Carbohydrate is the body’s main fuel, especially for the brain and for hard exercise. The recommended dietary allowance of 130 g a day covers the brain’s glucose needs; endurance athletes may need 6–10 g per kg of body weight.
How to use the Carb Calculator
- Sex
- Age
- Weight
- Height
- Activity level
- Goal
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter your details and activity level, or your known calorie target. The calculator estimates daily energy needs and converts the recommended percentages to grams.
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Age | In years |
| Weight | Units: kg, lb, st, g |
| Height | Units: cm, in, m, ft, mm |
| Activity level | Choose one: Basal metabolic rate (no activity), Sedentary – little or no exercise, Light – exercise 1–3 times a week, Moderate – exercise 4–5 times a week … |
| Goal | Choose one: Maintain, Lose 0.5 kg a week, Gain 0.25 kg a week |
What each result means
- Carbs at 40% of calories = [Daily calories]×0.40÷4
- Carbs at 45% (guideline minimum) = [Daily calories]×0.45÷4
- Carbs at 55% (middle of the range) = [Daily calories]×0.55÷4
- Carbs at 65% (guideline maximum) = [Daily calories]×0.65÷4
- Carbs at 75% (endurance training) = [Daily calories]×0.75÷4
Example values
How the main result changes when Age changes and everything else stays at the example values above:
| Age (years) | Carbs at 55% (middle of the range) (g/day) |
|---|---|
| 15 | 361 |
| 22.5 | 354 |
| 30 | 346 |
| 37.5 | 338 |
| 45 | 331 |
| 60 | 316 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Carbs g = calories × % ÷ 4
Guideline range: 45–65% of calories
Minimum RDA: 130 g/day for adults
Worked example
Inputs — Sex: Male; Age: 30 years; Weight: 75 kg; Height: 178 cm; Activity level: Moderate – exercise 4–5 times a week; Goal: Maintain.
Results — Daily calories = 2,516 kcal/day; Carbs at 40% of calories = 252 g/day; Carbs at 45% (guideline minimum) = 283 g/day; Carbs at 55% (middle of the range) = 346 g/day; Carbs at 65% (guideline maximum) = 409 g/day; Carbs at 75% (endurance training) = 472 g/day.
Key terms
- RDA
- Recommended dietary allowance.
Frequently asked questions
How many carbs should I eat to lose weight?
Total calories matter most; many people find 100–150 g a day easier to manage.
What are good carbohydrate sources?
Whole grains, legumes, vegetables, fruit and dairy.
How much sugar is too much?
Keep added sugars below 10% of calories, ideally lower.