How many grams of carbs should I eat per day?

It depends on your calorie target and goals. The IOM AMDR is 45–65% of calories. Endurance athletes often go higher; people on low-carb or keto plans go lower. This tool lets you pick any % from 5–65 and shows the gram total.

Why divide kcal by 4 to get grams?

Carbohydrate provides about 4 kilocalories per gram (Atwater factor). So if you allocate 1,000 kcal to carbs, that is 250 g.

Is a low-carb diet safe?

For most healthy adults short-term low-carb eating is well tolerated, but ketogenic-range intakes (under 50 g/day) can affect medication needs for people with diabetes or on blood pressure drugs. Talk to a clinician before making big changes.

Does this calculator distinguish fiber from net carbs?

No. It calculates total carbohydrate grams. If you want to track net carbs (total − fiber) subtract your daily fiber grams from the tool's output.

Does this tool store my data?

No. Inputs stay in your browser and are cleared when you close the tab.

Is the carb calculator free?

Yes — completely free, no signup or limits.

Carb Calculator

Calculate daily carbohydrate grams from calorie total and target carb percentage.

Written by Golam Rabbani, Founder & Lead Engineer — Last updated 2026-05-01

This interactive tool requires JavaScript. Read the formula and worked example below; you can compute the result by hand.

How to use this carb calculator

Enter your total daily calorie target.
Drag the slider to set your target carbohydrate percentage (5–65%).
Watch the AMDR note update so you know whether the chosen % is inside the IOM guideline range.
Press Calculate to see daily carbs in grams and the kcal contribution.

About this carb calculator

The carb calculator converts a daily calorie target into grams of carbohydrate at the percentage you choose. It uses the Atwater factor of 4 kcal per gram of carbohydrate, so the grams shown always reconcile with the kcal portion of your daily intake. The slider spans 5% to 65% so it covers everything from very-low-carb / ketogenic plans through to high-carb endurance fueling.

The recommended bands are based on the Institute of Medicine's Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates, which is 45–65% of daily calories for adults (Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, IOM 2002/2005). Below 45% the tool flags you as outside the AMDR and above 65% as above. This is an estimate for informational purposes and is not a substitute for advice from a registered dietitian or qualified clinician.

For example, on 2,000 kcal/day at 50% carbs: carbs = 2,000 × 0.50 / 4 = 250 g/day, contributing 1,000 kcal from carbohydrate. The tool is useful for setting a daily carb floor or ceiling, comparing how a low-carb 25% plan stacks up against a 50% Balanced plan at the same calories, and translating a coach's percentage prescription into a number you can track.

FAQ

How many grams of carbs should I eat per day?: It depends on your calorie target and goals. The IOM AMDR is 45–65% of calories. Endurance athletes often go higher; people on low-carb or keto plans go lower. This tool lets you pick any % from 5–65 and shows the gram total.
Why divide kcal by 4 to get grams?: Carbohydrate provides about 4 kilocalories per gram (Atwater factor). So if you allocate 1,000 kcal to carbs, that is 250 g.
Is a low-carb diet safe?: For most healthy adults short-term low-carb eating is well tolerated, but ketogenic-range intakes (under 50 g/day) can affect medication needs for people with diabetes or on blood pressure drugs. Talk to a clinician before making big changes.
Does this calculator distinguish fiber from net carbs?: No. It calculates total carbohydrate grams. If you want to track net carbs (total − fiber) subtract your daily fiber grams from the tool's output.
Does this tool store my data?: No. Inputs stay in your browser and are cleared when you close the tab.
Is the carb calculator free?: Yes — completely free, no signup or limits.