How Many Gels for a Half Marathon?

Estimate how many gels you need for a half marathon. Use your finish time to get a carb target and a simple gel schedule.

Most runners don't need a large gel load for a half, but 1-2 well-timed gels can make the last 5K feel much better.

Gel estimate for your goal time
Timing guidance
Works with drink + gel combos

How to estimate half marathon gel count

Use your goal time and intensity to decide whether you need gels and how many.

Enter goal time: Input your half marathon goal time.
Pick fueling approach: Decide gels-only or gels + sports drink.
Set timing: Use a steady schedule you practiced in training.

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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