BMI calculator: check my BMI

Built by Nitin Raja · Last updated October 24, 2026

What is BMI?

Body mass index (BMI) is a quick way to compare height and weight with a single number. Doctors use it as a first screening step for adults because it's easy to calculate and works reasonably well across large groups of people. It doesn't measure body fat directly, and it can't tell muscle from fat, but it's a useful starting point - especially when you track it over time.

This BMI calculator combines two tools in one: a height checker that can measure you with your phone camera, and a weight box that accepts kilograms or pounds. That matters more than it sounds, because a wrong height is the most common reason a BMI is off.

How to check BMI

1. Get your height right. Tap 📏 to measure with the camera, or type it as 5'10 or 178.
2. Weigh yourself in the morning, after using the bathroom and before eating, in light clothes.
3. Enter your weight in kg or lb. Your BMI, category and healthy weight range appear straight away.

The BMI formula

BMI is your weight in kilograms divided by your height in metres, squared:

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

For someone who is 1.75 m and 70 kg: 1.75 × 1.75 = 3.06, and 70 ÷ 3.06 = 22.9. In imperial units, 5′ 9″ is 69 inches and 70 kg is 154 lb: 703 × 154 ÷ (69 × 69) = 22.7 - the tiny difference is rounding in the conversion.

BMI categories for adults

Some health bodies use lower cut-offs for adults of South Asian, Chinese and other East Asian heritage, because health risks start to rise at a lower BMI in those groups. In India, for example, a BMI of 23 or more is often treated as overweight. If that applies to you, read your result with that in mind.

How to read the height and weight chart

The height and weight chart on this page lists every height from 4′ 10″ to 6′ 6″ with the weight range that gives a BMI between 18.5 and 24.9. Find your height in the left column and read across: that's the healthy weight range for your height in kilograms and pounds. Think of it as a weight and height comparison chart for adults. It's the fastest way to compare height and weight without doing any maths - and it's what most people mean when they search for a weight and height checker.

For example, at 5′ 7″ (170 cm) a healthy weight is roughly 54-72 kg (118-159 lb). At 6′ 0″ (183 cm) it's roughly 62-83 kg (136-184 lb). The ranges are wide on purpose: frame size, muscle and age all shift where you naturally sit.

Why your height matters so much

Height is squared in the formula, so a small height error has a bigger effect than a small weight error. Being 2 cm out on your height changes BMI by more than 2%. Many adults haven't measured themselves in years and carry around a number from school or a driving licence - or have lost a little height with age. Measuring with the camera first gives the BMI calculator a real starting point.

Why we built this BMI calculator

Before building CheckMyHeight, I tested a lot of height and sizing websites to see what people need and what gets in the way. BMI calculators are everywhere and the arithmetic is the same in all of them, so what goes wrong is the input. Height is squared in the formula, which makes it the number that matters most, yet most calculators simply trust whatever height you remember, often a figure from school or an old ID card. Many also show a single category word without the healthy weight range for your height, which is the part people can act on.

Because this site already measures height with the phone camera, we put the two together: measure your height first, then add your weight, and see the BMI next to the weight range that would be healthy at that height.

What this BMI calculator measures

Two inputs: height (typed in centimetres, metres or feet and inches, or measured with the camera button) and weight in kilograms or pounds (pounds are converted with 1 lb = 0.45359237 kg). The calculator then works out:

• BMI = weight (kg) ÷ height (m)², shown to one decimal place.
• The category with the World Health Organization adult cut-offs: under 18.5 underweight, 18.5 to 24.9 healthy, 25 to 29.9 overweight, 30 or more obesity.
• Your healthy weight range: the weights that give a BMI of 18.5 to 24.9 at your height, in the unit you chose.
• A position marker on a 0 to 40 BMI scale.

The cut-offs were last checked on 24 October 2026. What it does not measure: body fat, muscle, waist size or where fat is carried, and it does not use the lower cut-offs some health bodies set for adults of Asian heritage (the guide explains them). It is for adults aged 20 and over; children's BMI needs age- and sex-specific growth charts. It is a screening number, not medical advice.

Why this BMI calculator is different

• Measure your height, not just type it. The camera button measures you with the phone in about 30 seconds.
• The healthy weight range for your height comes with every result, and the chart on this page lists it for every height from 4′ 10″ to 6′ 6″.
• The formula is shown with a worked example in metric and imperial, and the guide says plainly when BMI misleads.
• Any units for height and weight.
• No account and nothing sent. The calculation runs in your browser; height and weight are not stored or uploaded.
• Both boxes start empty, and no BMI appears until you enter your own height and weight.

When BMI is misleading

• Athletes and very muscular people often come out as "overweight" while being lean, because muscle is dense. Many professional footballers and rugby players have a BMI over 25.
• Older adults can have a "healthy" BMI while carrying too little muscle.
• Children and teenagers can't use adult categories. Their BMI is compared with growth charts for their exact age and sex, which is something a paediatrician does.
• Pregnancy changes weight in ways BMI doesn't account for.

Waist measurement adds useful information: as a rough guide, a waist of less than half your height is a good sign regardless of BMI.

Track your BMI over time

A single BMI is a snapshot; the trend is what's useful. Check your BMI every few months under the same conditions - morning, before breakfast, same scale - and re-measure your height once a year, because adults slowly lose height with age. A steady number is reassuring. A change of more than one BMI point in a few months, up or down, is worth noticing, especially if you weren't trying to gain or lose weight.

Compare height and weight with celebrities

Curious how your build compares with famous athletes? The celebrity heights and weights list shows height, weight and BMI for hundreds of sports stars and other public figures - a good reminder of how misleading BMI can be for very muscular people. For height alone, see the average height for men and women or put yourself on the height comparison chart.

A screening number, not a diagnosis

This BMI calculator is for adults aged 20 and over, and it's for information only. If your result worries you - or if you've gained or lost weight without trying - talk to a doctor, who can look at the whole picture rather than a single number.