Written by Muneeb Rana · Last updated 26 October 2026
Quick answer: This speed distance time calculator solves the classic triangle: speed equals distance divided by time, distance equals speed times time, and time equals distance divided by speed. Enter any two values, pick your units, and it fills in the third. For example, 150 miles at 60 mph takes 2 hours 30 minutes.
TL;DR
- Speed = distance ÷ time.
- Distance = speed × time.
- Time = distance ÷ speed.
- Mix units freely; the tool converts.
- Worked examples below.
Speed distance time calculator: the speed distance time formula
The relationship is the definition of average speed: how much distance is covered per unit of time. Write it as a triangle with D on top and S and T below; cover the value you want and the remaining two show the operation. The only trap is units: hours and minutes must be converted to decimal hours before dividing. Thirty minutes is 0.5 h, not 0.3.
Worked examples
- Speed: 90 km in 1 h 15 min → 90 ÷ 1.25 = 72 km/h.
- Distance: 45 mph for 40 min → 45 × 0.667 = 30 miles.
- Time: 200 miles at 65 mph → 200 ÷ 65 = 3.08 h ≈ 3 h 5 min.
- Walking: 5 km at 5 km/h → exactly 1 hour.
Average, not instant
The result is an average across the whole interval. A trip that averages 50 mph might include stretches at 70 and stops at 0. A live speedometer shows instant speed; a trip meter shows the average. See average speed vs max speed.
Handy decimal-time table
| Minutes | Decimal hours |
|---|---|
| 5 | 0.083 |
| 10 | 0.167 |
| 15 | 0.250 |
| 20 | 0.333 |
| 30 | 0.500 |
| 40 | 0.667 |
| 45 | 0.750 |
| 50 | 0.833 |
When to use which tool
Planning arrival times: travel time calculator. Checking a finished trip: average speed calculator. Running: pace calculator. Converting units: km/h to mph.
Units must match
Keep units consistent: miles with mph and hours, kilometres with km/h. Convert minutes to hours (divide by 60) before calculating.
Getting real numbers
Speedometer PRO's trip meter records distance and duration for you, and shows the average speed directly, so you can check your own commute without a stopwatch.
Related: Free speed tools · Average speed calculator · Travel time calculator · Running pace calculator · Average speed vs max speed · Trip meter: duration, distance, average and max speed · Online speedometer: your speed in the browser
Get Speedometer PRO on Google Play · Download on the App Store · Set it up before you move; never handle your phone while driving.
Sources
- Speed (Wikipedia): en.wikipedia.org (accessed 26 October 2026)
- Unit conversion (NIST Office of Weights and Measures): nist.gov (accessed 26 October 2026)
FAQ
What is the formula for speed?
Speed equals distance divided by time. For example, 120 km covered in 2 hours is an average of 60 km/h.
How do I calculate time from speed and distance?
Divide distance by speed, then turn the decimal part into minutes by multiplying it by 60. So 100 miles at 40 mph is 2.5 hours, or 2 hours 30 minutes.
How do I calculate distance?
Multiply speed by time in hours. Driving at 60 mph for 45 minutes, which is 0.75 h, covers 45 miles.
Can I mix miles and kilometres?
Yes. The calculator converts units for you, so you can enter distance in kilometres and get speed in mph.
Is the result instant speed?
No. It is an average over the whole time entered. Instant speed can be much higher or lower at any moment.