BMI Calculator
BMI Calculator Free Online Tool
Our bmi calculator free online tool tells you your body mass index in seconds. Enter your height and weight, choose metric (kg and cm) or imperial (lb and ft/in), and the result appears instantly with your weight category. There is nothing to install and no sign-up, and your numbers stay in your browser.
Free Online BMI Calculator for Adults
This free online bmi calculator is made for adults aged 20 and over. BMI is a quick screening number that compares your weight to your height, so it is a useful starting point before talking to a doctor or planning a fitness goal. If you like tracking your progress with tidy visuals, build a matching set of colors with our Color Palette Generator.
How to Figure Out Body Mass Index Formula
If you want to know how to figure out body mass index formula, it is simple: BMI equals weight divided by height squared. In metric units the formula is BMI = weight (kg) ÷ height (m)². In imperial units it is BMI = 703 × weight (lb) ÷ height (in)². The calculator above applies the right version automatically when you switch units.
How to Calculate Body Mass Index Manually
Here is how to calculate body mass index manually in three steps, using a person who weighs 70 kg and is 1.75 m tall:
- Convert your height to meters (175 cm = 1.75 m).
- Multiply your height by itself: 1.75 × 1.75 = 3.0625.
- Divide your weight by that number: 70 ÷ 3.0625 = 22.9.
For imperial units, a person who weighs 160 lb and is 66 inches tall gets 160 ÷ 4,356 × 703 = 25.8. Use the calculator to double-check your own math.
BMI Categories Explained
Once you have your number, compare it with the standard adult ranges used by the CDC and the World Health Organization:
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
Body Mass Index Chart by Age and Height
People often search for a body mass index chart by age and height, but for adults the ranges above are the same at every age. Age only changes the rules for children and teens aged 2 to 19, who are measured with BMI-for-age percentiles that account for sex and growth. For adults, height is what changes your healthy weight range. This chart shows the weight range that falls in the healthy BMI band (18.5 to 24.9) at common heights:
| Height | Healthy weight range |
|---|---|
| 5'0" (152 cm) | 95 – 127 lb (43 – 58 kg) |
| 5'3" (160 cm) | 105 – 141 lb (47 – 64 kg) |
| 5'6" (168 cm) | 115 – 154 lb (52 – 70 kg) |
| 5'9" (175 cm) | 125 – 169 lb (57 – 76 kg) |
| 6'0" (183 cm) | 136 – 184 lb (62 – 83 kg) |
| 6'3" (191 cm) | 148 – 199 lb (67 – 90 kg) |
What Is a Healthy Body Mass Index for Women
Many readers ask what is a healthy body mass index for women. The answer is the same range used for men: 18.5 to 24.9. Keep in mind that women naturally carry more body fat than men at the same BMI, and the number does not account for pregnancy, breastfeeding or menopause. Some health bodies also suggest lower cut-offs for people of Asian descent, so ask your doctor which range fits you best.
Ideal Weight Chart Based on Height and Body Type
An ideal weight chart based on height and body type adjusts the healthy range for your frame. A simple rule of thumb is to aim for the lower half of your range if you have a small frame, the middle if you have a medium frame, and the upper half if you have a large frame. BMI cannot see muscle, so athletes and very muscular people can score as overweight while having low body fat. Treat the result as a guide, not a verdict.
Simple BMI Calculator Online
If you want a simple bmi calculator online, this one keeps the controls to the essentials: unit type, height and weight. The result and category update instantly, so there is no generate button to press. Protect your saved results and accounts for health apps with a strong login from our Random Password Generator.
Quick BMI Calculator for Men and Women
This quick bmi calculator for men and women works for any adult and runs entirely in your browser. Share your wellness plan or a printable chart with friends through a scannable link from our QR Code Generator, or give your health blog a polished look with a custom icon from the Favicon Generator. Developers building health apps can also try the UUID Generator for unique record IDs.
Tips for using your BMI result
- Measure your height without shoes and weigh yourself at the same time of day for consistent results.
- Use BMI together with waist size, activity level and blood tests for a fuller picture of your health.
- Re-check every few months instead of every day, because small daily changes are mostly water.
- Talk to a doctor before making major diet or exercise changes, especially if your BMI is under 18.5 or over 30.
Frequently asked questions
Is this bmi calculator really free? Yes. It is free, requires no registration, and has no usage limits.
Is my data uploaded anywhere? No. Your height and weight stay in your browser.
Is BMI accurate for everyone? Not always. It is a screening tool and does not measure body fat directly, so muscle mass, age and body frame can affect how well it fits you.
Is this tool a substitute for medical advice? No. It gives general information only. Please consult a healthcare professional about your personal health.
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