Running Pace Calculator — FAQ
Common questions about how the pace, time, and distance calculations work, what the split table shows, and how race finish-time predictions are made.
How does the pace calculator work?
Enter any two of pace, time, and distance and the tool instantly calculates the third — no button or page refresh needed. Leave pace blank to compute it from time and distance. Leave time blank to compute it from pace and distance. Leave distance blank to compute it from pace and time. Once the result is shown, a per-kilometre or per-mile split table and race finish-time predictions also appear automatically.
Is it free?
Completely free. No sign-up, no downloads, no limits — calculate as many times as you like on any device.
What can it calculate?
It solves any one of the three core running values from the other two:
— Pace from time + distance: useful after a run to find out how fast you ran each km or mile.
— Total time from pace + distance: useful before a race to predict your finish time from a target pace.
— Distance from pace + time: useful to see how far you covered in a given time at a set pace.
Does it show splits?
Yes. When both pace and distance are known — either entered or computed — a full split table appears below the results. It shows your cumulative time at every kilometre or mile, so you can see exactly where you will be at each segment of your run. For distances with a partial final unit (such as 42.195 km), the last row shows the time for that partial segment and the total finish time.
Can it predict race finish times?
Yes. Once pace is known — either entered or computed — the tool estimates your finish time for the 5K (5 km), 10K (10 km), half marathon (21.0975 km), and marathon (42.195 km). These predictions assume you hold your entered pace evenly throughout the race.
Does it support metric and imperial?
Yes. Use the km / mi toggle at the top of the calculator to switch units at any time. Existing pace and distance values convert automatically — so if you switch from km to mi, your 5:00 min/km pace becomes 8:03 min/mi and a 10 km distance becomes 6.214 miles. The split table and race predictions update to reflect the new unit too.
What is the difference between pace and speed?
Pace is time per distance unit: for example, 5:00 per km means it takes five minutes to cover each kilometre. Speed is distance per time unit: for example, 12 km/h means you cover 12 km in one hour. The two are inverses of each other. Runners and coaches typically use pace because it makes race planning straightforward — if your pace is 5:00 min/km and you are running a 10 km race, you know immediately that your finish time will be 50:00.
Are the race finish time predictions guaranteed?
No. The predictions assume you maintain your entered pace evenly for the entire race. Real race performance varies with course elevation, weather, pacing strategy, fatigue, and nutrition. Use the predictions as planning estimates rather than fixed targets, and adjust based on your own training experience and race conditions.
Is my data stored anywhere?
No. All calculations happen entirely in your browser. Your inputs are never stored, sent to a server, or shared with any third party.
Does it work on mobile?
Yes. The calculator is fully responsive at all screen sizes. Inputs, the unit toggle, distance presets, the results panel, and the split table all work on phones and tablets without horizontal overflow. The split table scrolls horizontally if needed on very narrow screens.
This tool provides general information and is not medical advice. Exercise intensity should match your own fitness and health. Please consult a physician before starting a new exercise routine or training at high intensity—especially if you have any heart condition, injury, or health concern.