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Electrolyte needs calculator

Roughly how much sodium and water to replace for a training session, based on how long and how hard you sweat.

1,200 mg sodium
Sodium to aim to replace across the session. Most sports drinks under ~500 mg/serving won't cover a hard hour.
Fluid to replace1.5 L
See our electrolyte ranking →
Educational only — a rough estimate at ~800 mg sodium per litre of sweat. Individual sweat sodium varies widely; salty sweaters need more. We ask for your sweat rate rather than your sex because sweat rate is what the maths actually depends on — and you know yours better than an average does.