Quick answer: On 2,000 kcal a day with half from carbohydrate, you eat 2,000 × 50% ÷ 4 = 250 g of carbs; the recommended 45–65% range is 225 to 325 g.
How it's calculated
Carbohydrate grams = daily calories × share ÷ 4, because each gram of carbohydrate gives about 4 kcal (the general Atwater factor). Some calculators use 3.75 kcal per gram, the factor for carbohydrate counted as simple sugars, which gives about 7% more grams for the same calories. The National Academies set the acceptable range for adults at 45–65% of calories and the RDA at 130 g a day, the glucose the brain uses.
Fibre is part of carbohydrate; the adequate intake is 14 g for every 1,000 kcal, or 28 g on 2,000 kcal. Added sugars should stay under 10% of calories (WHO and the US Dietary Guidelines).
The grams depend on the calorie number you start from, so estimate that first with the calorie calculator. The figure says nothing about carbohydrate quality, and people with diabetes often need an individual carbohydrate plan from their care team.
Worked examples
- 2,000 kcal at 50%: 2000 × 0.50 ÷ 4 = 250 g
- 2,500 kcal at 55%: 2500 × 0.55 ÷ 4 = 343.75 g
- 1,800 kcal, 45–65% range: 202.5 – 292.5 g
Frequently asked questions
How many carbs should I eat a day?
For most adults, 45–65% of calories: about 225–325 g on a 2,000 kcal diet. Very active people often need more.
What counts as low carb?
There is no single definition; under 130 g a day (below the RDA) is often called low carbohydrate, and under about 50 g very low.
Do grams include fibre?
Yes. Total carbohydrate includes fibre and sugars. Some labels show net carbs, which subtract fibre.
How do I count carbs from a food label?
Find the total carbohydrate per serving and multiply it by the servings you actually eat. Check the serving size, because a packet often holds more than one.
Are all carbohydrates the same?
No. Whole grains, legumes, fruit and vegetables also bring fibre and nutrients. WHO advises keeping free sugars under 10% of your calories.
Can I use this if I have diabetes?
The arithmetic is the same, but the right carbohydrate amount depends on your treatment, so agree a target with your doctor or dietitian.