Speed CalculatorSpeed · Distance · Time
Speed equals distance divided by time (s = d ÷ t). This speed, distance and time calculator solves any one of the three from the other two. It converts between km/h, mph, m/s and knots, gives your running pace, and plots your result against everyday speeds, from walking to the speed of sound.
Formula verified against OpenStax — University Physics, Volume 1 · NIST Special Publication 811 — Guide for the Use of the SI
By Manzoor Ahmad · Pharmacist & calculator developerReviewed & updated
Speed · distance · time
Choose the unknown. Time can be entered in seconds, minutes or hours.
Step-by-step working
What is speed?
Speed is how fast an object moves: the distance it covers per unit of time. In SI units it is measured in metres per second, though km/h and mph are used for travel.
Speed is a scalar, so it ignores direction and depends on the total path length. Average speed covers a whole journey; instantaneous speed is what a speedometer reads at one moment.
Quick answers
How do I calculate my average speed for a trip?
Total distance divided by total time, including stops. 240 km covered in 3 h 20 min (3.333 h) averages 72 km/h. If you leave the stops out, you get your moving average instead, which is the figure most GPS units show.
How long will it take to drive a distance at a given speed?
Time = distance ÷ speed. 450 miles at 65 mph is 6.92 h, or 6 h 55 min of driving. Use the Find time tab; the answer is shown in hours, minutes and seconds.
How do I work out running pace from speed?
Pace in min/km = 60 ÷ speed in km/h. At 12 km/h you run 5:00 per km, which is a 25-minute 5K. The results panel lists pace per km and per mile for any speed.
What is the quickest way to convert km/h to m/s?
Divide by 3.6. 90 km/h ÷ 3.6 = 25 m/s. To go the other way, multiply by 3.6. For velocity problems with direction, use the velocity calculator.
Speed, distance and time formulas
The classic speed–distance–time triangle: cover the quantity you want, and the other two show you whether to multiply or divide.
| Symbol | Meaning | SI unit |
|---|---|---|
| s | Speed (average) | m/s |
| d | Distance travelled (total path length) | m |
| t | Time taken | s |
How to calculate speed
- Measure the total distance covered along the path.
- Measure the time, converting minutes to hours (÷ 60) if you want km/h or mph.
- Divide distance by time. 100 km in 1.25 h = 80 km/h.
- Convert if needed: km/h ÷ 1.609 = mph; m/s × 3.6 = km/h.
Worked example: a 100 km drive in 1 h 15 min
You drive 100 km and the trip takes 1 hour 15 minutes. What was your average speed?
s = 100 km ÷ 1.25 h = 80 km/h
80 km/h = 49.71 mph = 22.22 m/s
The answer is an average. You may have hit 110 km/h on the open road and crawled through a town, but the overall rate works out to 80 km/h.
Speed unit conversion table
Multiply by the factor to convert from the left-hand unit.
| From | To m/s | To km/h | To mph |
|---|---|---|---|
| 1 m/s | 1 | 3.6 | 2.23694 |
| 1 km/h | 0.27778 | 1 | 0.62137 |
| 1 mph | 0.44704 | 1.60934 | 1 |
| 1 knot | 0.51444 | 1.852 | 1.15078 |
| 1 ft/s | 0.3048 | 1.09728 | 0.68182 |
Running pace chart
Pace is the inverse of speed: time per unit distance. Runners usually think in minutes per km or per mile.
| Pace (min/km) | Speed (km/h) | Pace (min/mile) | 5 km time | Marathon time |
|---|---|---|---|---|
| 4:00 | 15.0 | 6:26 | 20:00 | 2:48:47 |
| 5:00 | 12.0 | 8:03 | 25:00 | 3:30:59 |
| 6:00 | 10.0 | 9:39 | 30:00 | 4:13:10 |
| 7:00 | 8.6 | 11:16 | 35:00 | 4:55:22 |
Common mistakes to avoid
- Adding minutes as decimals. 1 h 30 min is 1.5 h, not 1.30 h.
- Averaging two speeds directly. A round trip at 60 and 40 km/h averages 48 km/h, because more time is spent at 40.
- Mixing up speed and velocity. Speed uses total distance; velocity uses displacement and direction.
- Comparing pace and speed the wrong way round. A lower pace (min/km) means a faster runner.
Manzoor Ahmad
Pharmacist turned Web Developer & Calculator Engineer · 13+ years in web developmentI’m a pharmacist by training who turned into a full-time tech geek, and for 13+ years I’ve designed and coded web tools. My pharmacy degree included physical pharmacy and pharmaceutics — states of matter, heat, flow and reaction kinetics — so the physics behind these tools is familiar ground, not a new hobby.
I’m not a physicist, so I don’t ask you to take my word for it: every formula on this page is traced to an open university textbook or NIST reference data, and the calculator is tested against published worked examples before it goes live. Spot an error? Tell me and it will be fixed and dated on the next update.
Speed Calculator: frequently asked questions
Speed = distance ÷ time. Rearranged, distance = speed × time and time = distance ÷ speed.
Divide the total distance by the total time, including any stops. A 300 km trip that takes 4 hours in total averages 75 km/h.
Divide by 1.609344 (or multiply by 0.621371). For example, 100 km/h ≈ 62.14 mph.
Divide distance by speed: 300 km at 100 km/h takes 300 ÷ 100 = 3 hours.
Speed is distance per unit of time (km/h); pace is time per unit of distance (min/km). Pace = 60 ÷ speed in km/h.
Metres per second (m/s). Everyday alternatives are km/h, mph, knots (nautical miles per hour) and ft/s.
Speed is a scalar: it has magnitude only. Velocity is the matching vector quantity, which adds direction.
About 343 m/s (1,235 km/h, 767 mph) in dry air at 20 °C. It rises by roughly 0.6 m/s for every 1 °C increase in temperature.
References & sources
- OpenStax — University Physics, Volume 1 — Ch. 3, average speed and velocity
- NIST Special Publication 811 — Guide for the Use of the SI — conversion factors for mph, knot and ft/s
- HyperPhysics, Georgia State University — speed of sound in air
Disclaimer: This calculator is an educational tool built on idealised textbook models. It is not a substitute for professional engineering or safety calculations.