Estimate adult electrolyte reference targets and hydration pacing during a planned fasting window.
Reference Sodium Target
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Enter sex, body weight, fast duration, and activity level to see conservative adult electrolyte reference targets.
Tap an example to prefill the calculator with sample values.
36-hour light-activity fast
165 lb adult with light activity
A moderate fasting window where baseline hydration and electrolyte awareness usually matter more than aggressive dosing.
Result: The output stays in reference-target territory with a moderate monitoring warning rather than a supplement prescription
72-hour heavier-bodyweight fast
210 lb adult with sweaty activity
A stress case showing why longer fasts and higher sweat loss quickly move into clinician-supervision territory.
Result: Hydration pacing rises, but the page leans even harder on monitoring and medical-supervision warnings