Carbs Per Hour Calculator
For efforts over 90 minutes, most endurance athletes need 60 to 90 grams of carbohydrate per hour, and trained guts can reach 120. This calculator turns your event duration, intensity, body weight, and gut training level into a per-hour target, a glucose to fructose split, and an hour-by-hour fueling plan for running or cycling.
This is the in-race target. To pre-load glycogen the day before, use the carb loading calculator; to build the bottle itself, use the DIY sports drink calculator.
Gear up
Race fuel athletes actually carry
Aim for a 2:1 glucose to fructose source above 60 g/h. Test any new product in training first, never on race day.
- Energy gels (multipack)About 22 g carbs each. The simplest way to hit a steady per-hour target on the run or bike.View on Amazon →
- Dual-source carb drink mix (2:1 glucose fructose)Pre-blended glucose and fructose so you can push past 60 g/h without a single-transporter ceiling.View on Amazon →
- Maltodextrin + fructose powdersBuild your own bottles for pennies and dial the exact 2:1 ratio this calculator recommends.View on Amazon →
- Bike top-tube fuel bagKeep an hour of gels and chews within reach so you actually feed on schedule.View on Amazon →
As an Amazon Associate we earn from qualifying purchases.
Build the bottle
DIY Sports Drink Calculator
Turn your per-hour target into an exact maltodextrin and fructose bottle recipe at a 2:1 ratio.
Load up first
Carb Loading Calculator
Top off glycogen the day before so you start the race with a full tank, then fuel to this per-hour plan.
Carbs per hour calculator FAQ
How many carbs per hour should I eat when cycling or running?
For efforts longer than about 90 minutes, aim for 60 to 90 grams of carbohydrate per hour, taken as roughly 20 grams every 20 minutes. Shorter sessions under 90 minutes need little or nothing beyond water. Trained athletes who have practiced high-carb fueling can absorb up to 120 grams per hour. Running tolerates slightly less than cycling because the gut is jostled more, so build up gradually and test every number in training before race day.
Why split carbs between glucose and fructose?
Your gut absorbs glucose (and maltodextrin) through one intestinal transporter that saturates near 60 grams per hour. Fructose uses a separate transporter, so adding it lets you absorb more total carbohydrate without the leftover sugar sitting in your gut and causing distress. Above 60 grams per hour, a 2:1 ratio of glucose to fructose is the well-supported split, which is why most modern gels and drink mixes are formulated that way.
Can I really absorb 120 grams of carbs per hour?
Some trained athletes can, but only after deliberate gut training. The intestinal transporters that move carbohydrate into the blood are trainable: repeatedly fueling at high rates in training raises how much you tolerate without stomach upset. An untrained gut that suddenly tries 120 grams per hour on race day usually ends in nausea or worse. Start near 60 grams per hour, add roughly 10 grams per hour every couple of weeks, and always use a 2:1 glucose to fructose source at the high end.
Do I need to fuel for a race under 90 minutes?
Generally no. Your muscles store enough glycogen to cover hard efforts up to about 90 minutes, so a 10K, a short sprint triathlon, or a one-hour ride does not require mid-race carbohydrate beyond water. For efforts right at the 90-minute line, a small amount of carbohydrate or even a carbohydrate mouth rinse can help. The payoff from carrying fuel grows quickly once you cross into two-hour-plus territory.
Is the per-hour carb target different for running versus cycling?
The underlying absorption limits are the same, but practical tolerance differs. Cycling is smooth and lets the gut handle the upper end of the range comfortably, so many cyclists fuel at 90 grams per hour or more. Running adds impact and gut jostling, so runners often sit a little lower and lean on liquids and gels rather than solid food. Either way, the duration of the effort, not the sport, is the biggest driver of how much you need.
How do I convert grams per hour into gels and drinks?
A standard energy gel holds about 22 grams of carbohydrate, so a 60 gram per hour target is roughly three gels per hour, or two gels plus a carbohydrate drink. A typical drink-mix scoop holds 20 to 30 grams. Spread intake into a feed every 15 to 20 minutes rather than one large dose, and always wash gels down with water to help absorption and avoid a concentrated sugar load sitting in the stomach.
See also: how many carbs per hour for cycling and running.
Feedback
Missing something?
Tell us what you'd like to see added to this tool.