BMI Calculator for Women

What BMI can and can't tell you

Body mass index is a simple formula: weight in kilograms divided by height in meters, squared. The World Health Organization sorts the result into population categories, under 18.5, 18.5 to 24.9, 25 to 29.9, and 30 or above, that were built from large population studies, not from any single person's health. Those labels describe where a number sits in a distribution. They were never meant to describe an individual, and this calculator won't address you as one, either; the result says where your number falls, not what you are.

What the number can't see

BMI can't distinguish muscle from fat, so a muscular or highly active body can land in a higher category without that reflecting body composition at all. It also can't see where fat sits on the body, which matters more for cardiometabolic risk than total weight does. The formula and its cut-offs were derived largely from studies of white European men, and research has repeatedly shown those same cut-offs perform differently for South Asian and East Asian populations, who can carry higher metabolic risk at BMI numbers the standard categories would call normal. And underneath all of that: BMI says nothing about how healthy any individual actually is. It's a screening statistic for populations, not an assessment of a person.

Waist-to-height ratio: the companion metric

If you enter a waist measurement, this calculator also shows your waist-to-height ratio, waist divided by height, in the same units. A commonly cited reference point is 0.5, keeping your waist under half your height, described here plainly rather than as a rule. Because it reflects where weight sits rather than just how much there is, research has found waist-to-height ratio correlates with cardiometabolic risk at least as well as BMI, and in a number of studies, better. It's not a replacement for BMI on this page; it's shown alongside it because it's the genuinely useful addition a bare BMI number is missing.

BMI and PCOS

BMI comes up constantly in PCOS care, because weight and insulin resistance interact in both directions for many people with PCOS. It's also well documented that PCOS can make weight harder to shift for hormonal reasons, not a matter of effort. A single BMI number doesn't capture any of that interaction. A waist measurement and how you actually feel day to day, energy, cycle regularity, mood, carry information a BMI number alone misses entirely.

BMI and fertility treatment

Many fertility clinics and some public or insurance-based IVF funding pathways use BMI thresholds as part of eligibility criteria. That's a policy and access fact worth knowing plainly, and it's a common reason people arrive at a BMI calculator feeling anxious rather than curious. This page won't comment on whether a given number predicts your outcome, and it has no advice about meeting a threshold; that's a conversation for your clinic.

BMI in perimenopause and postmenopause

Body composition shifts in this window even when the scale doesn't move much, muscle mass tends to decline and fat distribution tends to shift toward the abdomen. BMI can read exactly the same across that transition while quite a lot changes underneath it, which is part of why a waist measurement can be more informative during this stage than it was earlier.

Tracking these numbers is optional

If numbers like this one make food or your body harder to think about, skipping them is a legitimate choice, not a failure to engage with your health. There's no requirement to weigh in or calculate anything to take your health seriously.

Also worth a look: Want calorie and macro targets rather than a weight-and-height statistic? Try our macro calculator. And for a fuller picture of PCOS, read our complete guide to PCOS.