Use the Race Day Fueling Calculator to generate your personalized targets. It will give you two key numbers to follow every hour:Hydration per hour: your recommended fluid intake in mL per hour, based on your sweat rate and conditions. As a general guide, most athletes land around 400 to 1,000 mL per hour, with hotter or more humid days pushing that higher.Carbs per hour: your recommended carbohydrate intake in grams per hour, based on race length and what you can tolerate. A common endurance range is 60 to 90 g per hour, and some well trained athletes can handle 90 to 120 g per hour when using mixed carb sources and a practiced gut.
Once you run the calculator, follow those hourly targets consistently from early in the race, not just when you feel thirsty or hungry.