BMI Calculator

Body Mass Index and healthy weight range

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100% freeNo signupRuns in your browser

Built by WOWHOW Team · 14+ yrs engineering

BMI Calculator is a free, browser-based tool that lets you body mass index and healthy weight range — with zero signup, zero installation. Your data never leaves your browser. Part of 138+ free developer and business tools at wowhow.cloud, built and maintained by a team with 14+ years of hands-on development experience.

TOOLBMI Calculator

Height

100 cm170 cm220 cm

Weight

30 kg70 kg200 kg

Age (optional)

10100

Sex (optional — affects context note)

Your BMI

24.2

Normal weight

1018.52530354045+

UnderNormalOverOb. IOb. IIOb. III

Healthy Weight Range for Your Height

53.5–72.0kg

Based on WHO normal BMI range (18.5–24.9)

What This Means

You are in a healthy weight range according to the WHO standard. Maintaining this range through balanced nutrition and regular physical activity supports long-term health.

WHO BMI Categories

Underweight0 – 18.49

Normal weight18.5 – 24.99

Overweight25 – 29.99

Obese Class I30 – 34.99

Obese Class II35 – 39.99

Obese Class III≥ 40

BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, or body fat distribution. Always consult a healthcare professional for personalized health advice.

About BMI Calculator

Body Mass Index is a population-level screening tool developed by the WHO that uses the ratio of weight to height squared to classify weight status. While it cannot diagnose individual health conditions, it provides a standardized starting point for discussions about healthy weight ranges and correlates with disease risk across large populations. The formula was standardized in 1972 and remains the most widely used weight classification metric in clinical and research settings.

How It Works

BMI is calculated as weight (kg) divided by height in meters squared: BMI = kg ÷ m². For imperial inputs, the calculator first converts pounds to kilograms (÷ 2.2046) and feet/inches to meters (× 0.3048 for feet, × 0.0254 for inches) before applying the formula.

The result is mapped to WHO weight categories: underweight (< 18.5), normal (18.5–24.9), overweight (25.0–29.9), obese class I (30.0–34.9), obese class II (35.0–39.9), and obese class III (≥ 40).

The healthy weight range for your height is back-calculated by solving BMI = weight/height² for weight at both the 18.5 and 24.9 boundaries. This gives you a concrete target range in your preferred unit system.

Who Is This For

A 34-year-old office worker entering their height and weight to check whether their current 27.4 BMI puts them in the overweight range before a company health screening.

A dietitian calculating a client's BMI and healthy weight range as part of an initial consultation to set a realistic weight loss target.

A fitness coach tracking monthly BMI changes for 10 clients to document progress in a structured way alongside body composition measurements.

A medical student practicing the BMI formula manually and cross-checking against a calculator to verify their arithmetic on case study problems.

Scope note: BMI does not measure body fat percentage and cannot distinguish between muscle and fat mass. Athletes with high muscle mass often register as "overweight" despite low body fat. BMI is also less predictive for older adults who have lost muscle mass, and research supports using lower threshold values for people of South and East Asian descent.

How to Use

Enter your height — toggle between cm and ft/in

Enter your weight — toggle between kg and lbs

View your BMI score and weight category instantly

Check the BMI scale to see where you fall

See the healthy weight range for your height

Frequently Asked Questions

BMI (Body Mass Index) is calculated by dividing your weight in kilograms by the square of your height in meters: BMI = kg/m². For example, a person who is 70 kg and 1.75 m tall has a BMI of 22.9.

According to the WHO, a BMI between 18.5 and 24.9 is considered normal/healthy weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.

BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat — a muscular athlete may have a high BMI but low body fat. It is less accurate for older adults, children, and people with high muscle mass.

Yes. All calculations happen entirely in your browser. No personal data is ever sent to any server.

Yes. The WHO and several Asian health authorities recommend lower BMI thresholds for people of Asian descent. The Asia-Pacific guidelines suggest overweight begins at 23 (vs. 25 in standard WHO ranges) and obesity at 27.5 (vs. 30). This is because metabolic risk factors tend to appear at lower BMI values in Asian populations.

Healthy weight range = BMI 18.5 to 24.9 × height² (in meters). For a 170 cm (1.70 m) person: 18.5 × 1.70² = 53.5 kg (lower bound) and 24.9 × 1.70² = 71.9 kg (upper bound). The calculator shows this range automatically beneath your BMI result.

This calculator uses the adult WHO formula (BMI = kg/m²). For children and teenagers under 20, BMI must be interpreted using age- and sex-specific growth charts (BMI-for-age percentiles), not fixed adult cutoff values. Use a dedicated pediatric BMI calculator for anyone under 20.