A science-backed tool to help runners, cyclists, and endurance athletes fuel right—based on your training, not your body weight.
If you’ve ever asked, “How many carbs should I take per hour during exercise?”—you’re not alone. The answer depends on how long you’re going, how hard you’re pushing, and how well your gut can handle the fuel. That’s where the XACT Carb Calculator comes in.
Built with the latest sports science, this free tool gives you clear, actionable fueling guidance for training, racing, and everything in between.
What Does the XACT Carb Calculator Do?
When you enter two simple details:
- Your session’s intensity
- Your session’s duration
…you get three key recommendations:
- How many grams of carbohydrates per hour you need
- What form those carbs should take — liquid, gel, or solid
- Whether you should train your gut to better absorb carbs
These aren’t just nice-to-know. They’re what fuel real performance—and the difference between bonking and breaking through.
Why Body Size Doesn’t Determine Carb Needs
You might be surprised that the calculator doesn’t ask for your weight. That’s no accident.
During exercise, carb needs aren’t proportional to body size. Research shows a 60 kg runner and an 80 kg cyclist can require the same amount of carbs per hour to perform at their best.
And while heat or altitude might affect comfort, they don’t significantly change how many carbs your body can absorb during exercise. That’s why the XACT Carb Calculator keeps it simple: it focuses on intensity and duration—the two best predictors of energy needs.
Gels, Chews, or Drinks? It’s All About What You Tolerate
One of the most common questions we get is: “Which is better—gels, chews, or sports drinks?”
The answer? Your body doesn’t care.
In controlled studies, athletes absorbed carbs just as effectively from liquids, gels, or solids—with no difference in performance outcomes.
What does matter is gut comfort:
- For high-intensity efforts: a drink or gel might go down easier.
- For long, steady workouts: chews or bars are often more satisfying.
The Carb Calculator helps you choose the best form of carbs for your effort, based on what you’ll tolerate best.
Why Gut Training Can Change Your Game
Ever feel bloated, crampy, or gassy when fueling during a race? You’re not alone—and it doesn’t mean your stomach is broken.
Your gut is trainable, just like your muscles.
If the calculator flags that gut training might help, it’s not a critique—it’s an opportunity. Here’s why it matters:
- Without gut training, a portion of your carbs never makes it to your muscles.
- With structured training, carb malabsorption can drop by up to 54%.
- GI symptoms like cramping or bloating can be reduced by almost half.
Even your gut bacteria adapt, becoming more efficient at processing fuel.
How to Train Your Gut (and Make the Most of Every Gram)
If your calculator result suggests gut training, here’s your playbook:
- Start Small: Begin with 30–40g of carbs/hour during training.
- Build Gradually: Increase by 10–15g/hour every 7–10 days.
- Simulate Race Day: Match your race-day intensity and duration.
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Be Consistent:
- Practice gut training 1–2 times per week
- Use the same nutrition products you’ll use in competition (like XACT Energy fruit bars or XACT PROTEIN squares)
Within 2–4 weeks, most athletes see major improvements in comfort and absorption.
Train Smart. Fuel Smarter.
The XACT Carb Calculator isn’t about gimmicks or guesswork. It’s about giving you the science-backed, real-world advice you need to perform at your best.
Here’s what you’ll learn:
- Exactly how many carbs/hour you need for your session
- Which form of carbs suits your activity best
- Whether your gut needs training (and how to do it)
Try the XACT Carb Calculator now — and get ready to fuel every effort with purpose.
References
- Martinez IG et al. The Effect of Gut-Training and Feeding-Challenge on Markers of Gastrointestinal Status in Response to Endurance Exercise. Sports Med. 2023.
- Jeukendrup AE. Training the Gut for Athletes. Curr Sports Med Rep. 2017.
- Hearris MA et al. Effects of Carbohydrate Form on Exogenous Oxidation and Performance. J Appl Physiol. 2022.
- Cox GR et al. Daily Training with High Carbohydrate Availability Increases Exogenous Carbohydrate Oxidation. J Appl Physiol. 2010.