Body Composition calculators

BMI does not distinguish muscle from fat. So it can misclassify very muscular people as overweight and underestimate risk in people with low muscle mass. It is a population-level screening tool, useful for tracking trends in one person over time, not a diagnosis for an individual.

Circumference-based methods, skinfold calipers, bioelectrical impedance and DEXA scans all measure different proxies and carry different error margins. Use one method consistently and track the trend , not comparing an absolute number across methods.

Ranges differ by sex, age and source, and 'healthy' athletic ranges sit lower than general population ranges. There is no single correct number. A qualified professional can interpret a result against your specific health context.

It captures where fat is carried, which BMI does not. Central fat carries different health associations than fat elsewhere. Neither measure alone is complete. Clinicians often use several together.

It is reasonably consistent when the same person measures the same way each time, which makes it useful for tracking change. Small measurement errors matter less for a trend than for a single absolute reading.

No: the first trimester typically adds very little weight, with most of the recommended gain arriving in the second and third trimesters. A simple weeks-to-date proration is a rough guide, not what a real trimester-by-trimester curve looks like.

Ranges are population guidance from pre-pregnancy BMI category. Individual factors, multiples, medical conditions, starting nutrition status, can make a different pattern appropriate. Discuss any concern with your OB-GYN or midwife instead of adjusting intake based on a calculator alone.

No. Recommended gain is higher for multiple pregnancies and is not modeled here. Use your care provider's guidance for a multiple pregnancy.

No. A weight below the healthy range carries its own risks, and weight alone does not show muscle, bone or where fat sits. Use the range as a screen, and ask a clinician what suits you.

The 18.5 to 24.9 range applies to adults. Children and teens are read against age and sex percentiles instead, and some clinicians judge the range differently for older adults. A doctor can say which applies to you.

Weekly or monthly is enough for most trends. Daily weight swings by a pound or more from water, food and salt, so one day says little. Measure at the same time of day under the same conditions.

Height is the only input. People of the same height differ in frame, muscle and fat, so a fair guideline has to leave room. The width of the range shows the uncertainty instead of hiding it.

It is a screening tool that ignores muscle, age and where fat sits, so it can mislead for athletes and older adults.

From body measurements in a formula such as the US Navy method, which is convenient but can be off by several percentage points.

By adding 280 days to the first day of the last menstrual period, or adjusting from the conception date, and only about 5% of babies arrive on that day.