Your carb load, race breakfast and carbs per hour, for your race and body weight. Runs in your browser; nothing is saved or sent.
What this does: plans what to eat around a race, using sports nutrition guidelines. Carbohydrate is the main fuel your muscles use in a hard race, and how much you need depends on how long you’ll be out there and how much you weigh. A carb load means eating extra carbohydrate (rice, pasta, potatoes, bread, fruit) for the day or two before a long race to top up your muscles’ fuel. Tell us your race, your weight, your expected finish time and when you’ll eat breakfast, and we’ll give you the amounts for the days before, race morning, during the race and after, with simple foods that hit them.
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How it works
The amounts follow the joint position stand (an expert-panel guideline) of the American College of Sports Medicine (ACSM), the Academy of Nutrition and Dietetics and Dietitians of Canada (Thomas, Erdman & Burke, 2016): a carb load of 10–12 g per kg of body weight a day for the 36–48 hours before events over about 90 minutes; a pre-race meal of 1–4 g/kg eaten 1–4 hours before (more time, more food: about 1 g/kg for every hour of lead time); and, during the event, nothing under about 45 minutes, a little at 45–75 minutes, 30–60 g an hour for 1–2.5 hours and up to 90 g an hour beyond that. Trail and ultra races use the International Society of Sports Nutrition’s ultramarathon range of 30–50 g an hour, with fluid and sodium guidance (Tiller et al., 2019).
What real runners eat
Three elite marathoners in a case study took about 61 g of carbohydrate an hour during races, from a sports drink (Stellingwerff, 2012).
Three elite ultramarathoners ate about 70 g of carbohydrate at breakfast and about 71 g an hour during races (Stellingwerff, 2016).
Recreational marathoners ate about 59–76 g of carbohydrate at breakfast in a study of two big-city marathons (Pugh et al., 2018).
Bananas were the most common whole food runners used, alongside gels and sports drinks, in a survey of 805 Chinese distance runners (Zhao et al., 2025).
Ultra runners in a survey of 12 list bananas, dates, boiled potatoes and jam sandwiches among their go-to race foods, often with something salty on long days (Tiller et al.).
Thomas DT, Erdman KA, Burke LM. Nutrition and Athletic Performance: joint position statement of the American College of Sports Medicine, the Academy of Nutrition and Dietetics and Dietitians of Canada. Med Sci Sports Exerc. 2016;48(3):543–568. Source
Tiller NB, et al. International Society of Sports Nutrition position stand: nutritional considerations for single-stage ultra-marathon training and racing. J Int Soc Sports Nutr. 2019;16:50. Source
Stellingwerff T. Case study: nutrition and training periodization in three elite marathon runners. Int J Sport Nutr Exerc Metab. 2012;22(5):392–400. Source
Stellingwerff T. Competition nutrition practices of elite ultramarathon runners. Int J Sport Nutr Exerc Metab. 2016;26(1):93–99. Source
Pugh JN, et al. Prevalence, severity and potential nutritional causes of gastrointestinal symptoms during a marathon in recreational runners. Nutrients. 2018;10(7):811. Source
Zhao X, et al. Gastrointestinal symptoms among recreational long-distance runners in China. Front Nutr. 2025;12:1589344. Source
U.S. Department of Agriculture, Agricultural Research Service. FoodData Central (food composition database). Source
General information for healthy adults, not medical advice. If you have a medical condition, are pregnant, or have a history of disordered eating, talk to a doctor or registered dietitian before changing how you eat.