Heat & pace The temperature calculator
Same run.
Different temperature.
A warm day can hide a good run.
See what your time could look like
in different conditions.
Your comparison
ExampleYour run has changed. Calculate to update your comparison.
Estimated time at 10°C
24:06
54 seconds quicker3.6% less time · same distance
Your time, by temperature
°CAn estimate for the same distance and effort. Your own response to temperature may differ.
Built on real running
Millions of finish lines.
One useful comparison.
- 7.5m+
- runs analysed
- 130,000+
- runners
- 70+
- different courses
- 25,000+
- events
Behind the numbers
A little context
for your next run.
Temperature is one part of the story.
This helps you put a number on it.
What does the calculator compare?
Your finish time at two temperatures, over the same distance. It uses the overall pattern from millions of 5 km runs, comparing runners with themselves while accounting for differences between courses, seasons and other weather conditions.
Why does it start at 10°C?
10°C is the reference used in the analysis: a useful cool day to compare with. It isn’t a magic optimum. The results show relatively small differences across cooler temperatures, so chasing one perfect degree would give a false sense of precision.
Can I use it for a 10K or marathon?
Yes, as a rough guide. The evidence comes from 5 km runs. For any other distance, we apply the same percentage change to your time. Longer runs may respond differently to heat; this calculator does not estimate that extra effect.
How close will it be for me?
It’s an average adjustment, not a personal prediction or a guaranteed time. Acclimatisation, effort, sun, humidity, wind, hills and how you felt can all change your result. Evidence is thinner above 30°C. Small bumps in the chart reflect variation in the estimates.
Which temperature should I enter?
Use the air temperature around the start of your run, rather than a “feels like” reading or the day’s maximum. You can compare any two temperatures from −5°C to 35°C (23°F to 95°F).