Enter a fluid rate from repeated sweat-rate observations and a sodium concentration from the chosen drink or plan. This tool does not infer either value from a profile.
For exercise beyond about 2.5–3 hours, established guidance allows up to 90 grams per hour using practiced, multiple-transportable carbohydrate sources.
Carbohydrate
Up to 270g
Fluid
Enter a rate
Sodium
Enter both hydration values
Do not drink beyond measured sweat losses or allow body mass to increase; overdrinking can cause exercise-associated hyponatremia.
Compare evidence-aligned carbohydrate guidance by session duration, then calculate hydration totals from an athlete-entered fluid rate and sodium concentration. The planner does not infer sweat loss, sodium loss, WBGT, or heat-illness risk.
Use session duration for broad carbohydrate guidance, then enter a fluid rate from your own repeated observations and a sodium concentration from the drink or plan you intend to use. The calculator keeps those inputs independent and shows the resulting session totals.
The automatic carbohydrate result follows broad duration bands: none routinely needed under 45 minutes, small amounts for 45–75 minutes, 30–60 g/h for about 1–2.5 hours, and up to 90 g/h for longer work. A custom target above 90 g/h is intentionally separated from standard guidance.
A high sweat volume does not prove a high sweat-sodium concentration, and feeling salty does not reveal a fluid rate. Enter a chosen fluid rate from repeated field observations and the sodium concentration of the product or individualized plan. Sodium per hour is fluid liters per hour multiplied by milligrams per liter.
This planner does not infer measured sweat rate or sweat-sodium loss from a profile. It also does not estimate WBGT or heat-illness risk. Rehearse the plan in comparable conditions, avoid drinking enough to gain body mass, and seek qualified sports-nutrition or medical advice for individual needs.
The established guidance is expressed as duration-dependent ranges rather than a guaranteed best number for every athlete. The range avoids pretending that duration alone determines one precise target.
The calculator multiplies the athlete-entered fluid rate in liters per hour by the entered sodium concentration in milligrams per liter. It does not estimate either input from a qualitative sweat profile.
No. Temperature and humidity do not automatically alter the result because a generic formula cannot replace repeated sweat-rate observations, measured environmental risk, or event guidance.