Predict Your 15K Time From a 10K
Ran a 10K lately? Enter your time to see what it predicts for the 15K, plus the pace you would need to hold.
Worked example
A 10K of 45:00 predicts a 15K of about 1:09:10, a pace of 7:25 per mi. Change the time above to run the same math on your own result.
How a 10K predicts your 15K
The 15K is a quietly popular race distance, the Utica Boilermaker and the Gate River Run being two of the best known, and predicting it from a 10K is about as safe as predictions get. You are adding just five kilometers to a race you have already run, so the formula barely has to stretch and your fitness carries over almost directly.
Expect your 15K pace to be only a little slower than your 10K pace, on the order of a few seconds per mile. The prediction is reliable enough that you can pace a 15K straight off your recent 10K without much second-guessing, as long as the course and conditions are similar.
A short, dependable step up
Because the 15K sits so close to the 10K, the 1.06 exponent only adds a small slowdown, roughly three to four percent over the extra distance. That keeps the prediction tight. Most runners find their actual 15K lands within half a minute of the estimate, assuming they did not go out too hard early.
The main thing the extra five kilometers asks for is a slightly more patient start. The temptation is to run the opening mile at 10K effort, but holding back a few seconds per mile in the first third leaves you the strength to finish strong over the final stretch. Pace it like a long, controlled 10K and the prediction takes care of itself.
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
10K to 15K questions
- How much slower is 15K pace than 10K pace?
- Only a few seconds per mile for most runners. The 15K is just five kilometers longer, so Riegel adds a small slowdown of three to four percent and the prediction stays tight.
- Is a 10K a good way to pace a 15K?
- Yes. The distances are close and share the same aerobic demands, so you can set your 15K target straight off a recent 10K with confidence.
- How should I run the extra distance?
- Start a touch more conservatively than a flat-out 10K. Hold back a few seconds per mile early and you will have the strength to hold pace through the final kilometers.