m = 80 kg, v = 10 m/s
KE = ½ × 80 × 10² = 4,000 J
Physics you can see and test
Kinetic Energy Formula Calculator
Solve for energy, mass, or speed across metric and US units, with transparent steps and a comparison showing why speed matters so much.
Free to use. No account required. Your inputs stay in this browser.
The essential relationship
KE = ½mv²
Kinetic energy is energy due to motion. It increases linearly with mass but with the square of speed, so doubling speed quadruples energy. The calculator keeps full precision internally and rounds only the displayed result.
Worked examples
Follow the numbers, one step at a time
m = 1,500 kg, v = 20 m/s
KE = 300,000 J
KE = 900 J, m = 50 kg
v = √(2KE/m) = 6 m/s
Built for understanding
More than an answer box
Every result includes the rearranged formula, substituted values, and a reasonableness check. Use the visual to connect the symbols to the measurement.
- Instant, private, browser-based calculation
- Decimal-friendly input and validation
- Responsive layout for phones and classrooms
- Copy-ready answer with units
Method and references
Formula basis
The formula follows standard textbook definitions. Unit symbols follow SI guidance; results are educational estimates, not engineering certification.
- OpenStax University Physics, Work and Kinetic Energy
- NIST SP 330, SI
Quick answers
Frequently asked questions
What is the kinetic energy formula?
KE = ½mv² for translational motion in classical mechanics.
What units should I use?
Kilograms and metres per second give energy in joules. The calculator converts common units.
Why is velocity squared?
The work needed to accelerate an object grows with the square of its speed.
When does this formula stop being accurate?
At speeds near light speed, relativistic kinetic energy is required.
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