Speed, Distance & Time Calculator
Pick the quantity you need, enter the other two, and get an instant result plus running/cycling pace.
Worked examples
Checking pace off a 5K finish time
A runner finishes a 5 km loop and wants to know both their average speed and their per-kilometer pace to compare against a training plan.
- Distance
- 5 km
- Time
- 25 min
≈ 12 km/h, pace 5:00 min/km
Distance covered on an interstate leg
A driver holds a steady 60 mph for two and a half hours on the interstate and wants to know how far that covered before checking the map for the next stop.
- Speed
- 60 mph
- Time
- 2 h 30 min
≈ 150 mi covered
How the formula works
Under constant speed, distance traveled is just speed multiplied by how long you travel — walk twice as fast, or twice as long, and you cover twice the distance. The same relationship rearranges to solve for either of the other two quantities: divide distance by time to find speed, or divide distance by speed to find how long the trip takes.
A classic memory aid is the "D over S T" triangle at right: cover up the quantity you want, and the remaining two letters tell you the operation — D on top with S and T below means covering D leaves S next to T (multiply), while covering S or T leaves one over the other (divide).
Frequently asked questions
How is running or cycling pace related to speed?
Pace is just speed turned upside down and rescaled to minutes: instead of "how far in one hour" it answers "how many minutes for one distance unit." Divide 60 by the speed in km/h to get minutes per kilometer, or 60 by the speed in mph to get minutes per mile — a faster speed always means a smaller (better) pace number.
Why does the calculator want time as hours, minutes, and seconds instead of one number?
Stopwatches, race splits, and trip logs are almost always read off in hours:minutes:seconds rather than a decimal, so entering "1 hr 15 min" directly avoids a mental conversion step and a likely rounding mistake. Flip the "decimal hours" switch if you already have a single decimal figure — the calculator keeps both representations in sync.
What exact conversion does this calculator use between miles and kilometers?
It uses the internationally-agreed exact value: 1 mile = 1.609344 kilometers, defined by the international yard-and-pound agreement and used as the basis for every mile/km figure in this calculator — nothing is rounded until the final displayed result.
What is a knot, and when would I use it instead of mph or km/h?
A knot is one nautical mile per hour (1 nautical mile = 1,852 meters exactly), the standard speed unit for marine and aviation navigation because nautical miles line up directly with minutes of latitude on a chart. Use it for boat, ship, or aircraft speeds; use mph or km/h for road and everyday travel.
Does this calculator account for acceleration or a changing speed?
No — it assumes constant speed for the whole distance and time you enter, the same way a simple "average speed" figure works for a full trip. If your speed varied, the result is the average speed that would have covered the same distance in the same total time, not the speed at any one instant.
Why did my computed time show something like "1h 15m 0s" instead of a decimal?
That's the calculator solving for time with the h:m:s format switched on — seconds are rounded to the nearest whole second (not cut off), and a rounded value of 60 seconds carries over into an extra minute automatically. Flip the "decimal hours" toggle if you'd rather see the same result as one number, like 1.25 h.