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    Triathlon Fueling Calculator

    Enter how long and how hard you are going, plus the temperature and your body weight, to get your carbohydrate, fluid and sodium targets per hour. Every range comes from published sports-nutrition consensus.

    How many carbs, fluid and sodium per hour do you need?

    The answer depends mostly on how long you are out there. Under an hour, carbohydrate is not required for most sessions. Beyond an hour, take 30 to 60 g of carbohydrate per hour, and for long racing over about 2.5 hours work up toward 90 g per hour using a glucose plus fructose blend. Drink 400 to 800 ml of fluid per hour with 500 to 700 mg of sodium per litre, higher in the heat and for heavier athletes.

    Intensity sets where you land inside each range: the harder the effort, the more carbohydrate you burn, so an easy ride sits at the bottom and a threshold effort near the top. This tool is about fueling by intensity and duration. If you want a pre-race plus on-course plan built around a specific race distance, use the race nutrition planner.

    Your session

    Your hourly targets

    Enter your session details and calculate to see your targets.

    Worked example

    Athlete: 70 kg triathlete, 5.5 hour 70.3 at race pace, 20 degrees C.
    Carbohydrate: a session over 2.5 hours sits in the 60 to 90 g/hour band; race pace places it near the top, about 85 g/hour, using a glucose plus fructose blend.
    Fluid: a moderate day at 70 kg lands mid-range, about 600 ml/hour.
    Sodium: 600 ml/hour at 500 to 700 mg per litre is about 300 to 420 mg/hour from your drink. If you are a salty sweater, add tablets on top.

    Common mistakes

    • Fueling a 90 minute session like a full Ironman. Short and easy needs far less.
    • Trying to take 90 g/hour from a single carb source. Above 60 g/hour you need multiple transportable carbs.
    • Copying a heavier athlete's fluid numbers. Fluid tracks your own sweat rate, so measure it.
    • Only counting drink sodium when you sweat salt. Heavy salty sweaters need extra tablets.

    Try a calculator

    Last updated: July 2026Reviewed by: Bryan Collins, founder

    How this calculator works

    Carbohydrate targets are read from the ACSM, Academy of Nutrition and Dietetics and Dietitians of Canada 2016 Joint Position Statement (30 to 60 g/hour for exercise over an hour, up to 90 g/hour for prolonged racing with multiple transportable carbohydrates) and Jeukendrup 2014. Intensity positions the target inside the band. Fluid uses the ACSM Exercise and Fluid Replacement range of 400 to 800 ml/hour, shifted by temperature and body weight. Sodium applies the ACSM concentration of 500 to 700 mg per litre of fluid to the fluid target.

    Assumptions

    • • Carbohydrate ranges apply to exercise longer than about an hour
    • • Fluid and sodium are planning ranges; your measured sweat rate is the accurate number
    • • Intensity is a named band, not a measured power or pace

    Limitations

    • • Sweat sodium concentration varies widely between individuals
    • • Higher carb intakes require gut training over several weeks
    • • Does not account for altitude, humidity or individual GI tolerance

    Who this is for

    • • Triathletes and endurance athletes setting per-hour fueling targets
    • • Athletes fueling by session duration and intensity rather than race distance
    • • Anyone training their gut to tolerate higher carb intakes

    Who this is not for

    • • Athletes with diabetes or a clinical GI condition, who should work with a sports dietitian
    • • Children and adolescents, who have different needs

    References