Type any physics equation, drop in the constants, choose your units — and get the answer instantly. From Newton's gravity to photon energy, the universe resolves itself.
Not just arithmetic — a tool built around the way physical formulas actually work.
Enter an equation in plain text and watch it render in proper mathematical notation — fractions stacked, exponents raised, roots drawn.
Tap to insert G, c, ħ, ε₀, the mass of the Sun and dozens more. Every value pre-loaded in SI units.
Enter values in kilometres or miles, get answers in Joules, electronvolts or calories. Conversions happen automatically.
Clear, worked explanations of the formulas you'll use most — what each symbol means and how to compute it.
Why every mass pulls on every other, and how the inverse-square law sets the strength of that pull.
Read the guide →The energy of motion, where the factor of one-half comes from, and why speed matters more than mass.
Read the guide →How electric charges attract and repel — gravity's far stronger electrical cousin.
Read the guide →The most famous equation in physics, and what it really says about mass and energy.
Read the guide →Some of the greatest leaps in science began not in a laboratory but in the imagination. Explore the famous thought experiments that reshaped our understanding of reality.
Why you can't feel smooth motion from inside a cabin — the origin of the principle of relativity.
Read the guide →How a falling elevator revealed that gravity and acceleration are the same — and that gravity bends light.
Read the guide →The cat both alive and dead, and the quantum measurement puzzle it was designed to expose.
Read the guide →The accidents, rivalries and flashes of insight behind landmark discoveries — from an annoying hiss that turned out to be the echo of the Big Bang to two students who reinvented the electron.
How a stubborn hiss and a pair of pigeons led to the discovery of the Big Bang's afterglow.
Read the story →Two young students proposed it in an afternoon — then nearly withdrew the paper in panic.
Read the story →Chadwick chased a radiation others mistook for gamma rays — and unlocked the nucleus.
Read the story →No sign-up, no download. Open the calculator and start solving.