13-hour moderate effort (half marathon)
Inputs
Result
Moderate intensity = 50g carbs/hr, 24 oz fluid/hr, 467 mg sodium/hr. Total: 150g carbs over 3 hours.
Carbs/Hour
50g
Fluid/Hr
24 oz
Sodium/Hr
522 mg
Nutrition Plan
50g carbs/hr
≈ 2.0 gels/hr
Fluid/Hr
24 oz
Sodium/Hr
522 mg
Total Carbs
150g
Total Calories
600

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Inputs
Result
Moderate intensity = 50g carbs/hr, 24 oz fluid/hr, 467 mg sodium/hr. Total: 150g carbs over 3 hours.
Inputs
Result
Hard intensity + hot weather: 70g carbs/hr, 48 oz fluid/hr, 1008 mg sodium/hr.
Carb intake depends on intensity: 30g/hr for easy efforts, 50g/hr for moderate, 70g/hr for hard, and up to 90g/hr for race pace. Recent research shows trained athletes can absorb 90–120g/hr using multiple carb sources (glucose + fructose).
| Duration | Carbs/Hour | Total Carbs |
|---|---|---|
| 1–2 hrs | 30–50g | 60–100g |
| 2–4 hrs | 50–70g | 150–280g |
| 4–6 hrs | 60–80g | 300–480g |
| 6+ hrs | 70–90g | 500g+ |
Base fluid needs are 16–36 oz per hour depending on intensity. Hot weather increases needs by 30–50%. The best strategy is to drink to thirst, but plan for 4–8 oz every 15–20 minutes as a starting point.
Most athletes lose 300–700 mg sodium per hour through sweat, but heavy sweaters can lose 1,000+ mg/hr. Hot weather and high intensity increase sodium loss. Target 300–500 mg/hr in mild conditions, 500–900 mg/hr in heat.
Standard gels contain 20–25g of carbs. At 50g/hr target, that is 2 gels per hour or roughly one every 30 minutes. Mix gel types with sports drink to avoid flavor fatigue and distribute intake evenly.
Fitness and wellness calculators
Last Updated: Oct 19, 2026
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