Pace Calculator
Convert between pace, speed, and finish time for any distance
Your pace
Finish times at this pace
How to Use
- Pick a mode — Choose “Distance + time → pace” to find the pace of a run you already did, “Pace + distance → time” to predict a finish time at a steady pace, or “Target time → pace” to find the pace you need for a goal.
- Choose your unit — Toggle between kilometers and miles. The default follows your language, and all results update instantly when you switch.
- Enter your numbers — Type the distance and the time (hours / minutes / seconds) or the pace (minutes / seconds per unit), depending on the mode.
- Read the results — The headline shows your pace, speed, or finish time, and the table below shows what that pace means for the 5K, 10K, half marathon, and marathon.
Features
- Three calculation modes — Pace from a finished run, finish time from a planned pace, or required pace from a target time.
- Kilometers and miles — Per-locale defaults (miles for English, kilometers for Chinese and German) with a one-click toggle.
- Race prediction table — Instant finish times for the four standard race distances at your current pace.
- Exact conversion factor — Uses the international 1.609344 km-per-mile constant, so km and mile results always agree.
- 100% client-side — No data leaves your browser.
Use Cases
- Race planning: You want a sub-2:00 half marathon — enter 21.1 km and 1:59:59 to see the required pace (about 5:41/km).
- Workout analysis: You ran 10K in 50:00 — find your pace (5:00/km) and see what it predicts for the marathon.
- Treadmill conversion: Your treadmill shows km/h but your training plan is in min/km — convert between the two views instantly.
Related Tools
- BMI Calculator — another health tool for tracking body metrics.
- Sleep Calculator — plan recovery sleep around your training.
- Stopwatch & Timer — time your intervals and tempo runs.
Frequently Asked Questions
What is the difference between pace and speed?
Pace is the time it takes to cover one distance unit (e.g. 5:30 per kilometer), while speed is the distance covered per hour (e.g. 10.9 km/h). Runners usually train and race by pace because it maps directly to split times on a watch; speed is more common on treadmills and bikes. The calculator shows both.
How are the race finish-time predictions calculated?
The table multiplies your current pace by the official race distances (5K, 10K, half marathon at 21.0975 km, marathon at 42.195 km). It assumes you hold the same pace for the whole race — real-world finish times over longer distances are usually slower due to fatigue, so treat the marathon row as a best-case estimate.
How do I convert a per-mile pace to a per-kilometer pace?
One mile is exactly 1.609344 kilometers, so a per-mile pace divided by 1.609344 gives the equivalent per-kilometer pace. An 8:00/mi pace, for example, is about 4:58/km. Switching the unit toggle in the calculator does this conversion for you automatically.
Does the calculator store any of my data?
No. All calculations run entirely in your browser — no distances, times, or paces ever leave your device.