Why do cyclists need electrolytes?

Sweat contains sodium, potassium and other minerals. Losing too much sodium causes cramps, nausea and fatigue. On rides over 90 minutes, replacing electrolytes is important for performance.

How much sodium do I lose per hour?

The average cyclist loses 400-800 mg of sodium per hour in sweat. Heavy sweaters in hot conditions can lose over 1500 mg/hr. Salt stains on kit indicate high sodium loss.

Are electrolyte tablets enough?

Most tablets contain 300-500 mg of sodium. For moderate rides, one tablet per 500 ml bottle is usually sufficient. In hot conditions or for heavy sweaters, you may need higher-concentration solutions.

Can I have too many electrolytes?

Excessive sodium intake can cause bloating and GI distress. Follow your calculated needs rather than over-supplementing. Your kidneys regulate electrolyte balance, but during exercise this regulation is impaired.

What about salt capsules?

Salt capsules (200-400 mg sodium each) are useful for ultra-endurance events or heavy sweaters. Take with fluid, not dry. Start with one per hour and adjust based on how you feel.

Electrolyte Calculator — Sodium & Electrolyte Needs

Calculate sodium and electrolyte needs for long rides based on duration and conditions.

Ride Duration

Total time you'll be riding, in minutes — electrolyte loss is summed over the whole ride.

Body Weight

Your body mass — heavier riders lose more sweat and electrolytes at the same effort.

TemperatureExpected air temperature during the ride — hotter weather sharply raises sweat and sodium loss.

IntensityEffort level — harder efforts produce more body heat and a higher sweat rate.

Sweat RateHow heavily you sweat — white salt marks on your kit after a ride indicate a salty, heavy sweater.

How We Calculate This

Electrolyte Loss Calculation

Sweat rate adjusted for temperature, intensity and body mass (heavier riders lose more sweat; reference 75 kg)
Total fluid loss = Adjusted sweat rate × Duration (hours)
Sodium = ~800 mg per litre of sweat (average; range ~200–2000 mg/L, so set your own concentration if you have sweat-test data)
Potassium = ~175 mg per litre of sweat
Magnesium = ~15 mg per litre of sweat (a conservative point estimate — sweat magnesium is highly variable, roughly 10–40 mg/L between riders)
Tablets needed = Total sodium ÷ 320 mg (typical electrolyte tablet content)

Sweat rate and composition vary enormously between individuals — two riders of equal size at the same power can differ four-fold in sodium loss. Treat these figures as a starting estimate and refine with a personal sweat test.

Frequently Asked Questions

Last updated: February 2026

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.

Electrolyte Calculator — Sodium & Electrolyte Needs

How We Calculate This

Electrolyte Loss Calculation

Frequently Asked Questions

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