Last updated: 2026-05-22

Three Numbers, One Equation

Distance, time, and pace form the simplest possible runner's equation. Know any two and the third is fixed — so this calculator is a three-way solver: pick what you want to find, enter the other two, and read off the answer. "Find Pace" turns a distance and a finish time into a pace; "Find Time" turns a distance and a target pace into a projected finish time; "Find Distance" turns a pace and a time into a distance covered. The reason it earns a dedicated calculator instead of a back-of-napkin division is unit handling — minutes-per-kilometre vs. minutes-per-mile vs. seconds-per-400 m — plus a per-split table and pacing references for race-distance milestones.

How It Works

The three quantities are linked by one relationship, written three ways:

$\text{pace} = \frac{\text{time}}{\text{distance}} \qquad \text{time} = \text{distance} \times \text{pace} \qquad \text{distance} = \frac{\text{time}}{\text{pace}}$

Each mode rearranges the same equation. Speed is reported alongside in every mode, and the "splits table" breaks the run into per-kilometreper-mile segments — useful for setting goal-pace alerts on a watch and for comparing actual splits to plan.

Pace, Speed, and Common Race Targets

Runners think in pace (lower is faster); cyclists, drivers, and most physics problems think in speed (higher is faster). They are reciprocals scaled by units:

*Asterisks mark paces that are at or beyond the elite world-record range.

Practical Scenarios

1. Goal-Pace Workouts

You target a 1:45 half marathon. Pace = 105 minutes / 21.0975 km ≈ 4:58/km.Pace = 105 minutes / 13.1 miles ≈ 8:00/mile. Now you know what to hold during tempo runs and what each kilometermile split should read on the watch.

2. Reading a Race Photo

You see a photo of a runner crossing a 10K finish in 50:00 elapsed time. Pace = 5:00/km.Pace ≈ 8:03/mile. That's the point of comparison for your own training — a benchmark to chase or accept.

3. Workout-to-Race Translation

Tempo runs are typically 10–20 seconds per km15–30 seconds per mile slower than 10K race pace; long-run pace is 60–90 seconds per km90–150 seconds per mile slower than marathon goal pace. Plug in your race-pace target and apply the offset to schedule training paces.

4. Splits at the Track

Track work is usually programmed as a seconds-per-400-m split. The calculator translates: 5:00/km = 5 min/km × 0.4 km = 2:00 per 400 m (120 s). For a sub-3-hour marathon (4:15/km), the same conversion gives 4.25 × 0.4 × 60 = 102 s per 400 m — useful for plugging sub-3 specific intervals into a workout plan.8:00/mile ÷ 4 = 2:00 per 400 m (120 s), since 400 m is roughly a quarter of a mile. For a sub-3-hour marathon (~6:52/mile), that works out to about 103 s per 400 m. Useful for programming a classic "10 × 400 at 5K pace" workout.

Caveats

• Hills, surface, and weather change pace at the same effort. Heart rate or perceived exertion is more honest than pace on hilly trails. The calculator gives the geometric pace; the body delivers it.
• GPS error. Watches read 1–2% long on most GPS courses, especially in cities. If your watch shows 5.10 km after a measured 5K3.17 miles after a measured 5K, the watch is the one that's off.
• Walking and running are not paced the same way. Walking pace tables exist, but the typical "minutes per km""minutes per mile" used in race calculators assumes a running gait. For walking, the conversion to speed still works, but classification thresholds are different.