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BMI Calculator for Men & Women (lb/ft or kg/cm)

Free BMI calculator for adults. Enter your height and weight in pounds/feet or kg/cm to get your body mass index, weight category and healthy weight range.

Calculate your BMI

Switch units with the lb/ft – kg/cm toggle at the top of the page. Nothing you enter leaves your device.

What is BMI?

Body mass index (BMI) is a simple number calculated from your weight and height. It is used by doctors and public health agencies, including the U.S. Centers for Disease Control and Prevention (CDC), as a quick screening tool for weight categories that may be linked to health problems.

The BMI formula

Metric: BMI = weight (kg) ÷ height (m)²
US units: BMI = 703 × weight (lb) ÷ height (in)²

Example: a person who is 5 ft 10 in (70 inches) and weighs 180 lb has a BMI of 703 × 180 ÷ 4,900 = 25.8.

BMI categories for adults

BMICategory
Below 18.5Underweight
18.5 – 24.9Healthy weight
25.0 – 29.9Overweight
30.0 – 34.9Obesity class 1
35.0 – 39.9Obesity class 2
40 and aboveObesity class 3 (severe)

These categories are the same for adult men and women. For children and teens, BMI is interpreted using age- and sex-specific percentiles, so this calculator is not suitable for people under 18.

Limitations of BMI

BMI is useful because it is quick and free, but it has important limitations:

  • It does not measure body fat. A muscular athlete can have a BMI over 25 with low body fat.
  • It ignores fat distribution. Fat around the waist (visceral fat) carries more health risk than fat on the hips. Waist circumference adds useful information: a waist over 40 inches (102 cm) for men or 35 inches (88 cm) for women is linked to higher risk.
  • It does not account for age, sex or ethnicity differences in body composition. Some health organizations use lower BMI cut-offs for people of Asian descent.

For a more complete picture, combine BMI with our body fat calculator and your waist measurement.

What to do with your result

If your BMI is in the healthy range, focus on staying active and building strength. If it is above 25, a moderate calorie deficit combined with strength training is the most effective way to lose fat while keeping muscle. Use the plan builder for your calorie target and program. If your BMI is under 18.5, consider speaking to a doctor and look at our muscle gain meal plans.

How to use your result

A calculator gives you a starting point, not a final answer. The most reliable way to use any fitness number is the measure → act → review loop:

  1. Measure: record your result today, along with your morning body weight, waist measurement and a few photos.
  2. Act: follow a matching plan for 2–4 weeks. Use the plan builder to get a workout program and a 7-day meal plan that fit your numbers.
  3. Review: compare your weekly averages and measurements. If things are moving in the right direction at a sustainable pace, keep going. If not, adjust by small amounts (100–200 calories, one extra workout, 2,000 extra steps) and review again.

US and metric units

Every HelloMyTrainer calculator works in both systems. Use the lb / ft or kg / cm switch at the top of the page; your choice is remembered on this device for all calculators and meal plans. Useful conversions: 1 kg = 2.2 lb, 1 inch = 2.54 cm, 1 foot = 30.48 cm, 1 liter = 33.8 US fluid ounces.

Who should be careful with these numbers

These calculators are designed for healthy adults aged 18 and over. They are not suitable for children or teenagers, pregnant or breastfeeding women, people with a history of eating disorders, competitive athletes with very high muscle mass, or people with medical conditions that affect weight, metabolism or fluid balance (such as heart failure, kidney disease or thyroid disorders). If any of these apply to you, please speak with your doctor or a registered dietitian before using the results.

Your privacy

We never ask for your name, email or any personal details to use our tools. The calculations run in your web browser and the numbers you type are not sent to our servers. See our Privacy Policy for details.

Frequently asked questions

Is BMI different for men and women?

The adult BMI formula and categories are the same for men and women. However, women naturally carry more body fat than men at the same BMI.

What is a healthy BMI?

For most adults, a BMI between 18.5 and 24.9 is considered healthy.

Is BMI accurate for bodybuilders?

No. People with a lot of muscle often have a high BMI without excess fat. Use body fat percentage instead.

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Results are estimates for healthy adults and are not medical advice.