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Pace Calculator

Pace, finish time or distance — enter any two and get the third, with race splits.

Enter any two of distance, time and pace to get the third.

Exact calculation. Given your inputs, this is the answer — no estimation involved.

How this calculator works

Three quantities, any two of which determine the third: time equals distance times pace. Pick what you want to solve for and enter the other two.

Everything is held internally in seconds and miles, then converted once for display, so switching between miles and kilometers never introduces drift.

Race distances use their official lengths rather than rounded approximations. A marathon is 42.195 km, which is 26.2188 miles — not 26.2. At a 7:00 pace that difference is about 8 seconds, which is small but real, and there is no reason to get it wrong.

The formula

Exactly what happens to your numbers, step by step.

The three relationships

time     = distance × pace
pace     = time ÷ distance
distance = time ÷ pace

Unit conversion
```
1 mile = 1,609.344 meters exactly
```
Defined exactly, so mile and kilometer paces convert without approximation.

A worked example

You ran 6 miles in 51 minutes. What was your pace, and what does it predict for a half marathon?

What you enter

Solving for: Pace
Distance: 6 miles
Time: 51:00

Step by step

Total seconds: 3,060
Seconds per mile: 3,060 ÷ 6 = 510
Pace: 8:30 per mile
Speed: 7.06 mph
Half marathon at this pace: 1:51:26

8:30 per mile — about 5:17 per kilometer

Race predictions from a single training run assume you can hold the pace for the full distance, which gets less true as the distance grows. Treat longer predictions as optimistic.

Assumptions

Every result here rests on these. Change your inputs and the result changes with them.

An even pace throughout. Real races involve terrain, fatigue and pacing decisions.
Race distances are the official ones: 5K is 5,000 m, a marathon 42,195 m.
Split times are cumulative elapsed time at each point.

What this cannot tell you

Race-time predictions from a shorter distance tend to be optimistic, because endurance does not scale linearly with speed.
Elevation, heat and wind are not modeled and all of them matter.

Questions people ask

How do I calculate running pace?

Divide your total time by the distance. 51 minutes over 6 miles is 8 minutes 30 seconds per mile.

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

About 9:09 per mile, or 5:41 per kilometer. Enter 26.2188 miles and 4 hours above to see it, along with every split along the way.

How do I convert between mile and kilometer pace?

Divide your mile pace by 1.609344 to get kilometer pace, or multiply the other way. An 8:00 mile is about 4:58 per kilometer.

Is a marathon exactly 26.2 miles?

Not quite. The official distance is 42.195 km, which is 26.2188 miles. The rounded 26.2 is close enough for conversation but this calculator uses the exact figure.

Sources and review

This calculator uses standard arithmetic with no external rules or published rates, so there is nothing to cite beyond the formulas shown above.

Methodology version 1.0.0 · Last reviewed September 20, 2026

Cite this calculator

For coursework, a resource list or your own site. How every calculator is built and checked is set out on the methodology page.

Citation

Chalk Calculator. (2026, September 20). Pace Calculator (Methodology version 1.0.0). https://chalkcalculator.com/pace-calculator/

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