Enter an object's mass and velocity to calculate its kinetic energy using the formula KE = ½mv². You can also solve for mass or velocity when the other two values are known. Choose your preferred units for mass (kg, g, lb), velocity (m/s, km/h, mph, ft/s), and energy output (J, kJ, MJ). Results include kinetic energy, an equivalent drop height, and a visual energy breakdown.
Kinetic Energy
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Kinetic Energy (kJ)
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Mass
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Velocity
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Equivalent Drop Height
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Kinetic energy is the energy an object possesses due to its motion. Any object with mass that is moving has kinetic energy — the faster it moves or the more massive it is, the greater its kinetic energy.
The standard formula is KE = ½mv², where KE is kinetic energy in Joules, m is the mass in kilograms, and v is the velocity in metres per second. Because velocity is squared, doubling speed quadruples the kinetic energy.
Rearranging KE = ½mv² gives v = √(2KE/m). Select 'Velocity (v)' as the solve-for mode, enter the known kinetic energy and mass, and the calculator returns the velocity automatically.
Rearranging the formula gives m = 2KE/v². Select 'Mass (m)' as the solve-for mode, provide the kinetic energy and velocity values, and the calculator computes the required mass.
You can enter mass in kg, g, lb, or oz; velocity in m/s, km/h, mph, ft/s, or cm/s; and view energy output in Joules, kilojoules, megajoules, watt-hours, or electronvolts. All unit conversions are handled automatically.
Equivalent drop height (h = KE / mg) is the height from which the object would need to be dropped to convert its potential energy into the same amount of kinetic energy. It gives an intuitive feel for how much energy is involved.
Because velocity is squared in the formula KE = ½mv², a small increase in speed produces a disproportionately large increase in kinetic energy. For example, doubling speed results in four times the kinetic energy, while tripling speed gives nine times the energy.
A 70 kg person running at 10 m/s has a kinetic energy of ½ × 70 × 10² = 3,500 J (3.5 kJ). A car weighing 1,500 kg travelling at 30 m/s has KE = ½ × 1500 × 900 = 675,000 J (675 kJ) — highlighting how much more energy is involved at highway speeds.