Marathon Fueling: How Many Gels Does a Race Actually Need?
Running out of fuel late in a marathon is a pacing problem you can plan around. This calculator turns race time into a gel count.
What is the Marathon Fueling Calculator?
Enter your weight and expected race duration in hours. The tool plans carbohydrate at a typical range of 60 to 90 grams per hour for longer races and converts it into gels. This is a general planning guide, not medical or sports-nutrition advice: practise any plan in training first.
How to use it
- Enter your expected race time in hours.
- Enter the carbohydrate per gel you use.
- Click Plan My Fueling.
Worked example
Over 4 hours at 60 to 90 grams per hour, the total is 240 to 360 grams, which is 10 to 15 gels at 25 grams of carbohydrate each.
How many gels does a 4-hour marathon need?
About 10 to 15 gels at 25 grams each, covering 240 to 360 grams of carbohydrate at 60 to 90 grams per hour.
Frequently asked questions
Should I eat this much in my first marathon?
Build up gradually in training; jumping straight to 90 grams per hour can upset the stomach.
Does weight change the target?
This plan uses time, not weight, because gut tolerance and duration drive race-day carbohydrate needs.