Running Pace Calculator
Work out your pace, finish time or distance. Get your speed, split times and predicted times for other race distances.
Calculate
Your pace
The formula
Pace is time ÷ distance. Speed is distance ÷ time. Predicted times use Riegel’s formula T₂ = T₁ × (D₂/D₁)^1.06 from a known race effort.
Worked example
- 10 km in 50:00
- 3,000 seconds ÷ 10 km = 300 s/km → 5:00 /km
- Speed = 10 ÷ (50/60) = 12 km/h
Result: 5:00 /km · 12.00 km/h
How pace, splits and predictions are calculated
Pace is time per unit distance; speed is distance per unit time. Splits assume even pacing. Race predictions use a simple endurance model, not a lab test.
Pace and speed
Enter any two of distance, time and pace (depending on mode) and we solve for the third. Metric mode uses kilometres and min/km; imperial uses miles and min/mile. Results always show both systems for comparison.
Even-pace splits
Splits divide total time evenly across whole kilometres or miles up to your race distance. Real races rarely stay perfectly even — use them as a planning grid, not a guarantee.
Riegel predictions
From one known performance we estimate other distances with T₂ = T₁ × (D₂/D₁)^1.06. The exponent is a common rule of thumb; longer races are often harder than the formula suggests if fueling or heat intervene.
What we do not model
No elevation, wind, treadmill calibration or VDOT tables. Heat, hills and fatigue can make a predicted marathon much slower than a fresh 10K implies.
Interesting facts
Marathon pace
A sub-4-hour marathon averages about 5:41 per km (9:09 per mile). Elite winners often finish under 2:10 — a wholly different pacing world.
Pace ≠ effort alone
Heat, hills, wind, and crowding change how a given pace feels. Use splits as feedback, not as a moral score.
Negative splits
Many coaches favor finishing the second half slightly faster than the first — it reduces early lactate buildup and late fade.
Race vs training pace
Easy runs are often 60–90+ seconds per km slower than 5K race pace. Training too hard on easy days is a common plateau trap.
Track math
On a standard 400 m track, 5:00/km is 2:00 per lap. Converting between per-km and per-mile paces prevents GPS-watch confusion.
Frequently asked questions
Divide your total time by distance. For 10 km in 50 minutes: 50 ÷ 10 = 5:00 per km. Choose Pace mode, enter distance and time, and the calculator also shows km/h and mph.
Pace is time per distance (min/km or min/mile); speed is distance per time (km/h or mph). They are inverses of each other.
Finish time needs a distance and a target pace. Distance needs a time and a pace. Switch mode at the top of the form.
We use Riegel’s formula from your current effort: T₂ = T₁ × (D₂/D₁)^1.06 for 5K, 10K, half marathon and marathon. Treat longer predictions as optimistic ceilings, not promises.
Decide a goal finish time, divide by 42.195 km (or 26.2188 miles) for average pace, then practice that effort in long runs. Add buffer for hills and weather.
GPS noise, auto-pause, and rounding differ. Course-measured distances (races) are the gold standard for official pace.
References
- Physical activity guidelines Evidence-based activity guidance for adults.
- Physical activity — WHO Global recommendations on physical activity for health.
- Running and injury prevention overview General musculoskeletal health context for active people.