How much carbohydrate do athletes need per hour?

To perform at their best, most endurance athletes need 30 to 90 grams of carbohydrate per hour during exercise, with the right target dictated mainly by duration and intensity: under 1 hour usually needs little or no carb, 1-2 hours benefits from 30-60g/h, and 2+ hours benefits from 60-90g/h, whilst trained athletes can push beyond 90g/h.

The higher the intensity of exercise, the more carbs are likely to be needed to support optimal performance.

Key takeaways

• Under 1 hour, starting well-fueled: carb intake is generally unnecessary. A carb mouth-rinse may help all-out efforts at 45-60 minutes, if pre-exercise fueling hasn't been optimal.
• 1-2 hours: aim for 30-60g of carbohydrate per hour, scaling toward 60g as duration and intensity increase
• 2+ hours: aim for 60-90g per hour. 120g/h is achievable for athletes who have trained their gut (Viribay et al., 2020)
• Body size matters, but less than gut absorption rate. Evidence suggests that athletes over 70kg may be able to oxidise roughly 13g/h more glucose than smaller athletes (Ijaz et al., 2024)
• Above ~60g/h, use a glucose-fructose blend (multiple transportable carbohydrates) to increase the amount of carb your gut can absorb
• Train your gut over 4-6 weeks of progressive intake to expand your tolerable range

Use the Fuel & Hydration Planner to calculate your numbers

Why is the amount of carb more important than the type?

The confusion around how much carbohydrate athletes need is partly created by decades of sports nutrition marketing that has muddled our priorities - putting the proverbial cart before the horse.

Many brands focus on the source of carbohydrate in their products rather than how much you should be taking in or whether the format (a gel or a drink, say) suits your individual situation. There's a near-constant hype cycle around the latest formulation: 'Hydrogel Technology', 'Cluster Dextrin™', 'SuperStarch'. This isn't because source is the most important factor, but because it offers a way for otherwise similar products to be differentiated in a crowded marketplace.

There's much less discussion about how to figure out how many grams of the stuff you actually need to put in your mouth - despite that being the more important question. The most we usually get is generic advice like "Take one to three servings per hour during exercise."

Maslow's Hierarchy of Needs is helpful here. In Maslow's pyramid, our most fundamental needs as humans (food, water, warmth) sit at the base. Only once those are met do we benefit from worrying about higher-order needs like belonging, esteem, or self-actualisation.

Fueling works the same way. The base of the hierarchy is the right amount of carbohydrate per hour, in a format that works for your sport. The source of that carb is a higher-order concern that becomes relevant only once you're consistently nailing the basics.

This doesn't mean source is irrelevant - at high intakes (above ~60g/h) it matters quite a bit. But it's not where most athletes' performance is being lost.

Why do you need carbs during longer, harder exercise?

Glycogen — chains of glucose molecules stored in your muscles and liver - provides much of the carbohydrate that fuels the early part of any bout of exercise. Think of it as your current account for energy, with fat being more like your savings for a rainy day.

Like the money in most people's day-to-day account, glycogen is a finite resource. 90-120 minutes of hard activity will generally deplete your stores enough to significantly compromise your performance.

So at some point, taking in carbs (drinks, gels, chews, bars, real food) is either helpful or absolutely necessary to maintain a high level of output. Relying on fat for fuel doesn't allow for the level of effort associated with racing hard and fast.

Carbohydrate ingested during exercise is known as 'exogenous' fuel - extra cash in your hand while you're out spending hard. Because of the performance-enhancing potential it holds, the exact amount and type of exogenous fuel to consume has been the subject of much research and trial and error over the last 50 years.

The good news for the modern athlete is that, once you cut through the hype, there are clear, tried-and-tested guidelines for how much carb you need to consume to optimise performance over different durations and intensities.

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Two important assumptions before the numbers:

1. You'll be starting exercise with robust glycogen stores - meaning you've had a light, carb-dense meal or snack 2-3 hours before the workout or race . If that's not the case, your in-race requirements may be higher (if tolerable) because your tank is partly empty before the gun goes off.
2. The recommendations are for optimising performance, not just getting round. That implies you're pushing hard for the duration - as in a competitive setting. The same rules don't apply to fueling an easy 2-hour training ride at conversational pace; lower intensities use far more fat, so exogenous carb requirements drop accordingly.

With those covered, let's look at the targets.

How much carb do you need for exercise under 1 hour?

In almost all cases, athletes starting well-fueled don't need to ingest carbohydrate during activities lasting less than an hour. Your glycogen stores have you covered, and they typically just benefit from being topped up with a sufficiently carb-rich recovery snack afterwards.

That said, intensity and exact duration matter:

• Under 30 minutes: carbohydrate ingestion has been shown to have little-to-no effect on performance outcomes.
• 45-60 minutes at all-out intensity: there's some evidence that performance benefits from a small amount of carbohydrate ingestion, or a carb mouth-rinse — which can be more convenient during intensive racing when swallowing is awkward. It's important to note that the majority of these studies were done on athletes in a fasted or depleted state though - so a carb mouth rinse is less likely to be effective at this duration if you've carb loaded sufficiently pre-exercise.

