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Speed, distance & time
Solve for any one of the three — everything converts through SI units under the hood.
CALCULATOR · MATH · RATE
Speed Distance Time Calculator
Pick what to solve for, enter the other two, choose your units: 120 miles at 60 mph takes 2 hours — 2 hours 0 minutes, to be exact. Under the hood everything converts through SI units (meters, seconds), so mixing miles with km/h or feet with minutes just works. The marathon branch, the road-trip branch, and the metric branch below are all verified.
The 60-second rule
Speed = distance ÷ time. Distance = speed × time. Time = distance ÷ speed. One triangle, three readings. At the defaults — solve for time, 120 miles at 60 mph — time = 120 ÷ 60 = 2 hours (2 hours 0 minutes). Everything converts through meters and seconds first, so unit mixing is exact.
The worked example, line by line
Defaults: solve for time, 120 mi at 60 mph. Convert: 120 mi = 193,121.28 m; 60 mph = 26.8224 m/s. Time = 193,121.28 ÷ 26.8224 = 7,200 s = 2 hours — shown as 2 hours 0 minutes.
Branch — solve for speed (marathon): 26.2 miles in 4 hours. Speed = 26.2 ÷ 4 = 6.55 mph — the classic 4-hour marathon pace.
Branch — solve for distance (road trip): 70 mph for 45 minutes. Distance = 70 × 0.75 = 52.5 miles.
Branch — metric: 100 km at 100 km/h = 1 hour. And 62.1371 miles at 100 km/h also gives 1 hour — 62.1371 mi is exactly 100 km through the SI conversion.
Error branches: any input at or below 0 is rejected — a speed of 0 when solving for time or distance would mean dividing by zero, and negative distances are not a thing this calculator does.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Time | distance ÷ speed (via SI) | 2 hours at the defaults — 120 mi ÷ 60 mph. |
| Speed | distance ÷ time (via SI) | 6.55 mph for the 26.2-mi / 4-hr marathon branch. |
| Distance | speed × time (via SI) | 52.5 miles for the 70-mph / 45-min road-trip branch. |
| Friendly breakdown | hours, minutes, seconds of the answer | 2 hours 0 minutes — time answers always come with a readable breakdown. |
Who uses this
- The road-tripper: 70 mph for 45 minutes is 52.5 miles — arrival times without mental math, in whatever units the dashboard shows.
- The marathoner: 26.2 miles in 4 hours needs 6.55 mph — pace targets translated straight from the goal time.
- The student: physics homework with mixed units — miles against km/h, feet against minutes — solved exactly through SI.
- The metric traveler: 100 km at 100 km/h is 1 hour, and the same math works when the rental car’s odometer disagrees with the map.
Accuracy & limitations
Conversions are exact constants: 1 mile = 1,609.344 m, 1 ft = 0.3048 m, 1 mph = 0.44704 m/s. The formula itself is the definition of average speed — average being the operative word: it assumes constant speed and ignores stops, traffic, acceleration, and wind. Real trips take longer than distance ÷ speed; use the answer as the floor, not the plan.
Cite this calculatorBright Side Kit. “Speed Distance Time Calculator.” brightoolbox.com, 2026.
Bright Side Kit. "Speed Distance Time Calculator." https://brightoolbox.com/speed-distance-time/ Accessed October 23, 2026.Frequently asked questions
How do you calculate speed, distance, or time?
One triangle: speed = distance ÷ time, distance = speed × time, time = distance ÷ speed. This calculator solves whichever one you pick: 120 miles at 60 mph takes 2 hours; 26.2 miles in 4 hours needs 6.55 mph.
How do I convert mph to km/h?
Multiply by 1.609344: 60 mph = 96.56 km/h. To m/s, multiply mph by 0.44704 (60 mph = 26.82 m/s). The calculator does every conversion through SI units, so mixed units like miles with km/h stay exact.
What is 100 km/h in mph?
62.14 mph. Divide km/h by 1.609344. The calculator’s metric branch shows the reverse check: 100 km at 100 km/h takes exactly 1 hour.
How long does it take to drive 120 miles at 60 mph?
2 hours — 2 hours 0 minutes with the friendly breakdown. Real-world: that is the moving time only; add stops, traffic, and fuel for the actual arrival.
What pace do I need for a 4-hour marathon?
6.55 mph — 26.2 miles divided by 4 hours. That is about a 9:10 per-mile pace, and it assumes perfectly even splits with no walk breaks.
Why does it reject a speed of zero?
Because the math breaks: solving for time means dividing by speed, and dividing by zero is not defined. Standing still, the trip takes forever — which is technically true but not useful, so the calculator asks for a positive speed.