# How many carbs should I eat a day? Finds grams of carbohydrate a day from your daily calories and a carb share, with the 45% to 65% range the Dietary Guidelines give for adults, grams per meal, and the 130 g RDA. - Page: https://www.acalculator.org/health/carb-calculator - JSON spec: https://www.acalculator.org/health/carb-calculator.json - Version: 774502710de9 ## Default answer Example with the default inputs (Calories a day 2,000, Calories from carbs 50%, Meals and snacks a day 3): Eat about 250 g of carbs a day (within the 45% to 65% range). ## Inputs | Key | Label | Description | | --- | --- | --- | | cal | Calories a day | The calories you eat, or plan to eat, each day. | | pct | Calories from carbs | The share of your calories that comes from carbohydrate; adults are advised 45% to 65%. | | meals | Meals and snacks a day | How many times a day you eat, to split the carbs evenly. | ## Outputs | Key | Label | Description | | --- | --- | --- | | carbs | Carbs a day | Calories × share ÷ 100 ÷ 4 calories per gram. | | low | At 45% of calories | The low end of the adult AMDR range. | | high | At 65% of calories | The high end of the adult AMDR range. | | perMeal | Carbs per meal | Carbs a day ÷ meals and snacks. | | kcal | Calories from carbs | Calories × share ÷ 100. | | range | Compared with 45% to 65% | Whether the share is below, within, or above the adult AMDR range. | | rda | Compared with the 130 g RDA | Whether carbs a day reach the RDA of 130 g. | ## Method carbs (g) = calories × share ÷ 100 ÷ 4; at 45% and 65% for the AMDR range; per meal = carbs ÷ meals. The RDA is 130 g a day. ## Assumptions - Carbohydrate gives 4 calories per gram (the general factor in US nutrition labels). - The 45% to 65% range (AMDR) and the 130 g RDA are for healthy adults and children 1 year and older; pregnancy and breastfeeding have higher RDAs, and a doctor or dietitian may advise otherwise. - The page does not estimate calories; type your own figure. ## Worked examples 1. cal = 2,000, pct = 50%, meals = 3 gives carbs = 0.25, low = 0.225, high = 0.325, perMeal = 0.083333, kcal = 1,000, range = within the 45% to 65% range. Source: Slavin J, Carlson J. Carbohydrates. Advances in Nutrition 2014;5(6):760-761 (IOM RDA for carbohydrate 130 g/d; AMDR 45–65% of total calories), https://pmc.ncbi.nlm.nih.gov/articles/PMC4224210/ (retrieved 2026-10-02); U.S. Department of Agriculture and U.S. Department of Health and Human Services, Dietary Guidelines for Americans, 2020-2025, Appendix 1 (carbohydrate: RDA 130 g a day; AMDR 45% to 65% of calories for adults), https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf; 21 CFR 101.9(c)(1)(i)(C) (4 calories per gram of carbohydrate), https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9. 2. cal = 1,800, pct = 20%, meals = 3 gives carbs = 0.09, range = below the 45% to 65% range (low carb), rda = 40 g below 130 g. Source: U.S. Department of Agriculture and U.S. Department of Health and Human Services, Dietary Guidelines for Americans, 2020-2025, Appendix 1 (carbohydrate: RDA 130 g a day; AMDR 45% to 65% of calories for adults), https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf; 21 CFR 101.9(c)(1)(i)(C) (4 calories per gram of carbohydrate), https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9. 3. cal = 2,600, pct = 60%, meals = 4 gives carbs = 0.39, perMeal = 0.0975, high = 0.4225, rda = at or above 130 g. Source: U.S. Department of Agriculture and U.S. Department of Health and Human Services, Dietary Guidelines for Americans, 2020-2025, Appendix 1 (carbohydrate: RDA 130 g a day; AMDR 45% to 65% of calories for adults), https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf; 21 CFR 101.9(c)(1)(i)(C) (4 calories per gram of carbohydrate), https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9. ## FAQ ### How many carbs should I eat a day? The Dietary Guidelines for Americans give adults a range of 45% to 65% of calories from carbohydrate. On 2,000 calories a day, that is 2,000 × 0.45 ÷ 4 = 225 g to 2,000 × 0.65 ÷ 4 = 325 g of carbs. ### How do I turn a carb percentage into grams? Multiply your calories by the percentage, then divide by 4, because a gram of carbohydrate gives 4 calories. 50% of 2,000 calories is 1,000 calories, or 1,000 ÷ 4 = 250 g. ### What is the RDA for carbohydrate? 130 g a day for adults and children 1 year and older, set by the Institute of Medicine as the amount of glucose the brain needs. Pregnancy and breastfeeding have higher RDAs. Most people eat well above it. ### How many carbs are low carb? There is no single official cut-off. A share below 45% of calories is below the AMDR range, and the page labels it low carb. At 20% of 1,800 calories, carbs are 90 g a day, 40 g below the RDA. Talk to a doctor or dietitian before a very low-carb diet. ### How many carbs per meal? Divide carbs a day by how many times you eat. 250 g over 3 meals is about 83 g a meal; 390 g over 4 meals and snacks is 97.5 g each. ### Where do my daily calories come from? Type the calories you eat or plan to eat. If you do not know them, a TDEE or calorie calculator estimates them from your body and activity, and the macro calculator splits them into protein, carbs and fat. ## Sources - U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025, Appendix 1 (carbohydrate: RDA 130 g a day; AMDR 45% to 65% of calories for adults). https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf - Slavin J, Carlson J. Carbohydrates. Advances in Nutrition. 2014;5(6):760-761 (the IOM RDA for carbohydrate is 130 g/d for adults and children aged 1 year and older; the AMDR is 45–65% of total calories). https://pmc.ncbi.nlm.nih.gov/articles/PMC4224210/ (retrieved 2026-10-02) - Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press; 2005. https://www.nationalacademies.org/publications/10490 - U.S. Code of Federal Regulations, 21 CFR 101.9(c)(1)(i)(C): general factor of 4 calories per gram for total carbohydrate. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9