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10K race predictor

The 10K is the classic test of speed endurance. Plug any recent race into the Riegel formula to get a realistic 10K target time and even pacing plan.

10K race predictor

Riegel formula from any recent race.

Predicted 10K time
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Enter a recent race distance and time.

Predicted pace
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Riegel exponent
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Riegel formula: T2 = T1 x (D2 / D1)^1.06. Works best when the recent race is within the last 6 weeks.
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The Riegel formula

T2 = T1 x (D2/D1)^1.06 scales a known performance to a new distance. The 1.06 exponent, fitted from world records, models the extra cost of racing longer rather than assuming linear slowdown.

Pacing a 10K off the prediction

The predicted per-kilometer pace is your even-split target. Run the first 2K a few seconds easy, settle into predicted pace through 8K, then empty the tank.

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Race Predictor 10K FAQs

What is a good 10K time?
Under 60 minutes is a solid recreational goal, under 50 is strong, under 40 is advanced. Your prediction tells you where you stand right now.
Can a 5K predict my 10K well?
Yes, this is the sweet spot for Riegel: neighboring distances predict each other accurately. A 25:00 5K suggests roughly 52:07 for 10K.
Why is my predicted 10K slower than my training runs suggest?
Training rarely replicates race day fatigue and pacing. Trust a recent race result over a great workout.
How do I enter the time?
As mm:ss, for example 52:07, or h:mm:ss for longer races like 1:52:07. The calculator parses both.
Should I race a 10K to predict a 10K?
A recent 10K is the gold standard input. Lacking that, a hard 5K time trial within the last month works well.
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