Conditions · Calculator
Heat Acclimation Calculator
Build a day-by-day protocol that times your heat adaptation to land on race day, with per-session fluid and sodium targets.
EB says
10-14 days
to fully acclimate
Enter your race date and details, then build your protocol to see a day-by-day heat plan here.
Heat training
Heat acclimation FAQ
- How long does heat acclimation take?
- Most of the adaptation lands in 8 to 14 days of daily heat exposure. Athletes who already train in the heat need as few as 8 days; those coming from cool conditions need the full 14.
- How long should each heat session be?
- Sessions run 25 to 90 minutes depending on the phase. The goal is 60 to 90 minutes of elevated core temperature during the build and peak phases, not maximum intensity.
- Can I use a sauna instead of training in the heat?
- Yes. Post-exercise sauna sessions of about 30 minutes, repeated over roughly three weeks, drive similar plasma-volume gains (Scoon 2007). Use the sauna after a normal session during baseline and build days.
- How much fluid and sodium do I need during heat sessions?
- It scales with your sweat profile and measured sweat rate. The planner outputs per-hour fluid and sodium targets per phase; salty sweaters should add dedicated electrolyte capsules during build and peak sessions.
- When should I stop heat sessions before race day?
- Keep short, easy heat exposure through the final two taper days. The adaptation fades within a week without exposure, so do not stop early; drop volume, not exposure.
- Does heat acclimation help for cool-weather races?
- Yes, modestly. The plasma-volume expansion improves cardiovascular efficiency even in the cold, though the largest benefit is reserved for hot races.
- Does the menstrual cycle affect heat acclimation?
- It can. Baseline core temperature runs roughly 0.5 to 1.0F higher in the luteal phase, with a later sweat-onset threshold. Expect slightly higher perceived heat strain during luteal-phase sessions and judge intensity by effort, not the clock.
Related: Sodium Calculator and Heart Rate Zone Calculator. See also how to calculate your sweat rate, the basis for your heat fluid targets.
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