Triathlon Race Nutrition Calculator
Calculate calorie and fluid needs for your triathlon race.
Get carbohydrate intake targets by race duration and intensity.
Nutrition Target
Proper race nutrition is the fourth discipline in triathlon. Getting it wrong leads to bonking (energy crash) or GI distress, both of which derail race performance.
Calorie burn rates by triathlon leg:
- Swimming: 600–800 kcal/hr
- Cycling: 500–900 kcal/hr (varies with power output)
- Running: 700–1,000 kcal/hr
Carbohydrate intake guidelines (g/hr):
- Races under 1 hour: No in-race fueling needed
- 1–2 hours: 30–60 g carbs/hr
- 2–3 hours: 60–90 g carbs/hr
- Over 3 hours: 60–90 g carbs/hr (with multiple carb sources)
Note: The human gut can absorb a maximum of ~60 g/hr of glucose alone, or up to ~90 g/hr when combining glucose + fructose sources. Over-fueling causes GI distress.
Hydration:
- General guideline: 500–750 mL per hour in moderate conditions
- Hot weather: 750–1,000 mL per hour
- Never drink to thirst alone during racing — by the time you feel thirsty, performance is already declining
Sodium: Replace 500–1,000 mg sodium per hour in hot/sweaty conditions. Sports drinks, salt capsules, or electrolyte tablets are common sources.
Practical examples:
- Sprint (1 hr): Minimal fueling — a gel before the run is enough
- Olympic (2 hr): 1–2 gels on bike, 1 gel on run, 750 mL fluid
- Half Ironman (4–6 hr): 2–3 solid snacks + 4–6 gels, 3–4 L fluid total
- Ironman (8–17 hr): Full nutrition plan with real food, gels, and drinks