Pace Calculator
Running pace, finish time or distance, with splits and race predictions.
Pace, Time, Distance — Know Two, Get The Third
Enter a distance and a finish time to get your pace per kilometre and per mile, or a target pace to see your finish time, or a time and pace to see how far you would get. Pick a race — 5K, 10K, half marathon, marathon — and the distance fills in for you.
Alongside the answer you get your speed in km/h and mph, a split for every kilometre or mile at an even pace, and predicted times for every standard race distance using Peter Riegel’s formula, the most widely used race predictor among coaches.
Key features
- Solve for pace, time or distance.
- Kilometres or miles, with both paces shown.
- Race presets from 5K to the marathon.
- Even-pace splits for every kilometre or mile.
- Riegel race predictions for every standard distance.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: Pace Calculator
- Choose what to calculate
Pace, finish time or distance. - Pick a race or enter a distance
Switch units at any time; the distance converts with them. - Enter time or pace
Times as h:mm:ss, paces as mm:ss. - Use the splits
Glance at the split table on race day to stay even.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Calculators |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
What pace do I need for a sub-2-hour half marathon?
About 5:41 per kilometre or 9:09 per mile. Enter 21.0975 km and 1:59:59 with “Pace” selected to see it exactly, with every split.
How accurate are the race predictions?
Riegel’s formula, T₂ = T₁ × (D₂ ÷ D₁)^1.06, is reliable for trained runners between about 3 minutes and 4 hours. Predicting a marathon from a 5K usually comes out optimistic unless your training includes long runs.
What is the difference between pace and speed?
Pace is time per distance (minutes per km); speed is distance per time (km per hour). Runners usually think in pace, cyclists in speed. The calculator shows both.
Should I run even splits?
Even or slightly negative splits — running the second half a little faster — are how most records are set. Starting too fast costs more time later than it saves early.
Can I use it for cycling or walking?
Yes. The arithmetic is the same for any sport; only the predictions are specific to running.