BMI Calculator

Runs in your browserNo sign-up required

Height (cm)

Weight (kg)

Your BMI22.5

CategoryNormal

Healthy weight range for your height53.5–72.0 kg

This is a general estimate based on standard published formulas, not a medical assessment — it doesn’t account for your individual health history. Results are informational only and aren’t a substitute for advice from a doctor or qualified professional. Read the full disclaimer.

More Than Just a Number

Most BMI calculators stop at telling you which category your current weight falls into. This one goes a step further and also shows the actual healthy weight range — in kg or lb — for your exact entered height, so you can see not just “where am I now” but “what range am I aiming for,” which is the more useful number if you're actually trying to reach or maintain a healthy weight.

How to Use This Calculator

1Choose metric or imperialSwitch units depending on whether you know your height and weight in kg/cm or lb/ft-in.
2Enter your height and weightYour BMI and weight category update instantly as you type.
3Check your healthy weight rangeSee the specific weight range for your exact height, not just where your current weight sits.

Understanding BMI Categories

1Underweight — below 18.5May indicate insufficient nutrition or an underlying health condition. If this applies to you consistently, it's worth discussing with a doctor rather than treating the number alone as the full picture.
2Normal weight — 18.5 to 24.9Associated with the lowest average health risk in most population studies, though BMI alone doesn't account for muscle mass, frame size, or body composition.
3Overweight — 25 to 29.9Associated with a somewhat higher average risk of certain conditions, though this varies significantly by individual factors BMI doesn't measure, like muscle mass and fat distribution.
4Obese — 30 and aboveAssociated with a higher average health risk in most studies. As with every category here, this is a population-level statistical association, not an individual diagnosis.

Limitations of BMI You Should Know

BMI doesn't distinguish muscle from fat — a muscular athlete can register as "overweight" despite having very low body fat.
It doesn't account for age, sex, bone density, or where fat is distributed on the body, all of which affect actual health risk.
It was originally developed as a population-level statistical tool, not a precise individual diagnostic measure.
A single BMI number can't replace an actual conversation with a doctor about your specific health — treat it as one data point, not a verdict.

The BMI Formula

BMI = Weight (kg) / Height (m)²

Weight — in kilograms (pounds are converted to kg first if you use imperial units)

Height — in meters, squared (feet/inches are converted first)

Example: 170 cm and 65 kg → height = 1.70 m, BMI = 65 / 1.70² ≈ 22.5 (Normal range). For this height, a "normal" BMI (18.5–24.9) works out to roughly 53.5–72.0 kg.

BMI is a simple, widely-used screening number, not a diagnosis — it doesn't account for muscle mass, bone density, age, or sex, which is why an athlete can show as "overweight" despite low body fat. Use it as a starting point, not a verdict.

Frequently Asked Questions

How is BMI calculated?

BMI = weight (kg) ÷ height (m)². In imperial units, it's [weight (lb) ÷ height (in)²] × 703. This calculator does the conversion for you regardless of which unit system you enter your numbers in.

What does the "healthy weight range" show that a BMI category doesn't?

A BMI category just tells you where your current weight falls. The healthy weight range instead converts the entire healthy BMI band (18.5–24.9) back into an actual weight range in kg or lb for your specific height — a more directly useful number if you're working toward or maintaining a target weight.

Is BMI accurate for everyone?

No — it's a broad screening tool, not a precise individual measure. It doesn't account for muscle mass, so athletes and very muscular people are commonly misclassified as overweight or obese despite having low body fat. It's most useful as a rough, quick indicator rather than a final answer.

What BMI range is considered healthy?

For most adults, 18.5 to 24.9 is classified as the normal/healthy range. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese — though these thresholds are population averages, not individual guarantees of health status.

Should I use BMI alone to decide if I need to lose or gain weight?

No — use it as one reference point alongside how you actually feel, your body composition, and ideally a conversation with a doctor, especially if your number sits outside the normal range or you have specific health concerns.

Is this BMI calculator free to use?

Yes, completely free, with no sign-up, and every calculation happens locally in your browser.