Marathon fueling calculatorfrom carb load to finish
Enter your weight and goal time. Get your carb load, race breakfast and a gel schedule.
Questions marathoners ask
Tap one and Alma answers
How this works, sources, and questions
How it works
The plan follows the 2016 sports nutrition position stand. Races over 90 minutes get a two-day carb load at 10 to 12 g per kg of body weight a day; shorter races get a one-day top-up at 7 to 12 g per kg. Race morning uses 2 g per kg, inside the 1 to 4 g per kg range for the 1 to 4 hours before. During the race, finishes from 75 minutes to 2.5 hours plan on 45 g an hour and longer ones on 60 g, working up to 90 g if you have practiced it. Gels assume 25 g of carbs each, spaced evenly from 30 minutes, none in the last 15.
Evidence
- ACSM, Academy of Nutrition and Dietetics and Dietitians of Canada: Nutrition and Athletic Performance (2016)
- ACSM position stand: Exercise and fluid replacement (2007)
Updated
Common questions
How many carbs should I eat during a marathon?
Most runners do well on 30 to 60 g an hour. In races past 2.5 hours, up to 90 g an hour helps if you have practiced it. That is two to three gels an hour.
How do I carb load for a marathon?
For 36 to 48 hours before, eat 10 to 12 g of carbs per kg of body weight a day. Pick familiar, low-fiber foods like rice, pasta, bread, potatoes and juice.
What should I eat the morning of a race?
1 to 4 g of carbs per kg, 1 to 4 hours before the start. Bigger meals need more time. Keep it familiar and low in fat and fiber.
When should I take my first gel?
Around 30 to 45 minutes in, then on a steady schedule. Waiting until you feel empty is too late to catch up.
How much should I drink during a marathon?
Start with 400 to 800 ml an hour and adjust for heat and how much you sweat. Drinking far more than you sweat can be dangerous, so don’t force it.
Is this a prescription?
No. It is a starting plan from the 2016 sports nutrition position stand. Practice it on long runs, and talk to a sports dietitian if you have diabetes or stomach trouble.
