Geriatric BMI Calculator

By Joanna Michałowska, PhD candidate
Last updated: Feb 06, 2021

This geriatric BMI calculator is a tool created for adults who are over 65 years of age. Based on your height and weight, it will calculate your BMI and determine if you are underweight, overweight, or a healthy weight. Read the article below to find out why is BMI not accurate for the elderly and what are the healthy ranges for BMI for seniors.

Are you under 65 years of age, meaning that the BMI calculator for the elderly is not suitable for you? Check our BMI calculators collection and find the one that is right for you:

Why is BMI not accurate for elderly?

Body mass index (BMI) is a value calculated from the weight and height of a person. BMI over 25 is associated with with higher all-cause mortality and increased risk of suffering from various diseases, including cardiovascular disease and diabetes. Therefore, the normal ranges for BMI have been worked out to be between 18.5 and 25 kg/m².

Although BMI can be used on most adults, it does have some limitations:

  • It may overestimate body fat in athletes and people who have a muscular build; and
  • It may underestimate body fat in older persons and people who do not have a lot of muscle tissue.

Moreover, recent research showed that for older populations, being overweight is not associated with an increased risk of mortality. Therefore, different ranges for healthy BMI were found. Check the paragraphs below to find out more about BMI for seniors.

BMI for older adults - geriatric BMI guidelines

We hope that we answered the question "Why is BMI not accurate for elderly?", but who do we classify as "the elderly" in the first place? According to WHO, an older person is someone who is 65+ years old (sometimes 60+). Based on extensive research, different BMI categories were set for older adults, where healthy weight was defined as a BMI ranging from 23 to 29.9 kg/m². This stems from the fact that researchers noticed that a BMI below 23 and above 33 is associated with a significantly increased risk of mortality.

But why are geriatric BMI guidelines are different from general population? Human bodies change with age - an older person has more fatty tissue than a younger individual. Moreover, a higher BMI is associated with greater energy stores and a better nutritional state overall. This is really important when serious chronic health conditions (usually associated with age) are developed, e.g. chronic heart failure or cancer cachexia.

BMI chart for elderly

Below, we present a BMI chart for seniors together with a regular BMI chart.

  1. BMI chart for seniors.
BMI Weight status
<23 kg/m² Underweight
23-29.9 kg/m² Normal weight
>= 30 kg/m² Overweight/obese

  1. BMI chart for the general population.
BMI Weight status
<18.5 kg/m² Underweight
18.5-24.9 kg/m² Normal weight
24.9-29.9 kg/m² Overweight
>=30 kg/m² Obese

Geriatric BMI calculator

How does the geriatric BMI calculator work?

  1. It calculates BMI from the regular equation showed below:

BMI = weight [kg] / height² [m²]

  • Don't worry about the units! Our geriatric BMI calculator has a built in weight and length converter, so you can use either the metric or imperial system.
  1. Once BMI is calculated, a BMI category for the elderly is assigned.

Let's use a practical example to make sure that everything is clear. We will calculate BMI for 70-year-old Audrey who is 162 cm tall and weighs 70 kilograms.

BMI = weight [kg] / height² [m²]

BMI = 70/ 1.62²

BMI = 70/ 2.6244

BMI = 26.7

Our BMI calculator for seniors displays the result according to categories for BMI for seniors: Audrey has a healthy weight.


Joanna Michałowska, PhD candidate
Results interpretation:
BMIWeight status
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