BMI Calculator, With the Honest Caveats
Get your number, your range, and the caveat most calculators skip: your waist tells you more.
Type height and weight and your number appears instantly.
If you are buying a scale
Any consistent scale works if you weigh at the same time each morning. Smart scales that log the trend automatically make the habit stick, and the trend matters more than any single day.
Buying through this link supports the free library with a small commission. It never changes a pick.
Add your height in your profile and this sharpens: BMI is weight over height squared.
Saved here, it also updates your health score and your record.
Common questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered the healthy range. From 25 to 29.9 counts as overweight, and 30 or above counts as obese. BMI is a screening number, not a diagnosis, so use it as a starting point for a conversation with your own doctor.
Why is BMI misleading for muscular or older people?
BMI only compares weight to height, so it cannot tell muscle from fat. A muscular person can score as overweight while carrying very little fat, and an older person can have a normal BMI while having lost muscle and gained fat around the middle. That is why doctors often look at waist size and overall health alongside BMI.
Why are the BMI cut-offs lower for Asian people?
Research shows that people of Asian background tend to develop diabetes and heart disease at lower BMI levels than others. Because of this, many health bodies use a cut-off of 23 for overweight and 27.5 for obesity in Asian adults instead of 25 and 30. If this applies to you, the standard chart may understate your risk, so discuss it with your doctor.
Does waist size matter more than BMI?
For predicting health problems, waist size is often the more useful number, because fat stored around the organs in your belly is the kind most linked to diabetes and heart disease. A common rule of thumb is to keep your waist under half your height. A large waist with a normal BMI is still worth raising with your doctor.
Is BMI actually a good measure?
It is a decent population screen and a blunt personal one. It cannot tell muscle from fat, so athletes score high while unfit slim people pass. For individuals, waist size adds the missing information, since belly fat drives most of the risk: a waist under half your height is a better everyday target than any BMI decimal.