Running Pace & Split Times Calculator
Calculate running pace per mile/km, projected finish times, and kilometer/mile split pacing for 5K, 10K, Half Marathon, and Marathon races.
Pace & Event Parameters
Projected Equivalent Finish Times (Riegel Model)
Cumulative Kilometer & Mile Splits
| Split Distance | Elapsed Time | Segment Pace |
|---|---|---|
| 1 km (0.62 mi) | 05:00 | 5:00 /km |
| 2 km (1.24 mi) | 10:00 | 5:00 /km |
| 3 km (1.86 mi) | 15:00 | 5:00 /km |
| 4 km (2.49 mi) | 20:00 | 5:00 /km |
| 5 km (3.11 mi) | 25:00 | 5:00 /km |
About this tool
How to use it
- Select your calculation mode: Calculate Pace, Calculate Finish Time, or Calculate Distance.
- Choose a standard race distance preset (1 Mile, 5K, 10K, Half Marathon, Marathon) or enter a custom distance.
- Enter your target or actual time in hours, minutes, and seconds (or your target split pace).
- Click Calculate Running Pace to view dual pace figures (/km and /mi), equivalent race time predictions, and cumulative split pacing.
Why it matters
Even pacing is the most efficient physiological strategy for distance running. Determining exact mile and kilometer split times prevents early lactate buildup from going out too fast and provides objective pacing targets for training intervals and race day execution.
When to use it
Use this calculator when planning race pacing splits, setting treadmill workout speeds, analyzing GPS watch training data, or projecting future marathon and half marathon finish times from a 5K or 10K benchmark.
Good to know
Equivalent race projections use Pete Riegel's widely validated formula (T2 = T1 × (D2 / D1)^1.06). Equivalent predictions assume adequate endurance base mileage and race-specific aerobic conditioning for the longer target distance.
Common questions
How do you calculate running pace per mile or kilometer?
Divide your total time in seconds by the total distance in miles or kilometers to get seconds per unit. Then divide by 60 to find minutes, with the remainder representing seconds. For example, a 25:00 5K (5.0 km) equals 1,500 seconds ÷ 5 = 300 seconds/km, or exactly 5:00 min/km (8:03 min/mile).
What is Pete Riegel's race time predictor formula?
Riegel's formula predicts race times across distances using the equation T2 = T1 × (D2 / D1)^1.06, where T1 is your known time, D1 is the known distance, D2 is the target distance, and T2 is the predicted time. The 1.06 exponent models the natural aerobic decay in speed as distance increases.
What is the difference between even splits and negative splits?
Even splitting means running every mile or kilometer at the exact same pace from start to finish. Negative splitting means running the second half of a race faster than the first half, which preserves glycogen stores and minimizes premature muscle fatigue.
How do I convert running pace into treadmill speed (mph or km/h)?
To get treadmill speed in km/h, divide 60 by your pace in minutes per kilometer (e.g. 5:00/km = 60 ÷ 5 = 12.0 km/h). To get treadmill speed in mph, divide 60 by your pace in minutes per mile (e.g. 8:00/mile = 60 ÷ 8 = 7.5 mph).
Why does my marathon projection feel faster than my actual race time?
Race predictors assume proper fueling, hydration, weather conditions, and that your weekly long runs and total mileage volume adequately support the distance. Without sufficient aerobic base training, muscular endurance and glycogen depletion cause greater slowdown than the theoretical formula predicts.