BMI Calculator
Calculate your body mass index from your height and weight, and see which weight range is healthy for your height.
Your BMI
22.9
Healthy weight
Healthy weight for your height
56.7 – 76.6 kg
Please note: This is a general guideline, not a diagnosis or medical advice. Age, sex, build and muscle mass are not taken into account. If you have questions about your health, talk to your doctor.
How this number is calculated
The blocks use your input. Change a value above and they update with it.
Step 1 · Height in meters
Step 2 · Height squared
Step 3 · BMI
How the calculation works
BMI is your weight in kilograms divided by the square of your height in meters. For adults, a BMI from 18.5 up to 25 counts as a healthy weight.
BMI says nothing about muscle mass or where body fat sits. Use the result as a guideline, not as a diagnosis. Inches, pounds and stones are converted to centimeters and kilograms first. The healthy weight for your height is the weight that gives a BMI from 18.5 up to 25: 18.5 and 25 times your height in meters squared.
Formula
BMI = weight (kg) ÷ (height (m) × height (m)). Healthy weight = 18.5 to 25 × height (m) × height (m).
Assumptions
- The calculation is meant for adults: 18 and over in the UK (NHS), 20 and over under the US CDC charts.
- The cut-offs are the WHO cut-offs for adults: 18.5, 25 and 30.
- Muscle mass, build and fat distribution are not taken into account.
- Height and weight are measured without shoes and heavy clothing.
- During pregnancy the result says little; the calculation is not meant for that.
Example calculations
The button fills in the calculator above, so you can carry on from there.
-
Well within the healthy range
Your BMI
22.9 · Healthy weight
Height 175 cm · Weight 70 kg
-
Above the healthy range
Your BMI
29.3 · Overweight
Height 180 cm · Weight 95 kg
-
Just below the healthy range
Your BMI
17.7 · Underweight
Height 168 cm · Weight 50 kg
Frequently asked questions
What is a healthy BMI?
Under the well-known WHO categories, a BMI from 18.5 up to 25 counts as healthy for adults. Below that is underweight, above it overweight, and 30 or more is obesity.
What weight fits my height?
The calculator works out which weights give a BMI from 18.5 up to 25 at your height. At 1.75 m (about 5 ft 9 in) that is 56.7 to 76.6 kg.
Why can my BMI be misleading?
BMI only looks at height and weight, not at what that weight is made of. Muscle is denser than fat, so a muscular person can have a high BMI without much body fat. A doctor or dietitian can look beyond BMI.
Does BMI apply to children?
No, these cut-offs are for adults. For children and teens (2 to 17 in the UK, 2 to 19 in the US), a healthy weight depends on age and sex, so growth charts with their own cut-offs are used. A doctor can tell you more.
Does BMI work for older adults?
BMI says less about older adults: muscle mass decreases with age and body build changes. Some health bodies therefore use wider cut-offs; the Dutch Nutrition Centre, for example, counts 22 to 28 as healthy from age 70. This calculator uses the standard adult cut-offs. A doctor can say what fits your situation.
Can I use BMI during pregnancy?
No, BMI says little during pregnancy, because weight naturally goes up. Midwives and doctors do sometimes look at the BMI from before the pregnancy. Questions about weight during pregnancy can go to a midwife or doctor.
Do the cut-offs differ by ethnic background?
In the UK, the NHS uses lower cut-offs for people from a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background: a BMI of 23 to 27.4 counts as overweight and 27.5 or more as obese. This calculator uses the standard WHO cut-offs.
Sources and checks
Sources
- Calculate your body mass index (BMI) for adults | NHS
- Overweight and obesity in adults | NHS
- Obesity and overweight | WHO
- Malnutrition in women | WHO
How we check it
This calculator has 10 fixed checks: 8 calculations with a result that is fixed in advance, and 2 cases of invalid input that must be rejected. They all run automatically every time we publish; if one fails, the calculator does not go live.
See the calculations
- Height 175 cm · Weight 70 kg → Your BMI 22.9
- Height 180 cm · Weight 59.94 kg → Your BMI 18.5
- Height 200 cm · Weight 91.4 kg → Your BMI 22.9
- Height 69 in · Weight 154 lb → Your BMI 22.7
- Height 69 in · Weight 11 st → Your BMI 22.7
- Height 100 cm · Weight 300 kg → Your BMI 300
- Height 180 cm · Weight 95 kg → Your BMI 29.3
- Height 168 cm · Weight 50 kg → Your BMI 17.7
Changes
- : Clearer help texts for the fields. Added the wider cut-offs for older adults, the NHS cut-offs for some ethnic backgrounds and the CDC age range. Sources added.
- : Added an explanation, assumptions, worked examples and frequently asked questions.
- : First version.
Last reviewed: · How we build and check our calculators
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