Maurten Energy Calculator

Race Distance

Estimated Race Time

Elevation Gain (m) More elevation increases effort and carbohydrate needs.

Body Weight (kg)

Caffeine Preference

Fueling Ambition (Carbs/h) Your body uses carbohydrates as primary fuel at intensity. Higher intake helps preserve muscle glycogen and maintain pace towards the end.

Training the Gut

Research confirms that the gut is highly adaptable [5, 6]. Practicing your fueling strategy during training can:

Improve Absorption: Teach your body to absorb more carbohydrates by upregulating transporters [1, 5, 6].
Reduce Discomfort: Significantly decrease bloating and cramping on race day [7].

Tip: Simulate race-intensity fueling in your weekly long runs to condition your digestive system.

I will carry a bottle of Drink Mix

Drink Mix 320 delivers high levels of energy (80g carbs) and hydration. Recommended if you can carry a bottle or access it at special stations.

Steps to Success

Why we recommend Maurten

Hydrogel Technology: Maurten binds carbohydrates into a hydrogel in the stomach, allowing them to move more quickly into the intestine → faster absorption with less GI distress.

Very Low Additives: No colorants, no preservatives, no artificial flavors. Many competing gels use sweeteners and acids that irritate the stomach.

High Carbohydrate Density: 25–80 g per serving — among the highest on the market while still being digestible.

Disclaimer: The recommendations provided by this calculator are based on general sports nutrition guidelines and scientific research. Individual needs may vary.

References:

Carbohydrate Needs During Endurance Exercise (60–90g/h):

Jeukendrup, A. E. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(S1), 25–33.
Jeukendrup, A. E. & Moseley, L. (2010). Multiple transportable carbohydrates enhance gastric emptying and fluid delivery. Journal of Applied Physiology, 108(2), 550–555.
Cermak, N. M. & van Loon, L. J. (2013). The use of carbohydrates during exercise as an ergogenic aid. Sports Medicine, 43(11), 1139–1155.
Stellingwerff, T. & Cox, G. R. (2014). Systematic review: Nutrition for endurance sports – Marathon, triathlon, road cycling. Journal of Sports Sciences, 32(1), 12–18.

GI Absorption Capacity & Training Adaptations:

Rowlands, D. S. et al. (2015). Optimizing carbohydrate composition and intake during prolonged endurance exercise. Current Opinion in Clinical Nutrition & Metabolic Care, 18(6), 581–588.
Cox, G. R. et al. (2010). Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. Journal of Applied Physiology, 109(1), 126–134.
de Oliveira, E. P., Burini, R. C., & Jeukendrup, A. (2014). Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports Medicine, 44(S1), 79-85.

Caffeine Use in Endurance Performance (3–6mg/kg):

Spriet, L. L. (2014). Exercise and sport performance with low doses of caffeine. Sports Medicine, 44(S2), 175–184.
Ganio, M. S. et al. (2009). Evidence-based approach to the ergogenic effects of caffeine in endurance athletes. International Journal of Sport Nutrition and Exercise Metabolism, 19(3), 225–242.
Burke, L. M. (2008). Caffeine and sports performance. Applied Physiology, Nutrition, and Metabolism, 33(6), 1319–1334.

Glycogen Use & Marathon Fueling Strategies:

Romijn, J. A. et al. (1993). Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity and duration. American Journal of Physiology, 265(3), E380–E391.
Beis, L. Y. et al. (2012). Chronic hydration status and marathon performance. Journal of Strength and Conditioning Research, 26(3), 798–806.
Smith, J. W. et al. (2013). Optimized carbohydrate intake during endurance exercise improves performance. Journal of Sports Sciences, 31(13), 1468–1476.