Physics Formula Calculator
Pick a formula, choose which quantity to find, enter the rest in any unit — and get the rearranged formula, SI conversion and full substitution working.
Find a formula
Search by name, symbol or topic — e.g. “lens”, “KE”, “echo”.
First equation of motion
Step-by-step working
All formulas — quick reference
Tap any formula to open it in the calculator. Print it as a one-page revision sheet.
Solve numericals the exam way
Board examiners give marks for the formula, the substitution and the unit. This calculator writes all three for you so you can check your own working.
Pick a formula
Search or filter by topic — motion, force, energy, pressure, electricity, optics, waves or heat.
Choose the unknown
Tap any symbol under “Solve for”. The formula is rearranged for it automatically.
Enter values in any unit
km/h, grams, cm, minutes, kJ… Everything is converted to SI before substituting.
Read the working
See the rearranged formula, conversions, substitution and the final answer with its unit.
Always convert to SI first
Substitute only SI units: metre (m), kilogram (kg), second (s), ampere (A), kelvin (K).
- km/h → m/s: divide by 3.6 (72 km/h = 20 m/s)
- g → kg: divide by 1000 · cm → m: divide by 100
- 1 kWh = 1 unit = 3.6 × 10⁶ J
Rearranging a formula
Do the same operation on both sides until the unknown is alone. From v = u + at:
subtract u → v − u = at, divide by a → t = (v − u) ÷ a.
For squared quantities, take the square root at the end: v = √(u² + 2as).
Mirror and lens signs
Mirror: 1/f = 1/v + 1/u, m = −v/u. Lens: 1/f = 1/v − 1/u, m = v/u.
Negative m → real and inverted image. Positive m → virtual and erect. Lens power P = 1/f with f in metres (unit: dioptre, D).
Significant figures
Give the answer to about as many significant figures as the data — usually 3 or 4. Very large or small values are written in scientific notation, like 6.674 × 10⁻¹¹.