How do I calculate my pace for a specific race?

Select 'Pace' as the variable to calculate, enter your target finish time, and choose a race distance like 'Marathon' or '5K'. The calculator will return the exact minutes and seconds per mile or kilometre needed.

What finish time will I reach at a specific pace?

Select 'Time' as the variable, enter your planned pace, and set the distance. This is useful for estimating whether a specific pace is sustainable for a half-marathon or longer event.

Can I switch between miles and kilometres?

Yes. You can toggle units for both distance and pace calculations independently to match your preferred training metric.

Are common race distances pre-set?

The distance selector includes standard presets for 5K, 10K, Half-Marathon, and Marathon, or you can enter a custom distance in any unit.

Free Running Pace Calculator

Understanding running pace

Distance, time, pace — pick any two.

The minute-per-mile vs minute-per-kilometre confusion, the marathon-pace calculation, and the Riegel formula for race time predictions.

Pace, not speed.

Runners measure performance in pace (time per unit distance) rather than speed (distance per unit time). 8-minute miles, 5-minute kilometres. Lower number = faster. Why pace and not speed? Easier mental math during a race — "I'll hit mile 5 in 40 minutes if I hold this pace" is simpler than "I'm at 7.5 mph". The metric world uses min/km; the US uses min/mile. Conversion: 1 mile = 1.609 km, so 8:00/mile ≈ 4:58/km.

pace (s/unit) = time (s) ÷ distance (unit)

The marathon math.

A marathon is 42.195 km / 26.219 miles. To finish in a target time, divide target by distance. 4-hour marathon: 240 min / 26.22 mi = 9:09/mile (5:41/km). 3-hour marathon: 180 / 26.22 = 6:52/mile (4:16/km). 2:30 marathon: 5:43/mile (3:33/km). The dividing-line paces stick in runners' heads: sub-4 = 9:09, sub-3:30 = 8:00, sub-3 = 6:52.

The Riegel formula for predictions.

Pete Riegel's 1981 race-time predictor: T2 = T1 × (D2 / D1)^1.06. Given your time T1 at distance D1, predicts your time T2 at distance D2. The 1.06 exponent captures the fatigue penalty for longer distances. A 20:00 5K predicts roughly a 41:24 10K (slightly slower per km), a 1:32 half marathon, a 3:13 marathon. The predictions are tighter for similar distances and looser for big jumps (5K to marathon predictions are routinely off by 10-15 min in either direction depending on the runner's distance profile).

A worked prediction.

A 23:00 5K predicts a half marathon time. T2 = 23 × (21.0975 / 5)^1.06 ≈ 23 × 4.47 ≈ 102.8 minutes ≈ 1:43. The runner's actual half might be 1:40 if they trained specifically for distance, 1:48 if they're a pure speed runner without endurance base. The formula gives the right zip code; the actual race time depends on training specificity.

5K → half marathon

T2 = T1 × (D2/D1)^1.06

Same fitness scaled to a longer distance.

23 × (21.1/5)^1.06 ≈ 23 × 4.47

= ≈ 1:43 half

The training-pace ladder.

Race pace is one thing; training pace is different bands. Easy/recovery runs: 60-75 % of max heart rate, ~90 seconds per mile slower than current marathon pace, the bulk of training volume. Marathon pace: as the name suggests. Threshold pace: 80-90 % effort, where lactate accumulates, ~15-20 seconds faster than marathon pace, sustained for 20-40 minutes in workouts. VO2 max pace: 95 %+ effort, ~30 seconds faster than threshold, held for 3-5 minute intervals. The ladder informs training design more than race-day pacing.

Treadmill, road, trail.

Treadmill paces don't equal road paces. The lack of wind resistance saves 5-10 seconds per mile; the moving belt does some of the leg work; the lack of stride variation reduces neuromuscular load. Set the treadmill at 1 % grade to approximately match road effort. Trail running is much slower than road for the same effort — elevation gain dominates pace; a flat 8:00 mile is a 14:00 mile on rocky uphill. Compare paces within the same surface category.

Running Pace Calculator