Body Mass Index (BMI) is a number calculated from your weight and height. It is used as a screening tool for weight categories: Underweight (< 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30+).

Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest to maintain basic life functions. This calculator uses the Mifflin-St Jeor equation, which is widely considered the most accurate for most people.

Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor. It represents the total calories you burn per day including exercise and daily activities.

Is BMI accurate for everyone?

BMI is a useful screening tool but does not account for muscle mass, bone density, or fat distribution. Athletes may have a high BMI without being overweight, and older adults may have a normal BMI while having excess body fat.

How do I lose weight safely?

A deficit of 500 kcal/day below your TDEE typically results in about 0.5 kg (1 lb) of weight loss per week. Consult a healthcare provider before making significant dietary changes.

BMI Calculator

Name: BMI Calculator
Availability: InStock
Author: Nham Vu

Enter your height, weight, age, and activity level to instantly see your BMI, weight category, ideal weight range, and daily calorie target.

Body Measurements

Height

Weight

Age

Sex

Male Female

Activity Level

Results

Real-time calculation

Enter height and weight to see results instantly.

Add age and sex to calculate calorie needs.

Summary

Enter your height, weight, age, and activity level to instantly see your BMI, weight category, ideal weight range, and daily calorie target.

How it works

Enter your height in cm or feet and inches.
Enter your weight in kg or pounds.
Optionally enter your age, sex, and activity level for calorie estimates.
Results update instantly — no button needed.

Use cases

Check if your weight is in a healthy range for your height.
Calculate the calorie deficit needed to lose weight safely.
Find the ideal weight range to aim for during a fitness program.
Estimate your maintenance calories before starting a diet.

Frequently Asked Questions

Related tools

Bmr Calculator Tdee Calculator Body Fat Calculator

Last updated: 2026-06-02 · Reviewed by Nham Vu