BMI for women is calculated exactly as for men — weight in kilograms divided by height in meters squared — and uses the same adult categories: 18.5 to 24.9 is a healthy weight, 25 to 29.9 overweight, and 30 or more obesity. A woman who is 5 ft 4 in and weighs 140 lb has a BMI of 24.0, a healthy weight; the healthy range at her height is 108 to 145 lb.
What differs for women is what lies behind the number. At the same BMI, women carry around 10 percentage points more body fat than men, and fat moves toward the waist after menopause. So this calculator adds an estimate of your body fat for your age and, if you enter it, a waist check.
Worked example
Height: 5 ft 4 inWeight: 150 lbAge: 45 yearsWaist: 33 in
Your BMI: 25.7 Overweight
The healthy range at 5 ft 4 in is 108 to 145 lb, so 150 lb is 5 lb over it. A 33-inch waist is a waist-to-height ratio of 0.52 — just over the 0.5 line.
Open this example in the calculator →How to use the BMI Calculator for Women
- Choose US or metric units and enter your height and weight.
- Add your age for a body-fat estimate (18 or over).
- Optionally measure your waist midway between your lowest rib and the top of your hip bone, and enter it.
- Read your BMI, healthy weight range, body-fat estimate and waist result.
Is BMI different for women?
The formula and the cut-offs are the same. The WHO and the CDC apply 18.5, 25, 30, 35 and 40 to every adult, because the health risks that BMI predicts rise along the same curve for women and men. If a site gives you a "female BMI" that differs from the standard one, it is not computing BMI.
Body composition does differ. Using the Deurenberg equation, a woman of 45 with a BMI of 25.7 has an estimated body fat of about 36%; a man of the same age and BMI, about 25%. Neither number is a diagnosis — the equation has an error of around 4 percentage points and reads muscle as fat — but it shows why the same BMI can mean different things.
Why the waist matters more for women after 40
Around menopause, falling estrogen shifts fat storage from the hips and thighs to the abdomen. BMI may stay the same while the waist grows, and it is the waist that tracks the risk of type 2 diabetes and heart disease. The WHO marks increased risk for women at a waist of 80 cm (31.5 in) and substantially increased risk at 88 cm (34.6 in). NICE's simpler rule works at any height: keep your waist to less than half your height.
Healthy weight for women by height
| Height | Healthy weight (BMI 18.5–24.9) |
|---|---|
| 4 ft 10 in | 89–119 lb |
| 5 ft 0 in | 95–127 lb |
| 5 ft 2 in | 101–136 lb |
| 5 ft 4 in | 108–145 lb |
| 5 ft 6 in | 115–154 lb |
| 5 ft 8 in | 122–164 lb |
| 5 ft 10 in | 129–173 lb |
| 6 ft 0 in | 137–183 lb |
The same ranges apply to men. The BMI chart has every height in pounds and kilograms.
BMI and pregnancy
BMI is not used during pregnancy, because the weight of the baby, placenta and extra fluid is not body fat. Doctors use your pre-pregnancy BMI to set how much weight to gain: 25 to 35 lb for a healthy BMI, less for overweight or obesity, more for underweight. The pregnancy weight gain calculator works this out week by week.
Body fat ranges for women
The American Council on Exercise groups women's body fat as: essential fat 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, and 32% or more as obese. Women need more essential fat than men for hormones and reproduction, which is why every range is higher. For a measured estimate rather than one from BMI, use the body fat calculator with a tape measure.
Frequently asked questions
What is a healthy BMI for a woman?
The same as for anyone: 18.5 to 24.9. Women of Asian background are often advised to aim for 18.5 to 22.9, because health risks rise at a lower BMI.
What is the ideal weight for a woman who is 5 ft 4 in?
A healthy weight at 5 ft 4 in is 108 to 145 lb (49 to 66 kg), which is a BMI of 18.5 to 24.9. Formulas used in medicine for "ideal body weight" give a narrower figure, about 120 to 129 lb — see the ideal weight calculator.
Does BMI change with age for women?
The adult categories do not change with age. But the body underneath does: women tend to gain fat and lose muscle with age, especially after menopause, so the same BMI means more body fat at 60 than at 25. A waist measurement shows that change when BMI does not.
Can I use a BMI calculator when pregnant?
No — BMI is not meaningful during pregnancy. Use your weight from before you were pregnant to find your pre-pregnancy BMI, which sets your recommended weight gain.
What waist size is healthy for a woman?
Less than half your height is a good rule at any height. The WHO sets increased risk at 80 cm (31.5 in) and substantially increased risk at 88 cm (34.6 in) for women of European background; lower thresholds are used for some ethnic groups.
Why is my BMI healthy but my body fat high?
BMI only uses height and weight. A woman with little muscle can have a healthy BMI and still carry a lot of body fat — sometimes called normal-weight obesity. A waist measurement or a body-fat estimate picks this up.
Sources
- Obesity and overweight (fact sheet) — World Health Organization
- Adult BMI Categories — Centers for Disease Control and Prevention
- Deurenberg P, Weststrate JA, Seidell JC. Body mass index as a measure of body fatness: age- and sex-specific prediction formulas. Br J Nutr 1991;65:105–114 — British Journal of Nutrition
- Waist circumference and waist–hip ratio: report of a WHO expert consultation — World Health Organization
- Overweight and obesity management (NG246), 2025 — National Institute for Health and Care Excellence (UK)
- Ashwell M, Gibson S. Waist-to-height ratio as an indicator of “early health risk”. BMJ Open 2016;6:e010159 — BMJ Open
- Percent Body Fat Calculator and categories — American Council on Exercise
- Institute of Medicine. Weight Gain During Pregnancy: Reexamining the Guidelines (2009) — National Academies Press
For general information only — not a diagnosis or a substitute for advice from a doctor. How we calculate.