Race Fueling Calculator
Plan your carbohydrate, fluid and sodium intake for a long race based on your expected duration.
How to use the race fueling calculator
- Enter your expected race duration.
- Choose a carb intake rate (60 g/hr is standard, up to 90 g for a trained gut).
- Click Calculate plan to see total carbs, gels, fluid and sodium.
Train your gut
High carb intake during exercise is a trainable skill. Practising race fueling in long runs improves tolerance and lets you absorb more without stomach distress on race day.
Frequently asked questions
How many carbs do I need during a marathon?
Most endurance athletes target 60–90 grams of carbohydrate per hour for efforts over about 90 minutes. Longer and faster races sit at the upper end.
How many gels should I take in a race?
It depends on duration and gel size. At 60 g/hr with 22 g gels, a four-hour race needs roughly 11 gels — plan and practise this in training.
Related tools
Marathon Pace Calculator
Enter a goal marathon finish time to get the pace you need to hold, your halfway target, and cumulative splits.
Sweat Rate Calculator
Work out how much you sweat per hour so you can plan hydration for training and racing.
Calories Burned Running
Estimate how many calories you burn on a run based on your weight, pace, and duration.