BMI for ages 55 to 59
If you are aged 55 to 59, the adult BMI bands apply to you. Here they are worked through for 5 ft 6 in and 171 lb.
How it works
BMI equals weight in kilograms over height in meters squared. The page accepts pounds and inches and converts them first. On this page 171 lb at 5 ft 6 in converts to 77.6 kg.
Worked example
For 5 ft 6 in and 171 lb, the metric values are 1.6764 m and 77.6 kg. Dividing gives 77.6 ÷ (1.6764 × 1.6764) = 77.6 ÷ 2.810 = 27.6. The result is overweight.
Common questions
What BMI range counts as a healthy weight for adults?
Under 18.5 is underweight. 18.5 to 24.9 is a healthy weight. 25 to 29.9 is overweight. 30 or more is obesity. At 5 ft 6 in, a BMI of 18.5 to 24.9 works out to 115 to 154 lb.
Does BMI measure body fat?
No. BMI only uses height and weight. Two people with the same BMI can carry very different amounts of fat and muscle. At 5 ft 6 in and 171 lb, the BMI of 27.6 comes from those two numbers alone.
Is BMI accurate for muscular people?
It can read high for someone with a lot of muscle, because muscle weighs more than the same volume of fat. A body fat measurement gives a better picture in that case. At 171 lb, the BMI of 27.6 says nothing about how much of that weight is muscle.
Does the adult BMI formula work for children and teens?
No. Children and teens are compared with others of the same age and sex. They need a percentile-based calculator instead of the adult bands. This page uses age 57 as its example, and the adult bands apply from age 20.
Does age or sex change the adult BMI result?
The number itself does not change. The formula uses only height and weight. Some health bodies suggest different cut points for some groups. Ask your doctor what suits you. At age 57 the result for 5 ft 6 in and 171 lb is 27.6, the same as at any other adult age.