Calories and Carbs Calculator

How the number is made

kcal ≈ average watts × hours × 3.6. Watts × hours × 3.6 is the work in kilojoules; the rule counts each kJ of pedal work as about 1 kcal of food, which hides metabolic efficiency inside the constant. Carbs g/h = watts × 0.3, clamped to 30–120. Example: 200 W for 3 h → 2160 kcal and 60 g/h.

One mechanical kilojoule equals one food kilocalorie only at about 24% gross efficiency (1 kcal = 4.184 kJ). Many riders sit nearer 20–23%, so the real burn can be up to about 20% higher. Use average power with coasting counted, not normalised power, which runs higher. Watts × 0.3 g/h covers about a third of the kilocalories burned each hour with carbohydrate (4 kcal per gram), clamped to 30–120 g/h. Glucose alone is absorbed at only about 60 g/h, so higher targets need a glucose–fructose mix. Gut tolerance, heat and drink mix still change what you can take in.

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