Fuel Calculator
Use this fuel calculator to estimate carbohydrate intake for endurance training and racing. It gives a simple recommended range based on session duration.
Session Duration
Recommended carbohydrate intake: --
Estimated total for this session: --
This is a simple guide.
Actual fuelling needs depend on intensity, gut tolerance, event duration and individual preference.
Why Fuelling Matters in Endurance Sport
For events lasting longer than 60 to 90 minutes, carbohydrate availability becomes a limiting factor in performance. The body's glycogen stores - held in the muscles and liver - are finite. When they deplete, performance drops sharply. Most recreational athletes are familiar with this as 'hitting the wall' in a marathon or 'bonking' on a long ride.
The solution is straightforward in principle: consume carbohydrate during the event to slow the rate of glycogen depletion and maintain blood glucose. The challenge is that gut tolerance varies between individuals, and taking in too much can cause gastrointestinal distress that is equally damaging to performance.
How Much Carbohydrate Do You Need?
Current guidance for endurance events suggests targeting 30 to 60 grams of carbohydrate per hour for efforts lasting 60 to 150 minutes. For longer efforts, athletes who have trained their gut can tolerate up to 90 grams per hour when using multiple carbohydrate sources (typically a combination of glucose and fructose, which are absorbed through different pathways).
This calculator estimates your hourly and total carbohydrate requirements based on your event duration and bodyweight. Use it as a starting point, then test your fuelling strategy in training before relying on it in a race.
Practical Fuelling Guidelines
Start fuelling early - before you feel hungry or depleted. By the time you notice the effects of low energy, blood glucose has already dropped and performance is being affected. Aim to consume small amounts regularly throughout the event rather than large amounts infrequently.
Practise your race-day fuelling strategy in training, particularly during your long runs or rides. Your gut adapts to taking on fuel during exercise, but it takes time and repetition. Race day is not the time to experiment with new products or quantities.
Struggling to get your nutrition right in training or racing? This is a common coaching focus. Explore online coaching at stevebarbour.com.