Introduction
The Carb Calculator helps you figure out how many carbohydrates you should eat each day. Carbs are one of the three main nutrients your body uses for energy, along with protein and fat. The right amount of carbs depends on things like your age, weight, activity level, and health goals. Whether you want to lose weight, build muscle, or just eat a balanced diet, knowing your daily carb needs is a good place to start. This tool takes your personal details and gives you a carb target in grams that fits your lifestyle. Use it alongside our Macro Calculator to make smarter food choices and take control of your nutrition.
How to Use Our Carb Calculator
Enter your body details, activity level, and diet preferences below. The calculator will tell you how many grams of carbs, protein, and fat you should eat each day based on your goals.
Unit System: Pick either US (Imperial) or Metric to set how your height and weight will be measured.
Age: Enter your current age in years. The calculator accepts ages between 15 and 80.
Sex: Select Male or Female. This helps estimate how many calories your body burns at rest. If you use the Katch-McArdle formula, this field is not needed.
Height: Enter your height in feet and inches if using Imperial, or in centimeters if using Metric.
Weight: Enter your current body weight in pounds (Imperial) or kilograms (Metric). If you're unsure about your ideal target, try our Ideal Body Weight Calculator for a reference point.
Activity Level: Choose the option that best matches how often and how hard you exercise each week. Options range from Sedentary (little or no exercise) to Extra Active (very intense daily exercise). Click the "Activity Level Definitions" link for a full description of each level.
Goal: Select your weight goal. You can choose to lose weight, maintain your current weight, or gain weight. Each option adds or subtracts a set number of calories per day from your total.
BMR Formula: Choose which formula the calculator uses to estimate your base calorie burn. Mifflin-St Jeor is the default and works for most people. Katch-McArdle is more accurate if you know your body fat percentage.
Body Fat %: This field only appears when you select the Katch-McArdle formula. Enter your estimated body fat percentage, between 3% and 60%. You can use our Lean Body Weight Calculator to help estimate your lean mass and body fat.
Carbs (% of Calories): Use the slider to set what portion of your daily calories should come from carbohydrates. You can choose anywhere from 10% to 70%.
Protein (% of Calories): Use the slider to set what portion of your daily calories should come from protein. You can choose anywhere from 10% to 60%. For a more detailed look at your protein needs, check out our Protein Calculator.
Fat (% of Calories): This value is calculated automatically. It fills in whatever percentage is left after your carb and protein choices. The combined total of carbs and protein must not go above 90%.
Once you have filled in all fields, click Calculate Carbs to see your results. You will get your daily carb, protein, and fat targets in grams, your total target calories, your BMR (basal metabolic rate), and your TDEE (total daily energy expenditure). The results also include a macronutrient breakdown chart, a detailed table, a suggested per-meal carb split, and a comparison of carb intake across all activity levels. Click Reset at any time to return all fields to their default values.
What Are Carbohydrates and Why Do They Matter?
Carbohydrates are one of the three main macronutrients your body needs, along with protein and fat. They are your body's favorite source of energy. When you eat carbs, your body breaks them down into glucose (blood sugar), which fuels your brain, muscles, and organs throughout the day.
Not all carbs are the same. Simple carbohydrates — found in sugar, candy, and white bread — break down quickly and can cause sharp spikes in blood sugar. Complex carbohydrates — found in whole grains, vegetables, beans, and oats — break down slowly and give you steady, long-lasting energy. Most nutrition experts recommend getting the majority of your carbs from complex sources. Complex carbs are also typically higher in fiber, which supports digestive health and helps you feel full longer.
How Many Carbs Should You Eat Per Day?
There is no single answer that works for everyone. The right amount of daily carbs depends on your age, sex, height, weight, how active you are, and what your goals are. Someone who exercises hard every day needs more carbs than someone who sits at a desk most of the time. A person trying to lose weight may benefit from eating fewer carbs, while someone trying to build muscle or gain weight may need more.
General dietary guidelines suggest that carbohydrates should make up about 45% to 65% of your total daily calories. For a person eating 2,000 calories per day, that works out to roughly 225 to 325 grams of carbs. However, many popular diets adjust this range — low-carb diets may drop it to 10–30%, while high-performance athletes sometimes go above 60%.
How This Calculator Works
This carb calculator first estimates your Basal Metabolic Rate (BMR) — the number of calories your body burns at rest just to stay alive. It offers two well-known formulas for this. The Mifflin-St Jeor equation uses your age, sex, height, and weight. The Katch-McArdle formula uses your lean body mass, which requires knowing your body fat percentage, and can be more accurate for people who know that number.
Next, the calculator multiplies your BMR by an activity factor to find your Total Daily Energy Expenditure (TDEE) — the total calories you burn in a day including exercise and movement. It then adjusts that number based on your goal (lose weight, maintain, or gain weight). Finally, it splits your target calories into carbs, protein, and fat based on the percentages you choose, and converts those calories into grams. Carbohydrates and protein each have 4 calories per gram, while fat has 9 calories per gram.
Tips for Choosing the Right Carb Intake
- For weight loss: Many people see results by setting carbs between 30–45% of calories and keeping protein higher to help preserve muscle.
- For maintenance: A balanced split around 45–55% carbs works well for most moderately active adults.
- For athletic performance: Endurance athletes and people with very active lifestyles often need 55–65% or more of their calories from carbs to fuel training. Runners can pair their carb planning with a Running Pace Calculator or Marathon Pace Calculator to dial in their nutrition around training sessions.
- For low-carb or keto diets: These typically keep carbs at 10–25% of total calories. This approach is not right for everyone and should be discussed with a healthcare provider.
Keep in mind that the quality of your carbs matters just as much as the quantity. Focus on whole foods like fruits, vegetables, legumes, and whole grains rather than processed snacks and sugary drinks. Staying properly hydrated is also essential — use our Water Intake Calculator to find out how much water you should be drinking each day. Also remember that these calculations provide estimates — individual needs can vary. Metrics like your waist-to-hip ratio or VO2 max can give you additional insight into your overall health and fitness. If you have diabetes, kidney disease, or other health conditions, talk to a doctor or registered dietitian before making big changes to your carb intake.