Everyday Math
Speed Distance Time Calculator
Speed, Distance, and Time — The Core Formula
Speed, distance, and time are governed by one fundamental formula used in physics, navigation, athletics, and travel planning:
- Speed = Distance ÷ Time
- Distance = Speed × Time
- Time = Distance ÷ Speed
Enter any two values and this calculator instantly solves for the third.
How to Calculate Speed
Divide total distance by total time. This gives average speed over a journey, not instantaneous speed. Example: 240 km in 3 hours = 80 km/h.
How to Calculate Distance
Multiply speed by time (use consistent units). Example: 120 km/h × 2.5 hours = 300 km.
How to Calculate Travel Time
Divide distance by speed. Example: 450 miles ÷ 60 mph = 7.5 hours (7 h 30 min).
Speed Unit Conversions
| From | To km/h | To mph | To m/s |
|---|---|---|---|
| 1 mph | 1.60934 | — | 0.44704 |
| 1 km/h | — | 0.62137 | 0.27778 |
| 1 m/s | 3.6 | 2.23694 | — |
| 1 knot | 1.852 | 1.15078 | 0.51444 |
Real-World Speed References
- Walking pace: 5 km/h (3.1 mph)
- Cycling: 20–25 km/h (12–15 mph)
- Motorway: 100–130 km/h (62–81 mph)
- Commercial aircraft: 900–950 km/h (560–590 mph)
- Speed of sound: 1,235 km/h (767 mph)
- Usain Bolt peak speed: ~44.72 km/h (27.78 mph)
Frequently Asked Questions
How do I convert km/h to mph?
Multiply km/h by 0.62137. Example: 100 km/h = 62.1 mph.
How do I calculate running pace?
Pace (min/km) = 60 ÷ speed (km/h). At 10 km/h, pace = 6:00 min/km.
Related Tools
Unit Converter — convert all speed units instantly. Fuel Cost Calculator — estimate road trip fuel cost.
How to Use
- 1Choose what to calculateSelect whether you want to calculate Speed, Distance, or Time.
- 2Enter two known valuesFill in the two values you know, with their units. Leave the third field blank.
- 3Read your resultThe calculated value appears with the formula used, so you can verify the working.
Frequently Asked Questions
How do I calculate speed from distance and time?
Speed = Distance ÷ Time. Make sure units are consistent: if distance is in km and time is in hours, the result is km/h. For example, 120 km ÷ 1.5 hours = 80 km/h.
How do I convert km/h to mph?
Multiply km/h by 0.621371. For example, 100 km/h × 0.621371 = 62.14 mph. To convert mph to km/h, multiply by 1.60934.
How long does it take to travel 100 km at 80 km/h?
Time = Distance ÷ Speed = 100 ÷ 80 = 1.25 hours = 1 hour and 15 minutes.
What is the average walking speed in km/h?
Average walking speed is approximately 4–5 km/h (2.5–3 mph). At 5 km/h, you cover 1 km in 12 minutes and 5 km in 60 minutes.