Free Physics Formula Lookup & Calculator

The Physics Formula Lookup & Calculator is a free online tool that search 80+ physics formulas by topic with variable definitions and solve-for-any-variable calculator. It runs entirely in your browser with no installation or sign-up needed.

Mechanics, waves, thermodynamics, electricity & magnetism, and optics — covering most high school and intro college physics.

Yes — for most formulas you can enter known values and solve for any unknown variable.

Yes, completely free.

Absolutely. The Physics Formula Lookup & Calculator processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the Physics Formula Lookup & Calculator is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the Physics Formula Lookup & Calculator in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The Physics Formula Lookup & Calculator works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

You don't have to rearrange the equation yourself. Open the calculator on a formula card, type in every value you already know, and leave the unknown field blank — the tool algebraically rearranges the formula and fills in the missing quantity. With Ohm's law (V = I·R), for example, enter current and resistance to get voltage, or enter voltage and resistance to get current. The same works for the ideal gas law, where you can leave pressure, volume, moles, or temperature empty and solve for whichever one is missing. This removes the most error-prone step in physics homework: transposing the equation by hand. Just remember to supply enough known values, since each formula needs all-but-one input to compute the remaining variable. Try it on any calculator-enabled formula card in the tool above.

No — common constants are filled in automatically whenever you leave their field blank, so you rarely need to look them up. The tool defaults gravitational acceleration g to 9.81 m/s², the gravitational constant G to 6.674 × 10⁻¹¹ N·m²/kg², the universal gas constant R to 8.314 J/(mol·K), the Coulomb constant k to 8.99 × 10⁹ N·m²/C², the speed of light c to 3 × 10⁸ m/s, and the Planck constant h to 6.626 × 10⁻³⁴ J·s. You can still override any of these by typing your own value if your course rounds g to 10 m/s² or uses a more precise figure. This makes formulas like weight (W = mg), Coulomb's law, and photon energy (E = hf) faster to compute. Enter only the quantities you measured and let the tool supply the rest.

Always use SI base units, because the solver works in consistent SI throughout and does not convert for you. That means metres for length (not centimetres), kilograms for mass (not grams), seconds for time, and newtons, joules, and watts for force, energy, and power. Temperature is especially important: the ideal gas law and Carnot efficiency formulas expect kelvin, not celsius, so add 273.15 before entering a temperature. Every variable on a formula card is labelled with its SI unit, which makes it easy to spot and fix a mismatch before you compute. Convert your inputs first — millimetres to metres, °C to K — and your results will be reliable. Seeing each quantity tagged with its unit also helps you catch unit-tracking mistakes that often sink physics problems. Check the variable list on any card above before entering numbers.

It automatically switches to scientific notation when an answer is very large or very small, so the number stays readable instead of running into a long string of zeros. Specifically, results with an absolute value below 0.001 or above 1,000,000 are shown in exponential form to four significant figures (for example 6.6260e-34), while values in the normal range appear as plain decimals. This is exactly what you need for physics, where quantities like photon energy, Coulomb forces, and the gravitational constant naturally span many orders of magnitude. Reading "1.6022e-19" as 1.6022 × 10⁻¹⁹ keeps tiny and huge results legible at a glance. The notation is only a display choice — the underlying calculation uses full precision. Solve any formula in the tool above and the answer formats itself appropriately.

Use the search box and topic pills at the top of the tool. Searching matches across formula names, the equations themselves, the topic, and individual variable symbols, so typing "voltage," "λ," or "momentum" jumps straight to the relevant cards as you type. If you'd rather browse, the topic filter pills — All, Mechanics, Waves, Thermodynamics, Electricity, and Optics — narrow the list to one area at a time, and a live count tells you how many formulas match. Each result card shows the equation, a plain-English description, and every variable with its symbol, meaning, and SI unit, so you can confirm you've found the right one before using it. There's also a copy button that copies the formula as text for your notes or lab report. Start typing a symbol or pick a topic pill above to filter instantly.