Carb cycling calculator
Carb fasting keeps carbohydrate near zero on fast days and normal on the rest. This estimates your daily energy need, then gives a starting carbohydrate range for normal days — a place to begin, not a rule to obey.
Resting energy
1763 kcal
Daily need
2424 kcal
Normal-day carbs
210–275 g
On fast days, keep carbohydrate near zero (under ~30 g). On normal days, aim for roughly 210–275 g of mostly whole-food carbs.
A starting estimate, not medical or nutrition advice. Energy needs vary person to person — adjust based on how you feel and respond, and talk to a clinician or dietitian if you have a medical condition.
How it's calculated
Resting energy uses the Mifflin-St Jeor equation, the dietitian-standard estimate of resting metabolic rate:
- Men: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
We multiply that by an activity factor for your daily need, then take a moderate share of those calories as carbohydrate (÷ 4 kcal/g) for the normal-day range. Fast days stay near zero by design.
Worked example: a lightly active man, 82 kg / 178 cm / 35 y → resting energy ≈ 1,763 kcal, daily need ≈ 2,424 kcal. At ~35–45% carbohydrate, that's roughly 210–275 g on a normal day — and near zero on a fast day.
What to do with the number
Treat it as a starting point and adjust by how you feel and respond. The exact gram count matters far less than the pattern: fast days vs normal days. For meal ideas, see the carb cycling meal plan, and to lay out your week, use the fast-day planner.