Speed Calculator
Calculate speed, distance or time from the other two.
All calculations happen locally in your browser — nothing is uploaded, stored or tracked.
Pick what to find
Speed, distance or time.
Enter the two knowns
In any unit you like.
Read the answer
In all four speed units.
What Is a Speed Calculator?
Speed is distance divided by time — the classic formula from physics, also used in travel planning, traffic analysis and sports. This calculator solves for any one of the three quantities when you provide the other two.
Results are given in kilometres per hour, miles per hour, metres per second and knots, so the answer suits the context — driving, aviation or physics problems.
The Formulas
The calculator converts between all speed units using fixed factors: 1 km/h = 0.27778 m/s = 0.62137 mph = 0.53996 knots.
Your data never leaves your device.
Every calculation on this site runs in your browser using vanilla JavaScript. Nothing is uploaded, stored or tracked.
- 100% local, client-side calculations
- No data stored on any server
- No tracking, no analytics, no ads scripts
- Works offline once loaded
Frequently Asked Questions
How do I calculate speed?
Divide the distance by the time. 150 km in 2 hours is 75 km/h.
How do I convert km/h to mph?
Multiply by 0.62137: 100 km/h ≈ 62 mph.
How do I calculate travel time?
Divide distance by speed: 300 km at 100 km/h takes 3 hours.
What is the difference between speed and velocity?
Speed is a magnitude; velocity includes direction. This calculator works with speed.
Can I use it for marathon pace?
Yes — enter 42.195 km and your time to get your average speed; the pace calculator gives min/km.