Is my 10K just double my 5K plus a minute?

Roughly, but the real slowdown is a bit more than a minute for most runners. Riegel multiplies your 5K by about 2.08 rather than a flat 2, which builds in a realistic four to five percent pace drop over the longer distance.

How accurate is a 5K to 10K prediction?

Very accurate, usually within fifteen to thirty seconds for a trained runner. The distances are close and both are mostly aerobic, so there is little room for the formula to drift.

Do I need more mileage to hit my predicted 10K?

A little. A 5K can be carried on speed, but a 10K rewards aerobic base. If your longest run is under an hour, build that up over a few weeks and the prediction becomes very reachable.

Predict Your 10K Time From a 5K

Ran a 5K lately? Enter your time to see what it predicts for the 10K, plus the pace you would need to hold.

Your 5K time

min

sec

Pace in

Predicted 10K time

45:52

That is 7:23 per mi.

Worked example

A 5K of 22:00 predicts a 10K of about 45:52, a pace of 7:23 per mi. Change the time above to run the same math on your own result.

How a 5K predicts your 10K

Going from a 5K to a 10K is the most reliable jump a race predictor makes. You are only doubling the distance, and both races sit in the same aerobic neighborhood, so Riegel’s formula barely has to stretch. For most runners the predicted 10K lands within a handful of seconds of what they actually run on a good day.

The one thing the formula assumes is that you have done a little volume. A 5K is short enough that you can carry it on speed alone, but the 10K punishes that. If your weekly mileage is low and your long run is short, expect to finish a touch slower than the prediction. Add a few easy aerobic runs each week and the gap closes fast.

Why your 10K is not just double your 5K

A common shortcut is to double your 5K and add a minute or two. That works because Riegel scales your time by the distance ratio raised to the power 1.06, not by a flat doubling. Doubling alone would assume you hold the exact same pace over twice the distance, which almost nobody does. The 1.06 exponent adds the realistic slowdown, which for this short jump is only around four to five percent per mile.

So a 22:00 5K does not predict a 44:00 10K, it predicts closer to 45:50. That extra hundred seconds is the price of distance, and it stays small here precisely because the two races are so close together.

Want every distance at once? The race pace predictor shows your time for the whole range and prints a pace band, and the VDOT calculator turns this race into your training paces.

Related predictions

5K to 10K questions

Is my 10K just double my 5K plus a minute?: Roughly, but the real slowdown is a bit more than a minute for most runners. Riegel multiplies your 5K by about 2.08 rather than a flat 2, which builds in a realistic four to five percent pace drop over the longer distance.
How accurate is a 5K to 10K prediction?: Very accurate, usually within fifteen to thirty seconds for a trained runner. The distances are close and both are mostly aerobic, so there is little room for the formula to drift.
Do I need more mileage to hit my predicted 10K?: A little. A 5K can be carried on speed, but a 10K rewards aerobic base. If your longest run is under an hour, build that up over a few weeks and the prediction becomes very reachable.