Running Pace Calculator
Distance and time in — pace, speed, and your projected finish times for every classic race distance.
Calculate your pace
The three-way relationship
Run 5 miles in 45 minutes and your pace is 9:00 per mile (5:36/km), or 6.67 mph. The same arithmetic projects finish times: that pace yields a 27:58 5K, a 55:56 10K, just under 1:58 for a half marathon — though projections to longer races are optimistic, because nobody holds 5-mile pace for 26.2 miles without specific training.
Predicting race times honestly
The flat-pace projections above assume identical effort across distances, which physiology declines to provide. Runners typically slow ~5–6% each time distance doubles (the basis of Riegel's prediction formula). Practical reading: your 5K pace minus ~20–30 seconds per mile approximates 10K pace; add ~30–40 seconds to 10K pace for half-marathon pace. The longer the target race, the more the prediction depends on your weekly mileage rather than your speed.
Using pace in training
Most effective training happens slower than race pace: the standard structure puts roughly 80% of weekly running at a conversational pace — often 60–90 seconds per mile slower than 5K pace — with the remaining 20% as quality work (tempo runs near one-hour-race effort, intervals at 5K pace or faster). Runners who do every run at medium-hard pace plateau; the easy/hard split is the most reliable improvement lever in the sport. Use this calculator to find your zones, then have the discipline to actually run the easy ones easy.
Frequently asked questions
What's a good pace for a beginner?
Whatever pace lets you finish the distance comfortably — commonly 10–13 minutes per mile, often with walk breaks. Pace improves automatically with consistent weeks; chasing speed first is how beginners get injured.
How do treadmill paces compare to outdoor?
Treadmills remove wind resistance, so the same setting feels slightly easier; a 1% incline approximates outdoor effort. Treadmill calibration also varies — trust effort and heart rate over the display.
How accurate are the marathon projections?
Flat-pace extrapolation flatters you. From a 5K time, a realistic marathon is closer to your pace plus 45–60+ seconds per mile, and only with marathon-specific training volume. Race predictors like Riegel's formula bake in the slowdown.
What pace do I need for a sub-30 5K or sub-4 marathon?
Sub-30 5K: 9:39/mi (6:00/km). Sub-25: 8:03/mi. Sub-2 half: 9:09/mi. Sub-4 marathon: 9:09/mi as well — held for twice as long, which is the whole sport in one sentence.