Race Nutrition and Hydration Calculator
Calculate your carbs, hydration and electrolyte needs. Get a complete intake plan for your next race.
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Intake schedule
Race nutrition: the fundamentals
Nutrition is a cornerstone of endurance performance. Beyond 1 hour of effort, the body needs a carbohydrate intake to maintain intensity. Current scientific recommendations are 30 to 90g of carbohydrates per hour depending on the duration and intensity of the effort.
The most common mistake is not fueling early enough during the race. The digestive system takes time to absorb nutrients — it is recommended to start fueling within the first 30 to 45 minutes of effort for races lasting more than 1h30.
How many gels per race?
An energy gel provides an average of 25g of carbohydrates. The number of gels therefore depends on the duration of your race and your carbohydrate needs per hour. For a half marathon in 1h45, 2 to 3 gels are enough. For a marathon in 4h, plan for 5 to 7 gels. For an ultra-trail of 10h+, you will need to alternate between gels, bars and solid food.
Frequently asked questions
How many gels for a half marathon?
For a half marathon (1h30 to 2h30), plan for 2 to 4 energy gels depending on your duration and level. Take the first gel around 30-45 min, then one every 30-40 min after that. Accompany each gel with a few sips of water.
How much hydration for a 30 km trail?
For a 30 km trail (3h to 5h of effort), plan for 500 to 750 ml of water per hour in temperate conditions. That is 1.5L to 3.5L total. An isotonic drink is preferable to water alone as it provides carbohydrates and minerals.
Should I take electrolytes?
Yes, especially in hot weather (above 25°C) and for efforts lasting more than 2 hours. Sweating causes sodium loss (300 to 1000 mg/h depending on the individual). Electrolyte tablets or isotonic drinks help compensate for these losses.