A carbohydrate-rich drink is the best choice for these hard, fast efforts because it's easier to consume (or to 'swish and spit') than a gel, bar or a slice of pizza.

How much carb do you need for 1-2 hours of exercise?

As duration increases, so does the benefit of exogenous fueling. In this 1-2 hour window, carbohydrate ingestion will almost certainly significantly improve your performance.

Aim for 30-60 grams of simple carb per hour. This equates to about 500ml-1 litre (16-32oz) of a 'standard' isotonic (~6% carb) energy drink, or about 1-2 standard energy gels per hour (or a combination of the two).

The harder the work and the longer the duration within this bracket, the more appropriate it is to push toward the upper end (~60g/h). This is especially true for athletes who are extremely fit and able to sustain very high workloads.

Beyond two hours, research generally points toward a solid dose-response relationship: higher carb intakes elicit better performance outcomes.

Try the PF 30 Gel — exactly 30g of carbohydrate per serving, designed for this duration band

How much carb do you need for 2+ hours of exercise?

Athletes significantly going past the 2-hour mark can benefit from higher intakes of 60-90 grams of carbohydrate per hour, as long as the amount consumed doesn't cause stomach problems. Faster competitors in long races tend to have the highest carbohydrate intake rates — which is why we're routinely impressed with the eating done by the Tour de France riders and IRONMAN winners we work with. Racing long distances at a fast pace is as much an eating event as it is an athletic one.

The higher the target, the more crucial 'training your gut' becomes. An hourly intake of ~90g/h (3 x PF 30 Gels, 3 x PF 30 Energy Chews, or 1 x PF 90 Gel) is not something all athletes can achieve immediately. It can take weeks or months to build up, especially if you've been prone to GI issues.

Significantly, this is also where the source of your carbohydrate starts to matter. Above ~60g/h, multiple transportable carbohydrates (MTCs) — typically glucose-fructose blends — improve absorption by using more than one of the gut's transport pathways.

Try the PF 90 Gel - a glucose-fructose blend delivering 90g of carb in a single serving, designed specifically for high-intensity work past the 2-hour mark

How high can carb intake actually go?

For a long time, ~90g/h was considered something of a firm ceiling. That ceiling has moved.

Trained athletes are routinely sustaining 100-120g/h in elite competition, and the science has caught up: Viribay et al. (2020) found that 7 of 9 trained runners tolerated 120g/h with no GI issues, with measurable benefits in internal load and reduced muscle damage markers. Our own Case Studies conducted on hundreds of elite athletes across triathlons, cycling races, marathons and ultra-marathons routinely show intakes well over 100g per hour as well.

The practical message: 90g/h is no longer a hard ceiling for athletes who've put the gut training in. But it's still a meaningful target to work toward — and most amateur athletes don't need to chase the 120g/h frontier to unlock real gains.

When exercise goes 'ultra' (often 6+ hours), additional considerations come in: real food might help with flavour fatigue and contributes some fat and protein, and total daily intake matters more than any single hour's number when you're going fully 'round the clock'. (See How much carb should you eat before, during and after an ultra for more.)

Does body size affect how much carbohydrate you need?

The intuitive answer is yes — surely a bigger athlete burning more energy needs more carbohydrate. The reality is more nuanced.

The traditional view, reflected in most blanket recommendations, is that body size doesn't really matter because gut absorption is the rate-limiting factor and absorption rates are similar across athletes of different sizes. That's true in broad strokes — which is why our 30-60-90g/h framework is expressed in absolute grams, not per kilogram of bodyweight.

But the picture has refined. A 2024 study (Ijaz et al.) found that athletes over 70kg oxidise roughly 13g/h more glucose than athletes under 70kg. That means blanket recommendations may slightly underfuel large athletes and may sit at the upper end of what smaller athletes can comfortably use.

Two practical implications:

• If you're notably above 70kg (154lb) and racing hard for hours , you may benefit from sitting toward the high end of the 60-90g/h range — and from prioritising gut training to push higher.
• If you're notably below 70kg (154lb), you may not need to chase the very top of the range to be fully fueled. Athletes with lower body mass may theoretically also get a relatively greater performance benefit from any given dose of exogenous carbohydrate, because that dose represents a larger share of their total energy expenditure.

Body size is no longer the irrelevant factor it was once made out to be — but it's still a secondary lever after duration and intensity.

What does 30, 60, or 90g of carb per hour actually look like?

How you get the carbs in is a personal matter, and there are many options — sports-specific fuels (gels, chews, bars, drink mix) and real food. The pros and cons of each warrant their own discussion, but as long as what you take agrees with your digestive system and works practically for your sport, there are few hard right or wrong answers.

The key is delivering roughly the right amount per hour to address your energy needs.

