This carbohydrate calculator estimates how many grams of carbs you should eat each day. It works out your daily calorie needs from your age, size, activity and goal, then applies the recommended range of 45–65% of calories from carbohydrate, with fiber and sugar targets too.
How daily carbs are calculated
- Basal metabolic rate (BMR) with the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women.
- Daily calories = BMR × activity factor, adjusted for your goal.
- Carbs in grams = calories × percentage ÷ 4, because each gram of carbohydrate provides 4 kcal.
Carbohydrate guidelines
| Guideline | Amount |
|---|---|
| Acceptable range (adults) | 45–65% of daily calories |
| Recommended minimum (RDA) | 130 g per day |
| Fiber | About 14 g per 1,000 kcal |
| Free or added sugars | Less than 10% of calories |
The 45–65% range and the 130 g minimum come from the US National Academies’ Dietary Reference Intakes. The sugar limit follows World Health Organization guidance.
Worked example
A 35-year-old moderately active woman who weighs 65 kg and is 165 cm tall needs about 2,085 kcal a day to maintain her weight. That works out to 235–339 g of carbohydrate a day, with about 29 g of fiber.
Choosing better carbs
- Favor whole grains, beans, lentils, vegetables and whole fruit, which bring fiber, vitamins and minerals.
- Limit sugary drinks, sweets and refined grains.
- Spread carbs through the day and pair them with protein if you want steadier energy.
Frequently asked questions
How many carbs should I eat a day?
Most adults are advised to get 45–65% of their calories from carbohydrate. On a 2,000 kcal diet that is about 225–325 g a day.
How many carbs are in a low-carb diet?
There is no single definition. Many low-carb diets use under 130 g a day, or under about 26% of calories; very low-carb or ketogenic diets often use 20–50 g.
Should I count total carbs or net carbs?
Nutrition labels in the US list total carbohydrate, which includes fiber. Net carbs subtract fiber, but the term is not officially defined. Guidelines here use total carbohydrate.
Do I need fewer carbs to lose weight?
Weight loss depends mainly on total calories. Lower-carb and higher-carb diets can both work if they create a calorie deficit you can keep up.
Is this suitable if I have diabetes?
Use it only as a general guide. People with diabetes should follow the carbohydrate targets agreed with their doctor or dietitian.
Related calculators
Sources
- National Academies: Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids
- World Health Organization: Guideline on sugars intake
Last reviewed: October 2026. This calculator is for information only and does not replace advice from a doctor or other qualified health professional.