Breaking Down BMI: What It Is, How To Measure It, and Whether It Really Matters

When it comes to phrases people throw around without always knowing exactly what they mean, “BMI” is high on our list (along with “clear your cache” when you’re having computer trouble.) Most of us know the tiny acronym—which stands for Body Mass Index—has something to do with our weight, but we’re not sure what. Furthermore, we know it’s meant to be calculated, but have no clue how.

what is BMI

Read on for everything you need to know about BMI.
Photo: Getty

Of course, in today’s instant-gratification age, it’s totally possible to Google it, and within seconds measure it via a handy virtual calculator, but that still doesn’t really explain what it is. That said, we decided to answer the mysterious “what is BMI” question: What it really means, how to measure it, and if it truly matters to our overall health. Read on and educate yourself!

1. What is BMI?
Essentially, body mass index is a number that’s calculated from a person’s weight and height, and it’s a pretty solid indicator of how much body fat you have.

2. To measure your BMI, you’ll need to know your height in inches.

5’0 (60 inches)
5’1 (61 inches)
5’2 (62 inches)
5’3 (63 inches)
5’4 (64 inches)
5’5 (65 inches)
5’6 (66 inches)
5’7 (67 inches)
5’8 (68 inches)
5’9 (69 inches)
5’10 (70 inches)
5’11 (71 inches)
6’0 (72 inches)
6’1 (73 inches)
6’2 (74 inches)
6’3 (75 inches)

3. Bust out the calculator: Here’s how to measure your BMI.

  • Multiply your height in inches by your height in inches.
  • Divide your weight by the number you arrived at in Step 1
  • Multiply the number you came up with in Step 2 by 705.
  • The result is your BMI.

4. What does your BMI number mean? The below is from The National Institutes of Health:

  • BMI of 19 or below: You’re considered underweight.
  • BMI between 19 and 24.9: You’re in the healthy range.
  • BMI between 25 and 29.9: You’re considered overweight.
  • BMI of 30 or greater: You’re considered obese.

People with a BMI of 25 or above are sometimes said to be at a higher risk for health problems like like heart disease, stroke, hypertension, diabetes, and cancer, although—as the Center for Disease Control and Prevention points out—BMI should be used as a screening tool to identify possible weight problems for adults, not as a diagnostic tool.

That means people with high BMIs should use the number as a jumping off point to determine if excess weight is a health risk by having a doctor perform further assessments like thick skinfold ness measurements, as well as diet, exercise, family history evaluations.