Electrolyte Replacement Calculator
Estimates sodium and potassium replacement per hour for hot-weather exertion.
Inputs
Result
A natural placement between the calculator and the explanation.
What this solves — and what it doesn't
Heat cramping and exercise-associated hyponatremia are both electrolyte problems. Salt tablets, sports drinks, or electrolyte mixes are not optional in hot-weather endurance — water alone can dilute blood sodium to dangerous levels. This tool estimates how much sodium and potassium you lose in sweat over a given effort and conditions, so you can plan replacement.
How to read the result
The ‘per hour’ numbers are your planning rate. Match them with intake (sports drink + salty snacks, or salt tabs).
Potassium is rarely the limiting factor in a hot day; sodium usually is.
Limitations
- Sweat rate is a guess — individual sweat sodium concentration varies 4x across people.
- Doesn’t model acclimatization (which reduces sodium concentration).
- Heavy sweaters in heat can lose 1.5+ g Na/h; our ‘heavy’ estimate is conservative.
Frequently asked questions
Is water alone enough?
In cool weather and short efforts, yes. Above 90 minutes in heat, no. Drink electrolytes, not just water.
What is the danger of too much water?
Exercise-associated hyponatremia. Drinking plain water faster than you sweat dilutes blood sodium; can be fatal.
Are salt tabs safe?
Yes, when used to match sweat losses. ~1 tab (1 g) per hour in heavy heat is a common regimen.