Kinetic Energy Calculator
Calculate kinetic energy from mass and velocity, mass from energy and velocity, or velocity from energy and mass (KE = ½mv²), with unit pickers for J, kJ, MJ, cal, kcal, Wh, kWh, eV, BTU, ft·lb, and common mass and velocity units.
Input
Any two of energy, mass and velocity determine the third.
Output
| Quantity | Value | Other units |
|---|---|---|
| No data yet | ||
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/kinetic-energy-calculator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"solveFor": "energy",
"energy": "9",
"energyUnit": "j",
"mass": "2",
"massUnit": "kg",
"velocity": "3",
"velocityUnit": "ms"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `kinetic-energy-calculator` tool (Kinetic Energy Calculator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
Embed widget
<iframe
src="https://iotools.cloud/embed/kinetic-energy-calculator/"
width="100%" height="520" frameborder="0" scrolling="no" loading="lazy"
title="Kinetic Energy Calculator — iotools.cloud"
sandbox="allow-scripts allow-forms allow-same-origin allow-downloads allow-popups allow-popups-to-escape-sandbox"
allow="clipboard-write"
style="width:100%;border:1px solid #e5e7eb;border-radius:12px;overflow:hidden"></iframe>
<script src="https://iotools.cloud/embed.js" async></script>Drop this into your own page — free, no key required, just a link back.
| Cost per API/MCP call | From 5 credits |
|---|---|
| Need more credits? | View pricing |
Also available with
Guides
The Kinetic Energy Calculator solves KE = ½mv² — kinetic energy, mass, or velocity — pick the quantity you're missing, supply the other two, and it converts between J, kJ, MJ, cal, kcal, Wh, kWh, eV, BTU, ft·lb, and the common mass and velocity units along the way.
The formula
E = ½ × m × v²where E is kinetic energy, m is mass, and v is velocity. Rearranged for the other two quantities:
m = 2 × E ÷ v²
v = √(2 × E ÷ m)How to use it
- Pick what you want to Solve For — Kinetic Energy, Mass, or Velocity.
- Fill in the other two fields, each with its own unit picker: J, kJ, MJ, cal, kcal, Wh, kWh, eV, BTU, and ft·lb for energy; kg, g, mg, lb, oz, metric tons, and US (short) tons for mass; m/s, km/h, mph, ft/s, and knots for velocity.
- The result shows the solved value in every supported unit at once, so you don't need to run the calculator again just to see the same figure in kcal instead of joules.
Example
A 2 kg object moving at 3 m/s:
E = ½ × m × v² = ½ × 2 kg × (3 m/s)² = 9 JWhy does kinetic energy grow with the square of velocity?
Doubling an object's speed quadruples its kinetic energy, not just doubles it — that's why braking distance and crash severity rise so sharply with speed. A car going 60 mph carries four times the kinetic energy of the same car at 30 mph, not twice.
What's the difference between kinetic and potential energy?
Kinetic energy is the energy of motion (½mv²); potential energy is stored energy from position or state (like gravity or a stretched spring). A falling object trades potential energy for kinetic energy as it speeds up.
Privacy
All calculations run entirely in your browser. Your figures are never uploaded or stored.