Home › Health Calculators › BMI Calculator
BMI Calculator
Find your Body Mass Index in seconds. Enter your height and weight — US units (feet, inches, pounds) by default, metric if you prefer — and instantly see your BMI, your category, and the healthy weight range for your height. It runs entirely in your browser: no account, and nothing you enter is saved or sent anywhere.
Your height & weight
Results update as you type or slide. Adult categories (ages 20+) from the CDC.
Your result
Your BMI of 25.8 falls in the Overweight range (25.0–29.9). For your height, the healthy range tops out at 173.6 lb.
How to use this BMI calculator
- Pick your units — US (feet/inches and pounds) or metric (cm and kg), using the toggle above the inputs.
- Enter your height — for example 5 ft 10 in (or 178 cm). Use your barefoot height, measured in the morning.
- Enter your weight — for example 180 lb (or 81.6 kg). Weigh yourself in light clothing, on a flat surface.
- Read your result instantly — your BMI appears at the top (25.8 in the example), along with your category (Underweight, Healthy, Overweight or Obese), the healthy weight range for your height, and how many pounds you are from that range.
- Use the healthy range, not just the number — if you are above it, the "to reach the healthy range" figure tells you exactly how much to lose; if you are below it, how much to gain.
Nothing is saved or sent anywhere — the calculation runs entirely in your browser, and you can change the numbers as often as you like.
How BMI is calculated
Body Mass Index compares your weight to your height. It was designed as a quick population-level screening tool, and US doctors still use it as a first check before looking at waist size, blood pressure, labs and lifestyle.
Worked example: a person who is 5 ft 10 in tall (70 inches) and weighs 180 lb has a BMI of 703 × 180 ÷ 70² = 25.8 — in the Overweight category. At that height, the healthy BMI band of 18.5–24.9 works out to 128.9–173.6 lb, which is the range this calculator shows you.
Adult BMI categories (CDC)
| Category | BMI | What it generally means |
|---|---|---|
| Underweight | Below 18.5 | Below the healthy range — worth discussing with a clinician, especially if unintentional. |
| Healthy | 18.5 – 24.9 | The range associated with the lowest average health risk for most adults. |
| Overweight | 25.0 – 29.9 | Above the healthy range; risk of conditions like type 2 diabetes starts to rise. |
| Obese | 30.0 and above | Classes I (30–34.9), II (35–39.9) and III (40+). A clinician can help with a plan. |
Know the limits: BMI can't tell muscle from fat, so athletes often score "overweight" while being lean. It also doesn't show where fat is carried — waist circumference adds useful context. Older adults and different ethnic groups can have different risk at the same BMI. Use this number as a starting point for a conversation, not a verdict.
Frequently asked questions
How is BMI calculated?
In US units: BMI = 703 × weight in pounds ÷ (height in inches)². In metric: BMI = weight in kilograms ÷ (height in metres)². This calculator does both — just switch the unit toggle.
What is a healthy BMI for adults?
For adults 20 and older, the CDC ranges are: Underweight below 18.5, Healthy 18.5–24.9, Overweight 25.0–29.9, and Obese 30.0 or higher.
What is the healthy weight range for my height?
It's the weight band that gives a BMI of 18.5–24.9 at your height. For example, at 5 ft 10 in it's 128.9–173.6 lb. Your personal healthy range appears next to your result above and updates with your height.
Is BMI accurate for athletes and muscular people?
Not always. BMI treats all weight the same, so a muscular athlete can land in "Overweight" with low body fat. Body-fat percentage, waist size and overall fitness give a fuller picture.
Can I use this BMI calculator for my child or teenager?
The adult cut-offs here don't apply under age 20. For ages 2–19, doctors use BMI-for-age percentiles that account for growth and sex. Ask your pediatrician to interpret a child's BMI.
How can I lower my BMI safely?
Small, steady changes work best for most people: regular activity (the CDC suggests 150 minutes of moderate exercise a week for adults), balanced meals, enough sleep, and cutting sugary drinks. Aim for gradual loss and get personalised guidance from a clinician or registered dietitian.
Is my height and weight data saved?
No. Everything is calculated in your browser the moment you type. Nothing is sent to a server, stored in cookies, or tracked as personal health data.