This is the BMI calculator for women, the tool to help you calculate whether you have a healthy BMI for women, or an obese BMI. By using the BMI calculation formula, we'll provide an answer to the questions: "What is my BMI?" and "What is good BMI for women?". We will also explain in detail all of the BMI charts for women, the BMI ranges for women and explore why it is important to keep a normal BMI. So read on if you're interested in the BMI scale and learning more about the BMI charts for females. Welcome to our BMI calculator for females!

What is the BMI scale and what it measures?

Most of you reading this already know what is BMI, what it stands for and probably have some idea what a good BMI is. But for those who don't, and for the sake of 1 completeness, we will briefly explain what is BMI, how it is measured and how you can answer the question "What is my BMI?" even without this BMI calculator for females.

BMI stands for Body Mass Index and is a measurement of the relationship between two prominent body metrics: your weight and height. In particular, BMI is calculated from these two variables by the following BMI calculation formula:

BMI = weight / height²

A crucial remark about this formula is that the units you use DO matter. To discover what is a normal BMI, or establish where you place in the BMI ranges, you should always use the metric system, that is your weight in kilograms and your height in meters.

Don't worry if you live in one of the few countries that use the Imperial system, our calculator has a built-in length converter and a weight converter as you will see later.

BMI is not a definite measurement of anything health-related, but it is a good statistical measurement so we know if there is anything drastically wrong with our bodies, and if we need to worry about health problems. BMI was never designed to be a diagnostic tool and it has many flaws, which we will talk about later. However, its simplicity makes it very convenient as a first-approach tool to statistically determine if someone is underweight, or has an obese BMI, so you can start looking deeper at why that is, and if there are any health risks associated.

Normal BMI for women and why separate it from men

When it comes to health and well-being, we are all equally concerned. Why, then, do we make the distinction between men and women? The truth is that, despite all of us being equally involved in health issues, we are not the exact same physically. So when we talk about health issues it is important to make a distinction between different population groups. As you will see later, it is not only about women vs men, within each sex we also divide them further, into age groups, to obtain the best comparison possible.

In fact, here at Omni Calculator we have created 5 different BMI calculators, one for each of the four major BMI groups (children, teenagers, women, and men) as well as a general one, for good measure. If you have landed in this calculator but you are not an adult woman, here is a list of all the BMI calculators we have made with links, so that you can use the one that applies to you:

What is a good BMI for women? - WHO and BMI categories

In the year 2000, the World Health Organization (WHO) published a report called Obesity: preventing and managing the global epidemic. In page 9 of this report, there are all the BMI categories recognized by WHO and their BMI ranges. We will use this as a reference from now on. We also include other subcategories that are in agreement with WHO guidelines. These ranges can be plotted on a BMI chart for females and males. You can see the chart in the section below.

There are no distinct charts for male and female, because, amongst other reasons, BMI is just a statistical parameter and doesn't take into account the differences in body shapes and musculature between individuals or groups. Another way to look at it is that even though women tend to have higher levels of healthy body fat which would make them heavier, men also tend to have higher levels of muscle, which weighs more and contributes to balancing this effect.

Unfortunately, the reality is much more complicated than that, and this dissonance just exposes the problem of BMI when dealing with different body types. We will get into more detail about these problems, as well as discussing the validity of the values for healthy BMI for women, and how we can assess our body health better by combining BMI with other parameters.

BMI percentile and its relevance

Let's move on to the BMI percentile results you heard about, which this calculator is able to provide. Percentile is another statistical measurement closely related to the concept of percentage. One way to understand it is to think of them as percentage brackets. Technically you could have 100 different percentiles but, to make it easier for ourselves, we typically divide them in groups of more than 1%.

In this calculator, we present data in 9 percentiles, distributed as follows: 0th-5th, 5th-10th, 10th-15th, 15th-25th, 25th-50th, 50th-75th, 75th-85th, 85th-90th, 90th-95th. Each percentile tells you how you relate to the rest of the population in your group. For this calculator, we have selected the female population of the USA and divided it into age groups of ten years, as follows: 20-29, 30-39, ..., 70-79, 80+.

What the percentile value tells you is where you rank in terms of BMI for women amongst the rest of the American female population. For example, if you're in the 75th percentile, it means that 75% of the female population in the USA has a BMI similar to or than lower than yours. This is a comparative tool which means it also has its drawbacks and limitations.

So, when you're having a look at your percentile, just remember that it is skewed towards the condition of the general population. For example, in the USA women (and men) tend to be overweight, so being placed in the middle (50th) percentile is not exactly a good sign, since it probably means you're slightly overweight. Using percentiles together with absolute BMI values (or even with BMI prime for women) you give you more information about your current state.

We have just sneakily dropped a mention about BMI prime, which is a new term. Don't worry, we won't leave you hanging, let's explain it and its relevance.

BMI chart for women and BMI prime

BMI prime is a term often mentioned in BMI articles that might seem confusing at first glance. It typically ranges from 0.5 to 2, while BMI itself has values between 15 and 40. However, they are both strongly correlated. BMI prime is no more than the ratio of the actual BMI to the ideal BMI for women. The value for healthy or normal BMI for women is 25, the same as for men.

What is the advantage of the BMI prime scale over the normal BMI scale? As long as you know what it means, BMI prime will not only answer the question "What is my BMI?" but it will also answer the questions "What is good BMI?" and "Is my BMI good?" at the same time. By having a number that compares the healthy BMI for women with your actual BMI, you get double the information in just one number.

An ideal BMI prime is around 1, which corresponds to a BMI of 25. The margins are narrow, since we are talking about small numbers, so, even though 1.5 sounds like close enough to 1, it corresponds to a BMI of 37.5, which means you have "Obese Class II" or "Severly obese" according to WHO BMI categories.

