BMI for Women

Body Mass Index (BMI) is a tool of measurement that can be used to categorise a woman’s weight and predict how it might affect her health.

The BMI for women is calculated the same way as the BMI for men and is a useful tool to check if a woman is within a healthy weight range or underweight, overweight, or obese.

What is a BMI?

A BMI, or body mass index, is a straightforward and commonly used screening tool that indicates body fat levels.

Your BMI is used to classify your weight category as defined by the World Health Organization (WHO). These weight categories are the same for men and women and include underweight, healthy or normal weight, overweight, and obese.

Depending on your weight category, you may be more at risk of developing certain health problems. For example, people with a very high BMI are classified as obese and may be at increased risk of high blood pressure, type II diabetes, coronary heart disease, stroke, and sleep apnoea. Similarly, people with a very low BMI are classified as underweight and may be at risk of bone density loss, anaemia, and heart problems.

However, BMI has limitations, as it does not consider a person’s gender, age, ethnicity, body fat distribution or muscle mass. BMI data, therefore, tends to be used more commonly to assess people’s weight at a population level.

How to calculate BMI for women

There are several ways you can calculate BMI for women. You can use a BMI calculator, manually work it out by using the BMI formula, or look at a BMI chart for women.

BMI formula for women

To calculate BMI for women, you just need to know their height and weight.

Using metric units, all you need to do is divide your weight in kilograms by the square of your height in metres.

BMI = Weight (kg) / Height (m)²

Once you have calculated your BMI, you can find out whether you’re classed as underweight, a healthy weight, overweight or obese, per the World Health Organisation (WHO) guidelines.

BMI calculator for women

A quick and easy way to find out your BMI would be to use a BMI calculator. Women would simply need to enter their weight and height into the online calculator to find out their BMI and associated weight category.

BMI chart for women

BMI graphs and charts are a simple and visual way to measure your BMI. To use a BMI chart, women just need to know their height and weight. The same BMI graphs, tables or charts can be used for both men and women.

BMI charts or graphs, like the one below, typically have height measurements in feet/inches and/or centimetres along the horizontal axis and weight amounts in pounds or kilograms down the vertical axis.

A BMI chart can also indicate a suitable weight range to keep within or aim for, to maintain or achieve a healthy weight BMI rating. For example, if you are a woman of average UK height at 5 foot 3 inches, you can follow this height column down on the BMI chart. When you reach the normal ‘green’ zone, you can see that you need to weigh between 105 pounds to 140 pounds to enjoy a healthy BMI rating. A woman of the same average UK height falls into the overweight BMI category if they weigh 145 to 165 pounds.

What is the ideal average BMI for a woman?

The ideal average BMI for a woman is between 18.5 and 24.9. Above this BMI, women fall into the weight categories of overweight and obese, while a BMI below 18.5 is classified as underweight.

The parameters for BMI and their weight categories are classified by the World Health Organization (WHO) as follows:

Below 18.5 - Underweight

18.5 to 24.9 - Healthy weight

25.0 to 29.9 - Overweight

30.0 and above – Obese

What should the ideal BMI for women be?

A healthy BMI for women is between 18.5 and 24.9 – this is also the same for men. However, it’s important to note that even at the same BMI, women tend to have more body fat than men.

A woman’s ethnicity and age may also impact their BMI measurements. For example, older women also tend to have lower muscle mass than younger women, which may lead to the BMI underestimating their body fat levels.

Women should also be aware that BMI is not an accurate measurement of weight or health during pregnancy and, therefore, should not be used.