Category · 8 tools
Free physics calculators for circuits, motion and energy
Physics problems are usually one formula away from an answer, but unit slips and algebra are where time and marks disappear. These calculators take the values you know — voltage, current, resistance, mass, distance, time — and return the rest with the formula printed next to the result, so you can see how the number was produced instead of trusting a black box.
Each tool is a focused browser calculator for a specific equation: Ohm's law and electrical power, speed and distance from time, acceleration, kinetic energy and density. Units are explicit and results are rounded for display only. They are study and quick-check tools, not a substitute for deriving the equation yourself or for safety-critical electrical work.
In this category
- Acceleration Calculator
- Density Calculator
- Kinetic Energy Calculator
- Ohm's Law Calculator
- Projectile Motion Calculator
- Resistor Color Code Calculator
- Speed Distance Time Calculator
- Wave Speed Calculator
Circuits, motion, forces and energy
Pick the equation, then check the units
Physics calculators are only as good as the values you feed them. Most wrong answers come from mixed units rather than bad algebra: centimetres entered into a metre field, grams instead of kilograms, or milliamps where amps are expected. Each calculator states the unit of every input and prints the equation under the result, so the quickest check is to re-derive the number by hand with the same units.
The electrical tools follow the standard relationships behind Ohm's law and power; the mechanics tools cover speed, acceleration, kinetic energy and density. Use them to check homework, compare scenarios or sanity-check a measurement, not to replace a derivation or a safety assessment. For real electrical work, isolation, fusing and local regulations matter more than any calculation.
- Checking two resistors in a circuit
- Enter voltage and resistance to get current, then use power to see how much heat the resistor must dissipate.
- Comparing a walk and a cycle ride
- Speed and distance from time makes the comparison explicit in consistent units instead of mixing minutes and hours.
- Sanity-checking a homework answer
- Reproduce the formula by hand with the values shown; if the units disagree, the calculator will too.
Guides for Physics Tools
All guidesThe format background, trade-offs and failure modes behind these tools — written for people who want to know why a conversion works the way it does.