Weight Loss & BMI Calculator

Get a rough, personalized estimate of your BMI and a weekly weight trend based on your activity level and how much you eat. Enter your numbers below — nothing you type is stored or sent anywhere.

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A rough daily average is fine. This is what lets us estimate whether you are likely to gain, lose, or maintain.

This tool gives a rough estimate only, not a medical or nutrition recommendation. Everyone's metabolism is different, so talk with a doctor or registered dietitian before starting a new weight-loss or weight-gain plan.


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How this calculator works

We calculate your Body Mass Index (BMI) from your height and weight, then estimate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, a widely used formula. Multiplying your BMR by your activity level gives your estimated daily maintenance calories (TDEE). Comparing that to what you actually eat each day gives a rough weekly trend: about 3,500 calories above or below maintenance works out to roughly one pound of gain or loss per week.

This is only an estimate. Individual metabolism, muscle mass, hormones, medications and many other factors can shift your real numbers. It is not a substitute for medical or nutritional advice. If you have a health condition, are pregnant, or are considering a significant change in your diet or exercise, talk with a doctor or registered dietitian first.

For top tips on how to get your weight and physique under control, check out our blog: