Weight loss calculators
Free, simple tools to understand your numbers: BMI, daily calories, calorie deficit, protein and water.
- BMI calculator Your body mass index, category and healthy weight range, using the CDC's formula. Open calculator
- TDEE calculator How many calories you burn in a day, your maintenance calories, from your age, size and activity level. Open calculator
- Calorie deficit calculator How many calories to eat a day to lose 1 or 2 pounds a week, and about how long your goal weight takes. Open calculator
- Protein calculator How much protein you need a day and at each meal, for weight loss, maintenance or building muscle. Open calculator
- Water intake calculator How much water to drink a day, in ounces, cups and liters, based on your weight and how active you are. Open calculator
- Ready to talk to a clinician? Answer a few questions about your health. A licensed clinician reviews your intake, and you're only charged if treatment is prescribed. See if I qualify
Simple calculators for weight loss
These free calculators answer the first questions most people have about their weight, each in under a minute. No account, no email.
- The BMI calculator shows your body mass index, its category and the healthy weight range for your height, using the CDC's formula.
- The TDEE calculator shows how many calories you burn in a day, your maintenance calories, using the Mifflin-St Jeor equation and your activity level.
- The calorie deficit calculator shows how many calories to eat a day to lose 1 or 2 pounds a week, and about how long your goal weight takes.
- The protein calculator shows how much protein you need a day and at each meal, for weight loss, maintenance or building muscle.
- The water intake calculator shows how much to drink a day, in ounces, cups and liters, based on your weight and activity.
Each page also explains the number in plain language: how it's calculated, what it means, and how to use it if you're taking a GLP-1 medication like semaglutide or tirzepatide.
Sources
4 references
- Centers for Disease Control and Prevention. Adult BMI categories.
- Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51:241–247.
- Leidy HJ, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101:1320S–1329S.
- Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. 2005.
Calculator questions,
answered
What people ask us most about these tools.
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Yes. Every calculator is free to use, and you don't need an account. Each one takes under a minute.
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Start with the BMI calculator to see where your weight sits for your height. Then use the TDEE calculator to see how many calories you burn in a day, and the calorie deficit calculator to see how many to eat to lose weight. The protein and water intake calculators cover two more daily targets: how much protein to eat and how much to drink.
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BMI compares your weight with your height and puts it in a category, like healthy weight or overweight. TDEE is the number of calories you burn in a day. A calorie deficit is eating less than that, which is how weight loss happens.
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It can show whether your BMI is in the range these medications are prescribed for: generally 30 or higher, or 27 or higher with a weight-related condition. A licensed clinician reviews your health history and decides.
Keep reading
Articles from our team on BMI, weight loss and nutrition.
How to Qualify for GLP-1 Medications: BMI, Health, and Eligibility Explained
Are you eligible for weight loss medication? Read our guide on 2026 BMI requirements, health conditions, and how to qualify for GLP-1 treatment online.
Protein on GLP-1s: How Much You Really Need and Easy Ways to Hit It
Learn exactly how much protein you need on GLP-1 medications to preserve lean muscle mass. Discover practical, nausea-friendly tips to hit your goals.
A 7-Day GLP-1 Meal Plan: High-Protein, Low-Volume, and Nausea-Friendly
Struggling to eat on GLP-1s? This 7-day high-protein, nausea-friendly meal plan is built around your new metabolism.
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