Hydration & fuel calculator
Build a personalised hydration and fuel plan—water, sodium, and carbs—from session length, effort, sweat rate, and heat. The same multi-step approach used by popular electrolyte calculators, tuned for runners in Indian conditions. Educational estimate only—not medical advice.
How long is your session?
Choose the option that best matches your workout duration.
Enter a session longer than 0 minutes.
How intensely will you be running?
Harder efforts raise sweat and sodium loss—even in the same weather.
How much do you generally sweat?
This helps estimate how much fluid and sodium you lose each hour.
Where will you be running?
Heat drives fluid loss. Pick a city preset or enter temperature manually.
Your hydration & fuel plan
Hydration
- Water
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- Sodium
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Before activity (30–45 min before)
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During activity (every 15–20 minutes)
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After activity (within 30 minutes)
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Nutrition (carbs)
- Carbs during run
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- Total carbs (session)
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Before activity (30–60 min before)
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During activity
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After activity (within 30–60 minutes)
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Mix electrolytes in water as labelled (~500 mg sodium per typical serving). For runs over ~60 minutes, aim for 30–90 g carbs per hour depending on effort—gels (~25 g), bananas (~25 g), or sports drink (~30 g per 500 ml). In heat, favour cool fluids and don’t wait until you’re thirsty on long efforts. Pair with our heat & humidity pace calculator.
Frequently asked
How is water per hour estimated?
Base fluid ranges depend on sweat rate × intensity (about 300–800 ml/hr), then scale for weather (cold / moderate / hot) and session length. Results round to 50 ml steps and display as litres per hour.
How is sodium estimated?
Light / average / heavy sweaters start from different hourly sodium loss bands. Duration, heat, and intensity multiply that range. Values show as mg/hr; ~500 mg ≈ one typical electrolyte serving.
What counts as “hot” weather?
Below 15°C is treated as cool, 15–25°C as moderate, and above 25°C as hot for fluid multipliers—matching common outdoor running conditions across Indian cities.
How are carb needs estimated?
Runs under 45 minutes usually need little or no fuel during the session. From ~60 minutes upward, typical guidance is 30–60 g carbs/hr at moderate effort, rising toward 60–90 g/hr for sessions over 2.5 hours or all-out racing. Harder intensity and heavier sweating nudge estimates toward the upper band. Values round to 5 g steps and show practical equivalents (gels, bananas, sports drink).
Is this medical advice?
No. Individual sweat sodium and carb tolerance vary widely. If you have kidney, heart, diabetes, or electrolyte disorders—or race in extreme heat—consult a clinician or sports dietitian.