Daily Carb Intake Calculator: How Many Carbs Should You Eat Per Day?

Estimate adult carbohydrate reference ranges from your age, sex input, height, weight, and selected activity level. The calculation runs in your browser without AI. It uses an estimated calorie scenario and population reference range—it does not set a personal carbohydrate target or predict weight change.

Method & evidence

How these carbohydrate ranges are calculated

The calculator creates calorie scenarios from a resting-energy equation and a selected activity factor, then converts 45%, 55%, and 65% of those calories into carbohydrate grams. These are adult population reference points—not a meal plan, a diagnosis, or a prediction of weight change.

01 · ENERGY

Estimate resting energy

Use age, sex input, height, and weight in the Mifflin–St Jeor equation.

02 · SCENARIOS

Apply an activity factor

Multiply by the selected factor, then show maintenance and fixed calorie-adjustment scenarios.

03 · CARBOHYDRATE

Convert calories to grams

Calculate 45%, 55%, and 65% of each scenario, then divide by 4 kcal per gram.

A calorie scenario is not a recommended rate of weight change.

The rows use fixed daily adjustments of −500, −1,000, +500, and +1,000 kcal. They are arithmetic illustrations only. They do not account for changing energy needs, health conditions, medication, pregnancy, breastfeeding, or individual nutrition requirements.

What reference range does the tool use?

The Dietary Reference Intakes list an Acceptable Macronutrient Distribution Range (AMDR) of 45–65% of energy from carbohydrate for adults. This tool shows the lower end, midpoint, and upper end of that range: carbohydrate grams/day = estimated calories × 0.45, 0.55, or 0.65 ÷ 4. [1]

An AMDR is a population reference range. It is not a carbohydrate target for a specific sport, health condition, medication, or eating pattern. The adult carbohydrate RDA of 130 g/day answers a different question and is not treated here as a personal floor. [2]

Where do the calorie scenarios come from?

Resting kcal/day = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + coefficient. The coefficient is +5 for the male equation and −161 for the female equation. The tool multiplies that result by its selected activity factor: 1.2, 1.375, 1.465, 1.55, 1.725, or 1.9.

Mifflin and colleagues derived the resting-energy equation using indirect calorimetry in 498 healthy adults aged 19–78. The study supports the resting-energy equation—not the activity factors, the calorie adjustments, or a personal carbohydrate target. [3]

For a 2,000 kcal/day maintenance scenario, the displayed range is 225–325 g/day: 2,000 × 0.45 ÷ 4 = 225 g and 2,000 × 0.65 ÷ 4 = 325 g. The 55% reference is 275 g/day.

What does this calculation leave out?

The result does not distinguish fibre, added sugars, food quality, meal timing, or the different effects of particular carbohydrate-rich foods. Nor does it measure blood glucose or account for diabetes treatment, gastrointestinal conditions, or other clinical needs.

This is a general adult calculator. Children, adolescents, pregnancy, breastfeeding, people managing medical conditions, and anyone with a history of disordered eating should seek individualized guidance rather than use a generic calorie-adjustment row. The calculation runs locally without AI, and the displayed result is not automatically saved to Shelog.

References & what they support

  1. Health Canada. Dietary Reference Intakes: Reference Values for Macronutrients.

    Official DRI overview and AMDR reference; it does not set a personal carbohydrate target.

  2. National Academies. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements.

    Supports the adult carbohydrate AMDR of 45–65% and adult RDA of 130 g/day; it does not validate this calculator's calorie scenarios.

  3. Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51:241–247.

    Source of the resting-energy equation, not activity multipliers, calorie scenarios, or carbohydrate targets.

Disclaimer: This tool provides estimates only and is not a substitute for professional dietary advice. Always consult a nutritionist or healthcare provider for personalized guidance.