Heat-adjusted pace calculator
Heat and humidity slow every runner — the only question is whether you adjust on purpose or fade by accident. Add the temperature to the dew point; that sum sets the pace penalty. No login, no catch.
Adjusted pace
9:35/mi
temp + dew = 146 → 4.5% slower
| Distance | Heat cost at this pace |
|---|---|
| 5K | +1:17 |
| 10K | +2:34 |
| Half marathon | +5:24 |
| Marathon | +10:49 |
How it works
The adjustment uses the temperature-plus-dew-point chart popularized in marathon coaching: dew point matters as much as temperature because it controls how well sweat evaporates. Our training plans apply this exact table to every prescribed workout, every night, from the next day's forecast.
| temp°F + dew°F | Pace adjustment |
|---|---|
| ≤ 100 | 0% |
| 101–110 | 0.5% |
| 111–120 | 1.0% |
| 121–130 | 2.0% |
| 131–140 | 3.0% |
| 141–150 | 4.5% |
| 151–160 | 6.0% |
| > 160 | 8.0% |
Interval sessions get roughly half the penalty (you re-cool between reps). Racing? Every race page on Marathon Compass shows this math against the race's own 10-year weather history — see the race catalog or check whether you could finish a marathon.