Typical carb content of common fuel sources:

Typical carb content of common fuel sources:

The Fuel & Hydration Planner is built to help you set your numbers for a specific event. Use it to work out how much carbohydrate (and fluid, and sodium) you're likely to need for the intensity and duration of your chosen activity.

Get a free race nutrition plan

Our PF 30 Gel, PF 90 Gel, PF 300 Flow Gel, PF Chews, Carb & Electrolyte Drink Mix and Carb Only Drink Mix all state the carb dose per serving on the front of the packet, so you can hit your numbers without guesswork during training or racing.

How do you train your gut to handle more carbohydrate?

If you're regularly experiencing GI distress or struggling to consume enough carbohydrate for the duration and intensity you're racing at, your gut is the bottleneck — not your willingness or your product choice.

The good news: gut tolerance is trainable. Cox et al. (2010) showed that daily training with high carbohydrate availability increases your body's exogenous CHO oxidation. In practice, this means progressively pushing your intake during one or two hard sessions per week, over a period of 4-6 weeks, until your tolerable ceiling moves up.

A practical starting protocol:

1. Establish your current ceiling. What's the highest hourly carb dose you can comfortably consume during a hard session today?
2. Pick one or two hard sessions per week that mimic race-day intensity for a meaningful duration.
3. Increase intake by ~10g/h every 1-2 weeks , holding at the new dose until it feels comfortable.
4. Use multiple transportable carbohydrates (glucose-fructose blends) once you're above ~60g/h.
5. Practise with the products you'll race with — gut tolerance is partly product-specific.

Trained gut, trained taste buds, trained logistics. None of these happen on race day; they happen across the build-up.

Frequently asked questions

How much carbohydrate per hour do I need for a marathon? For most marathoners, 60-90g/h is the right target. Faster finishers (sub-3 hours) push toward the upper end and benefit most from intakes around 75-90g/h. Slower finishers (4+ hours) can sit comfortably in the 45-60g/h range and still optimise performance.

Is 90g of carbohydrate per hour the maximum? Not anymore. 90g/h was the rule of thumb for years, but Viribay et al. (2020) and elite-athlete data have established that 100-120g/h is achievable for athletes who train their gut. Most amateurs don't need to chase that frontier — but the ceiling is no longer fixed.

Does it matter what type of carbohydrate I use? Below ~60g/h, total amount matters far more than source. Above ~60g/h, a glucose-fructose blend (multiple transportable carbohydrates) lets your gut absorb more by using more than one transport pathway.

Should bigger athletes consume more carbohydrate per hour? Slightly. A 2024 study (Ijaz et al.) found athletes over 70kg oxidise about 13g/h more glucose than athletes under 70kg. The 30-60-90g/h framework still holds, but bigger athletes may benefit from sitting toward the top of each band.

How long does it take to train your gut for higher carbohydrate intakes? Plan for 4-6 weeks of progressive intake during one or two hard sessions per week. Push your hourly dose up by ~10g every 1-2 weeks until you reach a comfortable new ceiling.

Can I just use real food instead of sports nutrition products? For lower-intensity exercise and ultra-endurance events, yes — and real food helps with flavour fatigue. For high-intensity racing in the 1-4 hour window, sports nutrition products are usually more practical because they deliver predictable carbohydrate doses in formats your gut can absorb quickly.

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Further reading

• How to choose the right energy product format to fuel your performance
• Does the type of carb in your energy products really matter?
• Should you use carbs or fat to fuel endurance exercise?
• What happens when you 'bonk'? (And how to avoid it!)
• How to train your gut to handle more carbohydrate

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References

1. Cox GR, Clark SA, Cox AJ, Halson SL, Hargreaves M, Hawley JA, Jeacocke N, Snow RJ, Yeo WK, Burke LM. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. Journal of Applied Physiology . 2010;109(1):126–134. doi: 10.1152/japplphysiol.00950.2009
2. Ijaz H, Collins J, Moreno-Cabañas A, Bradshaw E, Hutchins K, Podlogar T, Wallis GA, Gonzalez JT. Exogenous glucose oxidation during exercise is positively related to body size. International Journal of Sport Nutrition and Exercise Metabolism . 2024 (ahead of print). doi: 10.1123/ijsnem.2024-0097
3. Jentjens RLPG, Jeukendrup AE. High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise. British Journal of Nutrition . 2005;93(4):485–492. doi: 10.1079/BJN20041368
4. Jeukendrup AE. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine . 2014;44(Suppl 1):S25–S33. doi: 10.1007/s40279-014-0148-z
5. Podlogar T, Wallis GA. New horizons in carbohydrate research and application for endurance athletes. Sports Medicine . 2022;52(Suppl 1):5–23. doi: 10.1007/s40279-022-01757-1
6. Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro A, Seco-Calvo J, Urdampilleta A. Effects of 120 g/h of carbohydrates intake during a mountain marathon on exercise-induced muscle damage in elite runners. Nutrients . 2020;12(5):1367. doi: 10.3390/nu12051367