A walkthrough, end to end.
- 1
Enter any two of: time, distance, pace. The third is calculated.
- 2
Toggle between km and miles. Pace is shown in min/km or min/mi to match.
- 3
See predicted splits for 5K, 10K, half marathon, and marathon at your current pace.
Pace formula
Pace is time per unit distance. To predict time at a different distance, multiply pace × distance. Most race calculators also use Riegel's formula for cross-distance prediction (this tool uses linear extrapolation; Riegel is more conservative for longer races).
What you can do with this.
Marathon pace from a half-marathon time
Linear pace × 2 is optimistic. Use Riegel: T₂ = T₁ × (D₂/D₁)^1.06. A 1:45 half ≈ 3:39 marathon by Riegel; the simple double would be 3:30.
Tempo and threshold splits
Tempo runs target ~lactate threshold pace — roughly 10K race pace plus 15 sec/mile. Use the calculator to find what your splits should look like.
Goal-pace training
Plug in your target marathon time to see what pace per km/mile you need to hold. Then run intervals at that pace until it feels sustainable.
5K pace calculator
5K race pace is roughly 105–110% of 10K pace and is an excellent VO₂ max indicator. A 22:00 5K equates to 7:05/mi — use the splits to pace your kilometre-by-kilometre effort.
10K pace calculator
10K is the longest race most runners hold close to threshold. A 45:00 10K = 7:14/mi. Negative-split pacing (slightly faster second half) tends to outperform even pacing for trained runners.
Half marathon pace
Sustainable half-marathon pace sits about 12–15 sec/mile slower than 10K. Use the splits to plan fuel stops; most runners take a gel every 5K starting at the 7K mark.
Treadmill mph to min/mile
6 mph = 10:00/mi · 7 mph = 8:34/mi · 8 mph = 7:30/mi · 9 mph = 6:40/mi. Treadmills tend to under-estimate effort by ~1–2% — set a 1% incline to match outdoor effort.
Walking pace and time
Easy walk ≈ 20:00/mi (3 mph). Brisk walk ≈ 15:00/mi (4 mph). Use the calculator to estimate how long a 5-mile lunchtime walk will take, or plan a 10K charity walk under 90 minutes.
Pace conversion: km ↔ miles
5:00/km = 8:03/mi · 6:00/km = 9:39/mi · 7:00/km = 11:16/mi. Toggle the unit selector to convert without doing the math — useful when training plans mix km and mile splits.
Pace calculator 2026 — what's standard
Modern GPS watches give moving-average pace that lags 1–3 sec behind instantaneous pace. For pacing decisions, trust the lap-pace number, not the live-pace number. Calculate target laps here, run them on the watch.
Frequently asked.
Endurance limits scale non-linearly. Pete Riegel's formula (T₂ = T₁ × (D₂/D₁)^1.06) is the standard for cross-distance prediction.
Wildly individual. Recreational runners average 9–11 min/mile. Sub-7 is competitive; sub-5 is elite. Compare against your own past performances, not absolute numbers.
Modern dual-frequency GPS (Garmin Fenix, Apple Watch Ultra) is accurate to within 1–2% on open ground. Tree cover, tall buildings, and tunnels degrade it. For interval work, use a footpod or track laps.
No. Most training time should be at easy/conversational pace (well below goal). Goal-pace work is 1–2 sessions per week — tempo runs, long-run finishers, race simulations.
Easy runs: 65–75% of max HR. Tempo: 80–87%. Threshold: 87–92%. Intervals: 92–98%. Pair the pace with HR — divergent paces and HRs tell you about fatigue.
No. Calculations happen entirely in your browser. Nothing is sent to a server, no analytics on inputs, no cookies storing your numbers.