BMI 6 ft 3 in 90 lbs 20 years female- severely underweight

BMI Calculator English System

Detailed info about your BMI

What is BMI?

BMI is a person's weight in kilograms divided by his/her height in meters squared. For most people, BMI is a good predictor of health problems that are linked to excess weight. BMI is also known as Quetelet’s index.

BMI is a way to discover if you are overweight, obese, underweight or normal. This calculator computes appropriately your BMI by using a "redefined overweight and obese BMI thresholds for different gender and age groups", a 2015^[1] study, for people who are more than 16 years old male or female.

Some research studies have shown that a weight loss of 1 to 2 pounds per week for six months can improve the health of overweight people. The goal of weight loss should be to improve health. You should avoid rapid weight loss, swings in weight, and improper dieting.

BMI is solely based on weight and height, so it may be an imprecise indicator (might come out as overweight) of body fat if someone has a large bone structure, athletic build or a large muscle mass. On the other hand, someone with a light bone structure might be considered of normal weight, even if they have excess body fat.

Although some factors like, bone structure and muscle mass are not part of the equation when IMC is calculated, Body Mass Index can be helpful to set limits such as underweight, normal or obese, for individuals who lead a sedentary or "normal" life. Furthermore, our BMI calculator is better than the standard BMI calculator once it includes both sex and age into its algorithm.

How to calculate your BMI?

Here is the BMI formula in the English (Avoirdupois) system where weight is in pounds, and height is in inches:

BMI = 703 x (^weight/_(height)²)

For example:

If your height is 75 inches and you weigh 90 pounds, your BMI is

BMI = 703 x (⁹⁰/_75²), or

BMI = 703 x (⁹⁰/₅₆₂₅), or

BMI = 703 x 0.016

Finally, BMI = 11.2 kg/m² (rounded).

What is BMI Prime?

BMI Prime^[3] (abbreviated BMI’) is an index of total body fat content. It is a simple modification of the familiar Body Mass Index (BMI) system.

BMI Prime is defined as the ratio of a person’s Actual Weight (or Mass) to his Upper Weight (or Mass) Limit of the “healthy weight” range. Here is the BMI Prime formula:

BMI' = ^{Actual Weight}/_{Upper Weight Limit}

Note that, in our BMI calculator, the 'Upper Weight Limit' depends on age and sex, so it is not fixed as in other calculators.

Standard BMI Chart

This table defines BMI ranges (Categories). This standard is still widely used nowadays mainly to compare populations in health related studies.

BMI	Weight Status
9.0 to 18.5	underweight
18.6 to 24.9	normal
25.0 29.9	overweight
30.0 and Above	Obese

Modified BMI Chart

The standard BMI, as defined, for example, by the World Health Organization, WHO and USDA (United States Department of Agriculture), has been frequently criticised as having various deficiencies as a measure of body fat. But this 2015 study published by the The National Center for Biotechnology Information (NCBI) made some adjustments on BMI limits to reflect the changes in body composition that occur with age like: reduced muscle mass and increased adiposity. This means that our BMI is not the same across different age groups and gender because these factors are included in our algorithm. The BMI table below, combined with the standard (WHO) BMI table, are used by our BMI Calculator to redefine the BMI classes limits.

Redefined overweight and obese BMI thresholds table

	Male		Female
Age (years)	Overweight	Obese	Overweight	Obese
16–29	28	33	27	32
30–39	27	32	27	32
40–49	25	30	25	30
50–59	24	29	24	29
60–69	24	29	25	30
70–79	25	30	26	31
80+	25	30	26	31

Important note on BMI web tools

This calculator is not meant to serve as a source of clinical guidance. BMI is only an indicator of body fatness. It also doesn't apply if you have an athletic/muscular build because muscle weighs more than fat. Be carefull. Do not use this tool calculating BMI for children Do not take any important decision about your health based on this or on any other web tool. Any questions about weight loss or changes to your diet should be discussed with your nutritionist or doctor for a personalized estimation.