Kinetic Energy Calculator
Calculate kinetic energy using KE = ½mv². Enter mass and velocity to find energy in joules. Includes vehicle comparison table.
KINETIC ENERGY
450,000 J
IN kJ
450 kJ
IN ft⋅lbf
331,902.9 ft⋅lbf
FORMULA
KE = ½mv²
Kinetic Energy — Vehicle Examples
| Vehicle | Mass (kg) | Speed | KE |
|---|---|---|---|
| Bicycle | 90 | 6.7 m/s | 2.0201 kJ |
| Car (30 mph) | 1,500 | 13.4 m/s | 134.67 kJ |
| Car (60 mph) | 1,500 | 26.8 m/s | 538.68 kJ |
| Truck (60 mph) | 10,000 | 26.8 m/s | 3,591.2 kJ |
| Train | 100,000 | 44.7 m/s | 99,904.5 kJ |
💡 How to Calculate Kinetic Energy
What Is Kinetic Energy?
Kinetic energy is the energy an object has because it is moving. If something is in motion, it has kinetic energy. The amount of kinetic energy depends on how heavy the object is and how fast it is moving.
For instance, a speeding car has more kinetic energy than a rolling soccer ball because it is much heavier and moving faster. Kinetic energy is different from potential energy, which is the stored energy of an object based on its position. Objects that are not in motion have no kinetic energy at all.
How to Calculate Kinetic Energy
Since the amount of kinetic energy an object has depends on its mass and velocity, you need to calculate those things first. You can use our mass calculator and our velocity calculator to find those properties.
Once you have the mass and velocity, you can use a simple formula to calculate kinetic energy.
Kinetic Energy Formula
The formula to calculate the kinetic energy of an object is:
Thus, the kinetic energy KE in joules is equal to one-half times the object's mass m in kilograms times its velocity v in meters per second, squared.
Where:
- KE = kinetic energy (J)
- m = mass (kg)
- v = velocity (m/s)
Worked Example: Car at 60 mph
Let's calculate the kinetic energy of a 1,500 kg car traveling at 60 mph (26.8 m/s):
KE = ½ × 1,500 × 26.8²
KE = 750 × 718.24
KE = 538,680 J ≈ 539 kJ
At 30 mph: KE = ½ × 1,500 × 13.4² = 134,670 J ≈ 135 kJ. Doubling the speed quadruples the kinetic energy — and the stopping distance.
Why Speed Matters More Than Mass
Because KE depends on v² (velocity squared), speed has a much larger effect on kinetic energy than mass. A car at 60 mph has 4 times the kinetic energy of the same car at 30 mph — and needs 4 times the braking distance. This is why highway accidents are far more destructive than city crashes, and why speed limits exist.