BMI Calculator | Morph

Morph's BMI calculator gives you your body mass index in a moment. Enter your height and weight in either metric or imperial units, and you'll see your BMI number along with the standard weight category it falls into. The whole thing runs in your browser, so your measurements never leave your device.

What BMI is

Body mass index is a simple ratio of weight to height. The formula is your weight in kilograms divided by your height in meters squared (kg/m²). It was designed as a quick population-level screen, an easy way to flag whether someone's weight sits in a typical range for their height. The standard adult categories are:

The calculator does the math for you in either unit system and tells you which band your result lands in.

What BMI can and can't tell you

BMI is useful precisely because it's simple, but that simplicity is also its limit. It looks only at height and weight, it doesn't know the difference between muscle and fat. A very muscular athlete can register as "overweight" while carrying little body fat, and BMI can under-flag people who have lost muscle. It also wasn't designed for children, pregnant people, or the elderly, who use different references.

Treat your number as one rough data point, not a diagnosis. Waist measurement, body composition, fitness, and bloodwork all paint a fuller picture. For anything health-related, talk to a doctor who can weigh the full context. This tool is for general information, not medical advice.

Private and instant

Your weight and height are personal. Morph calculates BMI entirely in your browser, so the numbers you enter are processed on your own device and never sent to a server. There's no sign-up, no tracking, and nothing stored. Type your figures, read your result, and close the tab, nothing follows you.

It's a quick way to check where you stand against the standard ranges, compare metric and imperial, or recheck after a change in weight, all without handing your health data to anyone.

How to use

  1. Choose your units — Pick metric (centimeters and kilograms) or imperial (feet/inches and pounds), whichever you measure in.
  2. Enter height and weight — Type your current height and weight. The values are read only in your browser and never uploaded.
  3. See your BMI — The calculator instantly shows your body mass index number and the standard weight category it falls into.
  4. Interpret with context — Use the result as a general guide. Because BMI ignores muscle and body composition, treat it as one data point and consult a doctor for anything health-related.

Frequently asked questions

How is BMI calculated?

BMI is your weight in kilograms divided by your height in meters squared (kg/m²). If you enter imperial units, the calculator converts them first, so you get the same standard result either way.

What is a healthy BMI range?

For adults, the standard categories are: under 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight, and 30 or above obese. These are general screening ranges, not a personal health verdict.

Is BMI accurate for everyone?

Not entirely. BMI only uses height and weight, so it can misjudge very muscular people and isn't meant for children, pregnant people, or the elderly. Use it as a rough guide alongside other measures and professional advice.

Are my measurements kept private?

Yes. The calculation runs entirely in your browser. Your height and weight are never uploaded, stored, or tracked, so your personal data stays on your device.

Does this replace medical advice?

No. It's a general-information tool. For health decisions, talk to a doctor who can consider your full situation, including body composition, fitness, and medical history.

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