Another way to compare your BMI and determine whether you have a healthy BMI, or at least a normal BMI, is to look at the BMI chart for women. Below is said BMI chart for females and males. It is conveniently color-coded to separate the regions of healthy BMI from those that are risky or dangerous.

Chart showing BMI ranges for women

To use this BMI chart please follow these steps:

  1. Find where your BMI is located in the BMI chart for women. You can either use the calculated BMI or your weight and height.
  2. With the help of the legend and the colors in the chart, assess how healthy your BMI is.
  3. If necessary, devise a plan to change your BMI to healthier levels. If it's already healthy: Congratulations!

We have mentioned that the first step is to calculate your BMI as female, and we showed you how to use the BMI calculation formula to do that by hand. However, we haven't really showed you how to use the BMI calculator for women, so let's take a closer look at that now.

How to use and interpret the BMI for women calculator

Whether you have read all the text above or have just jumped to this section to use the BMI calculator for females, we will now teach you how to operate the calculator, and how to interpret its results. First things first, let's answer the question "what is my BMI?" using our calculator:

  1. Input your height. BMI is calculated using meters, but you can use any units and the calculator will convert them for you.
  2. Input your weight. The BMI calculator for women will convert it into the right units for you.
  3. You will get the results for your BMI and BMI prime automatically, as well as your WHO BMI category. If that's all you care about, you're done.
  4. Input your age in years.
  5. Your percentile will be computed and shown. Remember this is calculated using the female population of the USA.

Now you have your results, and it's time to interpret them. Let's start with the BMI prime and BMI scales. Since they are strongly correlated, it is sufficient to look at one of them, but we show both so you can choose your favorite. Let's say you got a BMI of 29. It will show as "Overweight" with a BMI prime of 1.16.

Theoretically, this means that you have a little extra weight that you should think of getting rid of if you want to get down to your ideal weight, but, before you go rushing to start a diet, think carefully. First of all, where is that extra weight coming from? Is it body fat, lean mass or maybe it's just water in your body? Answering these questions correctly is very important and can be tricky since all components have different density. As a starting point, we recommend you use our calculators mentioned with underlined words.

Next up we need to understand the percentile you are placed in. Assuming you are 35 years old, your percentile will be shown as "75th". This means that 75% of the USA female population in the age range of 30-39 has a lower BMI than you do. This is generally an indicator of whether things are right or wrong, but as with all BMIs, it's not definitive.

Healthy BMI for women: how bad is to be in the obese BMI range?

We will now show you some data from a correlational study between the BMI for women and mortality rate. As we can see, there is a strong correlation between having a not ideal BMI for women and a high mortality rate. Does it mean that an unhealthy BMI kills? Well, we do not know for certain, since correlation doesn't imply causation but it would seem that it is much safer to have a normal BMI for women (18.5 - 25), which shouldn't come as a surprise.

Chart showing the correlation between BMI for woemn and mortality rates

What is more surprising is the strong correlation at a slightly unhealthy BMI. It could be totally possible that slightly high BMI causes a higher risk of death, but given the variations in BMI due to many different factors, there's another explanation that seems more plausible. BMI is an indicator that works both ways: women with normal BMI tend to be healthy, and healthy females tend to have normal BMI.

For example, as we age, our metabolisms degrades and it becomes much easier to put on weight than it was before. If you think about it, it's much harder to find an old person that has a healthy weight. People tend to be overweight or underweight as they grow up, compared to their younger years. In any case, it is much better to play it safe and try to stay in an ideal and healthy BMI range for women, since there's nothing to win by having extreme BMI values, and there's a lot to lose.

Differences between male and female BMI percentiles

It is time to take a look at the differences in BMI between men and women beyond the body composition that we have mentioned before. The first thing to mention is the difference in body type, not only between men and women but also within those groups. If you look at all the men in the world, their general body shape doesn't really vary that much, except for the proportion of fat and muscle.

However, if you look at women, their body shapes change dramatically, even between people with the same proportions of body fat and muscle. For example, the size of the bust, the shape, and proportion between hips and waist. Even women's legs tend to differ much more from one female to another than they do for men. What does this mean for BMI charts for women? It means a big disparity.

If we look at the BMI ranges for women, they are the same as for men because those are made in a purely theoretical way. If instead, you look at the percentile BMI ranges, the story changes a lot. The spread of BMI values in women is much greater than that of men. Let's look at an example to understand this better.

Let's compare the values for the 5th and 95th percentiles of BMI for women to those for men. There is something surprising. Across all age groups, the 5th percentile limit is lower for women than for men but, at the same time, the 95th percentile limit is also higher for women. So the distribution of BMI for women is not biased towards higher BMI or lower BMI, but it is more evenly distributed than for men.

What this means is that at the extreme values of BMI ranges, there are proportionally more women than men in those extremes. There are two possible reasons for this, and it is likely they are both at play. First of all, it could be due to the above difference in body shapes. Due to the wide range of female body type, women have a much larger range of BMIs that could still be considered healthy, whereas the range is much narrower for men.

The other possibility comes from societal pressure. It is unarguable that women are treated differently than men in our society, from gender pay gap to physical appearance. And it is this physical appearance pressure that could possibly be at the root of these extreme cases. Some women pathologically try to get an 'ideal weight' that is far too low for it to be healthy. While others might feel like this is all a big lie, and there is nothing wrong with having an obese BMI. Both approaches are seriously dangerous and are potentially life-threatening. So we need to grow, as a society, towards a more educated view of body weight where health is more important than looks and unattainable (fake) standards of beauty.

Álvaro Díez
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