Heat-Adjusted Pace Calculator
Train and race smarter in the heat. Drop in your goal pace and the conditions, and get a pace that accounts for the real cost of hot weather running.
Save your roster in the full-screen version so it sticks between visits. On iPhone Safari, storage inside an embedded page is separate, so use the Open full screen link inside the calculator.
Open the calculator full screenWhat heat-adjusted threshold pace is
Threshold pace is the fastest effort you can hold in a controlled, sustainable way, and it anchors most distance training. Heat changes the math. When temperature and humidity rise, your body sends blood to the skin to cool you down, and the same pace costs more. A threshold split that felt comfortable in April can turn into a race effort in July.
A heat-adjusted pace estimates what your intended workout should look like under today's conditions. Enter your goal pace and the weather, and the calculator returns a slower target that aims to preserve the purpose of the session: the same training stimulus, at an honest speed for the conditions.
Use the result as a starting point, not a verdict. Run the adjusted pace, then check it against how the effort actually feels. If the session still turns into a grind, slow down or shorten it. Acclimation, hydration, sleep, and recent training all shift how you respond to heat, and no formula sees those.
When not to trust it: if you feel unwell, dizzy, or unusually weak, stop. A calculator is not a heat safety clearance. And when conditions are extreme, the better adjustment is often an earlier start, a shaded route, or moving the workout entirely. For the full picture, read the guide below.