Carb Loading for a Marathon

Carb loading for a marathon made simple. Estimate race-day carb needs with the fuel planner, then practice a basic carb-loading approach.

Carb loading isn't magic, but it helps. The key is pairing a steady carb plan with practiced race-day fueling.

Simple, practical approach
Pairs with race-day gels
Works for most runners

Fueling reference

Race-day carb targets and gel counts by finish time (baseline, no body weight entered)
Race	Finish time	Carbs/hour	Total carbs	Calories	Gels
Half marathon	1:20	45 g/hr	60 g	240 kcal	2
Half marathon	1:35	45 g/hr	71 g	284 kcal	3
Half marathon	1:50	45 g/hr	83 g	332 kcal	3
Half marathon	2:05	45 g/hr	94 g	376 kcal	4
Half marathon	2:20	45 g/hr	105 g	420 kcal	4
Marathon	2:50	75 g/hr	213 g	852 kcal	5
Marathon	3:15	75 g/hr	244 g	976 kcal	5
Marathon	3:45	75 g/hr	281 g	1124 kcal	6
Marathon	4:15	75 g/hr	319 g	1276 kcal	7
Marathon	4:45	75 g/hr	356 g	1424 kcal	7
Marathon	5:15	75 g/hr	394 g	1576 kcal	7

Method and sources

The numbers on this page are computed with the same code as the TrainPace calculators, from these published methods. They are training guidance, not medical advice.

Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine 44(Suppl 1), S25–S33 — carbohydrate targets by event duration, and glucose + fructose for intakes above 60 g/hr.
Thomas, D.T., Erdman, K.A. & Burke, L.M. (2016). Nutrition and Athletic Performance (joint position statement of the ACSM, Academy of Nutrition and Dietetics, and Dietitians of Canada). Medicine & Science in Sports & Exercise 48(3), 543–568.

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