Run Pace Calculator

This calculator turns a distance and a finish time into your average pace and speed. Below is exactly how the math works, worked examples you can check by hand, and where a flat average pace stops telling the whole story.

How the Calculation Works

This tool converts the hours, minutes, and seconds you enter into a single total in seconds, then divides that total by the distance you entered to get seconds per unit — which it displays as minutes and seconds. Speed is calculated separately as distance divided by time in hours (total seconds ÷ 3,600), giving km/h or mph depending on which unit you selected.

One thing worth knowing: this calculator does not convert between kilometers and miles. The distance box and the km/miles dropdown are read together as-is — if you select "miles" and type 5, the result is your pace and speed for 5 miles, not a conversion of some other distance into miles. Always make sure the unit you pick matches the unit your distance is measured in.

Worked Example

Enter 10 km with a finish time of 50:00 (3,000 seconds):

• Pace: 3,000 ÷ 10 = 300 seconds per km = 5:00/km
• Speed: 10 ÷ (3,000 ÷ 3,600) = 10 ÷ 0.833 = 12.0 km/h

Switch to miles and the same math applies to a different number: 5 miles in 40:00 (2,400 seconds) gives a pace of 2,400 ÷ 5 = 480 seconds = 8:00/mile, and a speed of 5 ÷ (2,400 ÷ 3,600) = 7.5 mph. If a 5:00/km pace is around your goal, our average 10K time by age page shows how a pace like that compares to other runners' race results.

Using Your Pace

A single pace number becomes far more useful once it's part of a plan. Training plans typically prescribe several different paces — easy, tempo, and race pace — and this calculator is the quickest way to convert a target finish time into the number you'll watch on your wrist. Once you know your goal pace, our race split calculator turns it into a full checkpoint-by-checkpoint pacing chart for race day, and our race time predictor can estimate what that same fitness would produce at a different distance. For more on choosing paces for different workout types, see our guide to running pace strategy and what makes a tempo run different from an easy one.

Pace vs. Speed

Runners usually think in pace — minutes per kilometer or mile — because that's how race clocks, GPS watches, and split times are read. Speed (km/h or mph) is the same information turned around: speed = 3,600 ÷ pace in seconds. A 5:00/km pace (300 seconds) works out to 3,600 ÷ 300 = 12 km/h; a 6:00/km pace would be 10 km/h. Neither number is more "correct" — pace is generally easier to use for target splits, while speed is handy for treadmill dials, which are usually marked in km/h or mph rather than minutes per unit.

Limitations

This is an average-pace calculator, not a pacing-strategy tool — it divides your total distance into your total time evenly, so it can't tell you whether you actually ran even splits, negative splits, or faded badly in the final stretch. It also has no way to account for hills, wind, heat, or altitude, and it won't tell you whether a given pace is a comfortably aerobic effort or an all-out one for you personally; pairing a target pace with our heart rate zone calculator gives you an effort-based check alongside the raw number. And as noted above, remember that switching the unit dropdown doesn't convert your entered distance — it just changes which unit that same number is treated as.

Frequently Asked Questions

How do I calculate my running pace?

Divide your total time in seconds by your distance to get seconds per unit, then convert that into minutes and seconds — this calculator does exactly that: pace = total time ÷ distance, formatted as minutes:seconds per km or mile.

What is the difference between pace and speed?

Pace is time per unit of distance (minutes per km or mile) and speed is distance per unit of time (km/h or mph). They describe the same effort from opposite directions — speed in km/h equals 3,600 divided by your pace in seconds per km.

How do I convert a min/km pace to min/mile?

Multiply your pace in seconds per km by 1.60934 (the number of kilometers in a mile). A 5:00/km pace (300 seconds) becomes roughly 300 × 1.60934 = 483 seconds, or about 8:03 per mile.

What pace do I need to run a sub-4-hour marathon?

A marathon is 42.195 km, so a 4:00:00 (14,400 second) finish requires an average pace of 14,400 ÷ 42.195 ≈ 341 seconds per km, which is 5:41/km — or roughly 9:09 per mile.

How do I calculate my running speed in km/h or mph?

Divide your distance by your time expressed in hours. For a 10 km run in 50 minutes (0.833 hours), speed = 10 ÷ 0.833 = 12.0 km/h — the same calculation this tool runs automatically alongside your pace.

Does this calculator convert between miles and kilometers automatically?

No. The km/miles dropdown only labels the unit your entered distance is treated as — it doesn't convert one to the other. Make sure the number you type in the distance box actually matches the unit you've selected.

What pace should I run my long runs?

Long runs are typically run noticeably slower than your goal race pace, often at a conversational effort you could sustain while talking — this calculator can show you what a given "long run pace" looks like as a target once you decide how much slower than race pace you want to run.

Why does my GPS watch show a different pace than this calculator?

A GPS watch estimates your pace instant-by-instant from satellite positioning, which can drift under tree cover, in tunnels, or between tall buildings. This calculator instead computes your true average pace from the total distance and total time you enter, so the two numbers can differ even when your overall run was accurate.