TDEE Lab
Inputs / Tape

Body composition estimate

Calculate BMI and a legacy circumference estimate for body fat, lean mass, and fat mass. Use the same tape placement each time for the cleanest trend.

Body Fat
18%

Tape-measure estimate calibrated from height, neck, and waist.

BMI 24.7

Healthy weight

Lean Mass 66kg

Estimated non-fat mass

Fat Mass 14kg

Estimated fat mass

Method Legacy tape

Not medical advice

Technical / Estimate

Decision path

INPUTS BMI CIRCUMFERENCE ESTIMATE

Assumptions

BMI is a screening measure. The body-fat result is a legacy circumference estimate, so it is best used as a repeatable trend marker, not a diagnosis.

Formula inputs

Height180cm
Weight80kg
Neck38cm
Waist86cm
Learn / Body Composition

BMI is quick. Tape estimates add context.

What BMI can and cannot tell you

BMI compares body weight to height. It is useful as a screening measure because it is fast and repeatable, but it does not directly measure muscle, fat, bone density, or health status.

How the body-fat estimate works

TDEE Lab uses a legacy circumference estimate based on height, neck, waist, and, for the female formula, hip circumference. Small tape-placement changes can move the result, so use the same method each time.

How to use the numbers

Treat the result as a baseline for tracking change over time. For nutrition targets, pair this page with the TDEE Lab TDEE calculator and adjust based on real progress.

Frequently asked questions

Is BMI a diagnosis?

No. BMI is a screening measure, not a diagnosis. It can be useful for a quick weight-to-height check, but it does not directly measure body fat, muscle, or health status.

How accurate is the body fat estimate?

The body fat result is a legacy circumference estimate based on tape measurements. It is useful as a consistent tracking method, but tape placement, hydration, and body shape can change the result.

Why does the female formula ask for hip circumference?

The selected female circumference equation uses height, neck, waist, and hip measurements. The male equation uses height, neck, and waist.