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Physics Calculators

Free physics calculators that solve for any value, convert your units and show every step, from the formula to the answer.

Motion and forces

Kinematics Calculator

Any three of s, u, v, a and t give the other two, with the kinematic equation each step uses.

Velocity Calculator

Velocity from distance and time, or final velocity from an acceleration, in any units.

Acceleration Calculator

Acceleration from a change in velocity, or from a force and a mass.

Force Calculator

Newton's second law, F = ma, and weight, W = mg, solved for any value.

Gravitational Force Calculator

The pull between two masses, from Newton's law of gravitation.

Energy and momentum

Kinetic Energy Calculator

KE = ½mv², solved for the energy, the mass or the speed.

Potential Energy Calculator

Gravitational potential energy, mgh, and the energy stored in a spring.

Momentum Calculator

Momentum, p = mv, and the impulse of a force, J = FΔt.

Electricity

Ohm's Law Calculator

Any two of voltage, current, resistance and power give the other two.

Waves and light

Wavelength Calculator

Wavelength, frequency and wave speed, and the energy of a photon of light.

Matter and atoms

Density Calculator

Density, mass or volume from the other two, in kg/m³, g/cm³ or lb/ft³.

Half Life Calculator

The amount left after radioactive decay, the time it took, or the half life.

Physics calculators that show their working

Enter the values you know and each calculator here shows its working: the formula, the formula rearranged for the value you left blank, your units converted to SI, the numbers put in, and the answer. Those are the steps a physics teacher wants to see, so you can compare them with your own line by line.

You choose what to solve for by leaving it blank, so one page solves for different unknowns. A kinetic energy problem can ask for the energy, the mass or the speed; the kinematics page takes three of displacement, velocities, acceleration and time and finds the other two. When the values allow two answers, both are shown, and when they contradict each other, the page says which value does not fit.

How to use these while you are learning

  • Solve the problem on paper first, then compare your working with the steps here, line by line. The first line that differs is where to look.
  • Watch the unit conversion step. A speed in km/h or a mass in grams put straight into a formula is a common source of wrong answers.
  • Change one value and see which answers move. Doubling a speed quadruples a kinetic energy; doubling a mass only doubles it.
  • If no answer appears, check the units, the signs and the assumptions. A ball thrown up at 5 m/s with up as positive cannot reach 10 m, so no time fits that height.

What makes these different

  • Solve for any value. Leave blank what you want, fill in what you know.
  • Units are converted for you, km/h, mph, grams, pounds, milliamps and years included, and the conversion is shown as its own step.
  • Every step is on the page: the formula, the rearranged formula, the values put in, the answer.
  • No sign-up, no ads, and nothing you type leaves your browser.
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