Speed, distance and time calculator
Fill in any two of speed, distance and time and this calculator finds the third using the formula triangle. It shows which rearrangement it used, converts between m/s and km/h, and turns decimal hours into hours and minutes — the step that costs most marks in exam answers.
Fill in two boxes — leave the one you want blank
Distance is always in kilometres. Choose the units for speed and time below.
2 h 30 min
Speed: 60 km/h = 16.6667 m/s
Distance: 150 km = 150000 m
Time: 2.5 hours = 150 minutes (2 h 30 min)
Working
- Rearranged: time = distance ÷ speed
- 150 ÷ 60 km/h = 2.5 h
- In your chosen units: 2.5 hours, speed 60 km/h
The method behind it
- Speed = distance ÷ time; distance = speed × time; time = distance ÷ speed.
- Keep units consistent: km with hours for km/h, metres with seconds for m/s.
- km/h to m/s: divide by 3.6. Decimal hours to minutes: multiply the decimal part by 60.
How to use this tool
1. Leave the unknown blank
Enter the two quantities you know and leave the one you are finding empty. Units must be consistent with the ones you select.
2. Choose your units
Pick km/h or m/s for speed and hours or minutes for time. The calculator converts internally so the formula stays valid.
3. Read the rearrangement
The working shows the version of the formula used — speed = distance ÷ time, distance = speed × time, or time = distance ÷ speed.
Frequently asked questions
What is the formula for speed, distance and time?
Speed = distance ÷ time. Rearranged, distance = speed × time and time = distance ÷ speed. The formula triangle with D on top and S and T underneath gives all three.
How do you convert km/h to m/s?
Divide by 3.6. To go the other way, from m/s to km/h, multiply by 3.6. This comes from 1 km = 1000 m and 1 hour = 3600 seconds.
How do you convert a decimal answer in hours into minutes?
Multiply the decimal part by 60. So 2.25 hours is 2 hours and 0.25 × 60 = 15 minutes, written 2 hours 15 minutes — not 2 hours 25 minutes.
Does this work for average speed questions?
Yes, as long as you use total distance and total time. For a journey in stages, add the distances and add the times, then divide — you cannot average the individual speeds.
Practise this properly, not just once
A solver gives you the answer; exam marks come from the working. MathsGradeUp pairs exam-board questions with step-by-step feedback and revision notes on the exact topics you keep dropping marks on.