Pace Calculator Guide
A pace calculator is three tools in one: it solves any of pace, time, and distance from the other two; it predicts what your fitness implies at other race distances; and it paces your race with a split table. This guide covers how to use each mode well — and where the predictions deserve skepticism.
The Three Solve Modes
| You know | You get | Typical use |
|---|---|---|
| Time + distance | Pace | "What pace did my 25:00 5K work out to?" → 5:00/km |
| Pace + distance | Finish time | "What does 5:30/km give me for a half?" → 1:56:02 |
| Time + pace | Distance | "How far do I get in 45:00 at 6:00/km?" → 7.5 km |
Our pace calculator always reports both unit systems — min/km with min/mile, km/h with mph — and full pace-to-finish-time tables live in the running pace chart.
Reading the Race Predictions
The predictions table uses the Riegel formula to scale your solved performance to 5K, 10K, half, and full marathon. The one-sentence honest reading: it tells you what your current fitness supports if you also train the distance. A 25:00 5K genuinely implies a ~52:07 10K — but only implies the ~3:59:47 marathon if the long-run volume exists. The formula's mechanics and limits are unpacked in the race time predictor guide.
Pacing With the Split Table
The cumulative split table at your goal pace is a race-day pacing sheet: at 5:30/km for a half marathon you should pass 5 km at 27:30 and 10 km at 55:00. Even pacing wins distance races — banking time early almost always costs more later than it saves. Pair pace zones with effort zones from the target heart rate calculator, and estimate the session's energy cost with the calories burned calculator.
Frequently Asked Questions
What is the difference between pace and speed?
Pace is time per distance (min/km or min/mile); speed is distance per time (km/h or mph). Runners plan in pace
because race targets are time-based; the two are reciprocals.
Should I race at an even pace?
For most distance races, yes — even or slightly negative splits (second half marginally faster) consistently
beat fast starts. The split table gives you the checkpoint times to hold that discipline.
What is a good 5K time?
Recreational runners commonly finish between 25 and 35 minutes; a sub-25 5K (under 5:00/km) is a solid amateur
benchmark, and sub-20 is competitive club level. Age and training history shift the bands.