How many carbs per hour during a race

Count grams per hour, not gels. · 2 min read · Updated September 30, 2026

In short: Guidelines: 30–60 g of carbs per hour for efforts of 1–2.5 hours, and up to 90 g per hour beyond about 2.5 hours. A table by finish time, and how to train your gut to handle it.

How we made this guide: we built it from the research below and checked every number against it: ACSM, Academy of Nutrition and Dietetics & Dietitians of Canada joint position stand (2016); Jeukendrup, Training the Gut for Athletes (2017).

Gels differ. Most contain somewhere around 20–30 g of carbohydrate, so “take a gel every 45 minutes” adds up to different amounts depending on which one you carry. The number that matters is grams per hour.

The guideline by effort length

How long you’re running	Carbs during exercise
Under about 45 minutes	Not needed
45–75 minutes	Small amounts, or a mouth rinse (swishing a sports drink around your mouth and spitting it out)
1–2.5 hours	30–60 g per hour
Longer than about 2.5–3 hours	Up to 90 g per hour, from products that mix glucose and fructose

From the ACSM joint position stand (Thomas, Erdman & Burke, 2016).

Under ~45 minutes: none needed. 45–75 minutes: small amounts or a mouth rinse. The 60 g low end past 2.5 hours is our practical range; the guideline sets only the 90 g upper limit.

Half marathon, by finish time

Finish time	Per hour	Total for the race (approx.)
1:30	30–60 g	50–90 g
1:45	30–60 g	50–110 g
2:00	30–60 g	60–120 g
2:30	30–60 g	80–150 g

Marathon, by finish time

Finish time	Per hour	Total for the race (approx.)
3:00	60–90 g	180–270 g
3:30	60–90 g	210–320 g
4:00	60–90 g	240–360 g
4:30	60–90 g	270–410 g
5:00	60–90 g	300–450 g

For marathons we show 60–90 g/h because most finish times run past 2.5 hours; start at the lower end unless you’ve practiced more.

Your gut is trainable

Taking in carbs while running is a skill. A review by Jeukendrup (2017) describes how practicing carbohydrate intake during training improves how well athletes tolerate and absorb it. The practical version: use your race fuel on long runs, start at the lower end of the range, and increase a little every week or two.

Know how much you actually took in

After each long run, note how many grams per hour you took and how it sat. By race week you’ll know how much you can comfortably take in. We built My Track Record so logging what you ate and drank on a run is one spoken sentence, with the carbs estimated for you, which makes the grams-per-hour number easy to work out.

Keep your fueling notes without typing.
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By Andrew, founder of My Track Record. Andrew has been active all of his life across a variety of sports and continues to stay active through climbing, swimming, weight training, golfing, snowboarding, and more. He built My Track Record so logging food and training takes one spoken sentence and can support any activity. He puts these guides together from published sports science research cited on each page. About Andrew

Sources

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
Jeukendrup AE. Training the Gut for Athletes. Sports Med. 2017;47(Suppl 1):101–110. Source

General information for healthy adult runners, 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 or use caffeine.