What the Speed Distance Time Calculator does
This tool solves the classic relationship between how far you travel, how fast you go, and how long it takes. You give it any two of the three values and it works out the third for you. It is useful for drivers planning a journey, runners and cyclists checking their pace, students working through physics homework, and anyone who needs a quick average speed or estimated travel time without doing the arithmetic by hand. A simple example: covering 100 km at 50 km/h takes 2 hours.
How to use it
- Enter the Distance (km) if you know how far the trip is.
- Enter the Speed (km/h) if you know how fast you are moving.
- Enter the Time (hours) if you know how long it takes.
- Fill in exactly two of those fields and leave the third one blank.
- Press Calculate to see the missing value.
Worked example and a tip
Say you want your average speed over a 150 km drive that took 3 hours. Put 150 in Distance (km), put 3 in Time (hours), leave Speed (km/h) empty, then press Calculate to get 50 km/h. The one thing to watch is units: keep distance in kilometres and time in hours so the speed reads out cleanly in km/h. If your time is in minutes, divide by 60 first (45 minutes becomes 0.75 hours).
The calculator runs entirely in your browser, so the numbers you type stay private on your own device. It is completely free, needs no sign-up, and keeps working offline once the page has loaded.
Frequently asked questions
- How does the calculator know what to solve for?
- Fill in exactly two of the three fields and leave the one you want blank. The calculator detects the empty field and solves for it, so you do not pick a mode yourself.
- What formula does it use?
- It uses the standard relationships speed equals distance divided by time, time equals distance divided by speed, and distance equals speed multiplied by time. Keep your units in kilometres and hours for a clean answer.
- Can it work out average speed for a trip?
- Yes. Enter the total distance in km and the total time in hours, leave Speed blank, and the result is your average speed in km/h for the whole journey.
- Is my data sent to a server?
- No. The calculation runs entirely in your browser, so the numbers you enter never leave your device. It is free, needs no sign-up, and works offline once the page has loaded.
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Last updated: June 17, 2026