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Race nutrition & hydration
Total carbs
300 g
≈ 12 gels · 75 g/h
Total fluid
2.0 L
500 ml/h
Total sodium
1600 mg
400 mg/h
How to use it
Enter your expected finish time and flag hot weather if relevant (common for summer Caucasus races). Get a per-hour and total guide for carbs, fluid and sodium. This is a starting point — dial it in during long training runs, never try something new on race day.
Formula and source
< 75 min: carbs optional
75–150 min: 30–45 g/h
> 150 min: 60–90 g/h (75g used here)
Fluid: 500 ml/h (700 ml/h in heat) · Sodium: 400 mg/h (600 mg/h in heat)
ISSN Position Stand: Nutrient Timing (Kerksick et al., 2017); Jeukendrup, 2014 (Sports Med) — race carbs; ACSM — hydration/electrolytes
Worked example
A 4-hour marathon in heat → ≈ 300g carbs (roughly 12 gels at 25g each), ≈ 2.8L fluid, ≈ 2400mg sodium for the whole race.
Limitations
- These are ISSN/ACSM average guidelines, not medical advice — individual carb tolerance and sweat rate vary widely.
- "Hot" here is a blunt toggle — in extreme heat or high humidity, actual fluid/sodium needs can exceed this estimate.
- Always rehearse the fueling plan on long training runs first — race day is not the place to experiment with your gut.