Calculate your pace, speed, and predict race times using the Riegel formula.
Quick Answer:Enter your distance and finish time to see your pace per mile/km, speed, and predicted times for popular race distances.
Pace Per Mile
Calculating... min/mile
Pace Per KM
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Speed (mph)
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Speed (kph)
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Total Time
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5K
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10K
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Half Marathon
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Marathon
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The Riegel formula works best when predicting times for distances within a 2-4x range of your known distance. A recent 5K time predicts 10K well, but may overestimate marathon performance. For marathon predictions, using a half marathon time gives more reliable results. Also account for elevation, weather, and race-day conditions, which can add 5-15% to predicted times.
Running pace is calculated by dividing your total time by the distance covered. For example, if you run 5 miles in 40 minutes, your pace is 8 minutes per mile (40 / 5 = 8). This calculator converts your inputs to seconds, then divides by the distance in miles or kilometers to give pace in both units.
The Riegel formula predicts race performance at different distances using the equation T2 = T1 * (D2/D1)^1.06, where T1 is your known time, D1 is your known distance, D2 is the target distance, and T2 is the predicted time. The exponent 1.06 accounts for the fact that you slow down as distance increases. It is most accurate for distances between 5K and marathon.
A comfortable pace for most beginners is between 10-13 minutes per mile (6:15-8:00 per km). The key is to run at a conversational pace where you can speak in full sentences. As fitness improves, pace naturally drops. Most beginner 5K runners finish in 30-40 minutes, which translates to a 9:40-12:50 per mile pace.