.08 | 3.9008 |
| Example F | 180 | 1200 | 780.19 | 575.44 | 4.2662 |
| Example G | 200 | 1050 | 663.71 | 489.52 | 4.1476 |
| Example H | 230 | 950 | 624.8 | 460.83 | 4.3155 |
- CSV exports one row containing inputs, normalized units, and results.
- PDF exports a simple report view using a client-side generator.
- If PDF download is blocked, try allowing downloads for this site.
What the Calculator Measures
This tool estimates kinetic energy from projectile mass and speed, reporting joules, foot‑pounds force, and calories. It also computes momentum, letting you compare loads with similar energy but different mass or velocity.
Core Equation and Units
Energy is calculated with KE = 0.5 × m × v². Use kilograms and meters/second internally, then convert results. Because velocity is squared, a 10% speed increase raises energy by about 21%. Doubling velocity increases energy by four times.
Mass Conversions You Can Trust
Many specifications use grains. The calculator converts using 1 gr = 0.06479891 g and 1 lb = 0.45359237 kg. For example, 124 gr equals 8.035 g, or 0.008035 kg after conversion. Enter grams directly for scale measurements.
Velocity Conversions and Typical Inputs
Speed can be entered as ft/s, m/s, km/h, or mph. Conversions use 1 ft = 0.3048 m and 1 mph = 0.44704 m/s. If you switch from 1150 ft/s to 350.5 m/s, the computed energy stays consistent.
Energy Benchmarks in Joules and Foot‑Pounds
Unit output includes 1 J = 0.737562149 ft·lbf and 1 cal = 4.184 J. With example values, 124 gr at 1150 ft/s gives about 494 J (364 ft·lbf). A heavier 230 gr at 950 ft/s yields roughly 625 J (461 ft·lbf). A lighter 55 gr at 3200 ft/s produces about 1695 J (1250 ft·lbf) because speed dominates.
Momentum Adds Context
Momentum uses p = m × v and is shown as kg·m/s (N·s). For 124 gr at 1150 ft/s, momentum is about 2.82 N·s, while energy is 494 J. For 180 gr at 1200 ft/s, momentum rises to about 4.27 N·s and energy to 780 J. Momentum scales linearly with both inputs.
Exporting and Comparing Runs
After calculating, export a one‑row CSV for spreadsheets or a simple PDF report for sharing. Keep inputs, normalized units, and timestamps together. When comparing runs, change one variable at a time to see how mass scales linearly but velocity scales quadratically. This helps maintain consistent test notes.
1) Which units should I enter?
Enter mass in grains, grams, kilograms, or pounds, and velocity in ft/s, m/s, km/h, or mph. The calculator converts everything to kg and m/s internally for consistent results.
2) Why does speed affect energy so much?
Kinetic energy depends on v². That means doubling speed makes energy four times larger. Even small velocity changes can noticeably change joules and foot‑pounds.
3) Is the formula always accurate?
It’s the standard classical equation for kinetic energy. For extreme speeds approaching the speed of light, relativistic effects matter, and this estimate will understate true energy.
4) What is ft·lbf in this report?
ft·lbf is foot‑pounds force, a common energy unit. This tool converts using 1 joule = 0.737562149 ft·lbf, so both metric and imperial outputs match the same calculation.
5) Why does the calculator show momentum?
Momentum (m×v) helps compare “light and fast” versus “heavy and slower” cases. Two setups can have similar energy but different momentum, which changes how impulse and recoil feel in physics terms.
6) Can I export multiple rows at once?
The CSV export downloads one row per calculation. To build a multi‑row dataset, run several cases, download each CSV, then combine them in your spreadsheet app.