How to Use Sweat-Rate + Electrolyte Marathon Plan
The Sweat-Rate + Electrolyte Marathon Plan converts your measured sweat rate and target finish time into a race-day fluid and sodium replacement schedule. Enter your sweat rate from a pace-matched training run alongside your estimated finish time; the tool returns total fluid requirements, per-hour intake targets, and sodium replacement amounts matched to aid station intervals on your course.
What It Does
Use the calculator with intent
The Sweat-Rate + Electrolyte Marathon Plan converts your measured sweat rate and target finish time into a race-day fluid and sodium replacement schedule. Enter your sweat rate from a pace-matched training run alongside your estimated finish time; the tool returns total fluid requirements, per-hour intake targets, and sodium replacement amounts matched to aid station intervals on your course.
Athletes, coaches, and AI agents who need a quick, reproducible answer with named limitations rather than a generic estimate.
Interpreting Results
The hero number is your estimated total fluid requirement across the marathon distance. Read the secondary stats for per-hour intake targets and sodium replacement amounts — the electrolyte figures are often more important than total fluid volume because hyponatremia risk rises when plain water is consumed without sodium replacement. Match the per-hour targets to aid station intervals on your specific course to build your race-day plan.
Input Steps
Field by field
- 1
Enter inputs
Enter your values using the sliders and steppers. Defaults represent a reasonable midpoint.
- 2
Read outputs
Read the hero number first. Secondary stats provide context and ranges.
- 3
Follow
Follow the methodology link for formulas, coefficients, and citations.
- 4
Adjust parameters
Adjust each input one at a time to see how the hero number responds.
Enter your sweat rate from a training run done at or near your marathon goal pace — effort intensity and pace affect sweat rate, and a rate measured at easy-run effort will underestimate race-day fluid loss.
Common Scenarios
Use realistic starting points
FAQ
Questions people ask next
The short answers readers usually want after the first pass.