Carbohydrate Calculator
Compute the daily grams of carbohydrate you should eat given your total calorie target and the share of calories that should come from carbs.
Last updated: September 2026
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About this calculator
Carbohydrates provide 4 kcal per gram, so daily carb grams = (daily calories × carb%) / 4. The USDA Dietary Guidelines and the Institute of Medicine (now National Academies) recommend that 45–65% of calories come from carbohydrates in the 'Acceptable Macronutrient Distribution Range' (AMDR).
Popular alternatives to the 45–65% range include lower-carb (30–40%) and ketogenic (5–10%) diets, both of which have strong adherents and specific medical indications (ketogenic diet for epilepsy, low-carb trials for type 2 diabetes management). No single ratio fits everyone; the RDA minimum for carbohydrates is 130 g/day, based on the brain's baseline glucose need, and going below that requires ketone adaptation.
Endurance athletes at the other extreme benefit from higher intake (55–70% of calories, up to 8–10 g/kg body weight during heavy training). The right ratio depends on activity level, metabolic health, personal preference, and medical context. Consult a registered dietitian for individualized advice.
How to use
Example — a 2 000 kcal/day standard-mix target. Enter calorieIntake = 2000, carbPercent = 50. Result = (2000 × 0.50) / 4 = 1000 / 4 = 250 g of carbs per day. That is the midpoint of the AMDR range and matches the USDA's default 2 000-calorie reference diet on nutrition labels. Example — a lower-carb approach. Same 2 000 kcal target, carbPercent = 30. Result = (2000 × 0.30) / 4 = 600 / 4 = 150 g. Still above the RDA minimum of 130 g, but leaves room for higher protein (see /en/calculators/nutrition/protein-intake-calculator/) or higher fat (see /en/calculators/nutrition/fat-intake-calculator/) to make up the calorie budget.
Frequently asked questions
What is the RDA for carbs?
The Recommended Dietary Allowance (RDA) for carbohydrates is 130 g/day for adults, based on the brain's baseline glucose requirement plus a margin of safety. This is the minimum, not the recommended intake — the Acceptable Macronutrient Distribution Range (AMDR) is 45–65% of calories, which for a 2 000-calorie diet is 225–325 g of carbs.
Are all carbs equal?
No. Complex carbs (whole grains, legumes, vegetables) come with fibre, vitamins, and minerals and produce a slower blood-sugar response. Refined carbs (white flour, sugar, most sugary drinks) provide 'empty calories' with rapid glucose spikes. Aim for most of your daily carb intake to come from whole-food sources; the fibre calculator at /en/calculators/nutrition/fiber-intake-calculator/ helps track that.
What about ketogenic and low-carb diets?
Ketogenic diets restrict carbs to roughly 5% of calories (20–50 g/day), forcing the body into ketosis where fat is the primary fuel. Low-carb diets (30–40%, 100–150 g) still allow fruit and legumes and are easier to sustain long-term. Both have strong research support for specific conditions (weight loss, type 2 diabetes management, epilepsy) but require careful planning and, for keto, some initial adjustment (the 'keto flu').
Do endurance athletes need more?
Yes. During intense endurance training, muscles rely on glycogen (stored carbohydrate) for the highest-effort work. Guidelines for endurance athletes range from 5–7 g/kg body weight for moderate training up to 8–12 g/kg for heavy training days. A 70 kg athlete on a heavy-training day might target 700+ g of carbs — far above the sedentary 250 g standard.