Question 1

Which ideal-weight formula is the best?

Accepted Answer

There is no perfect formula, but the BMI healthy-weight range (BMI 18.5–24.9) is the best-supported reference today — which is why we show it as the recommended value. It gives a range instead of a single number, reflecting that there is no single "correct" weight. Broca and Devine are older formulas that output a single figure and ignore build and muscle mass. They are useful as a rough rule of thumb and for comparison, but less meaningful.

Question 2

How does the Broca formula work?

Accepted Answer

The Broca formula first sets normal weight as height in centimetres minus 100. At 175 cm that is 75 kg. The "ideal weight" lies below that: about 10% less for men, about 15% less for women. The formula dates from the 19th century, is easy to calculate but very imprecise — it ignores build, age and muscle share and gives unrealistic values for very tall or short people. We list it for comparison only.

Question 3

What is the Devine formula?

Accepted Answer

The Devine formula was originally developed in 1974 for drug dosing, not as a beauty ideal. It calculates 50 kg plus 2.3 kg per inch over 152 cm (5 feet) for men, and 45.5 kg as the base value for women. Because it builds on a fixed reference height, it gives less plausible values for very tall or short people. It is still common in medicine; as a personal weight goal it should be viewed with caution.

Question 4

How accurate is the US Navy body fat formula?

Accepted Answer

The US Navy formula (also the Hodgdon-Beckett method) estimates body fat from waist, neck, height and, for women, the hip as well. It is remarkably practical because you only need a tape measure, but typically deviates by around 3–4 percentage points from reference methods such as DEXA. Clean measuring is key: measure loosely without pulling tight, in the morning and always at the same spot. It works well for trends over time, less so for one exact figure.

Question 5

Is my body fat too high or too low?

Accepted Answer

Healthy ranges differ markedly between the sexes, because women physiologically need more essential fat. Rough guidance: for men about 10–20% is a good range, for women about 18–28%. Very low values are not automatically "better" — essential fat is vital. The calculator sorts your value into categories from "essential" to "elevated". These figures are reference points, not a diagnosis; if unsure, a medical assessment helps.

Question 6

Why does the result differ from the BMI calculator?

Accepted Answer

The BMI only relates weight to height and says nothing about body composition. This calculator goes further: it compares several ideal-weight formulas and additionally estimates your body fat from circumference measurements. Two people with an identical BMI can have very different body fat levels — for example a muscular person versus an untrained one. That is why body fat is often more meaningful than weight alone. For the classic BMI value, use our separate BMI calculator.

Question 7

Is there even a "correct" ideal weight?

Accepted Answer

No — strictly speaking, not. "Ideal weight" is an individual range, not a fixed point, and certainly not a medical requirement. Health depends on many factors: muscle mass, fitness, blood values, sleep, mental wellbeing. Two people of the same height can both be healthy at different weights. Use this calculator's figures as rough guidance, not a target. If your weight or eating behaviour is troubling you, a conversation with a doctor is a better path than a formula.

Question 8

How do I measure waist, neck and hip correctly?

Accepted Answer

Use a flexible tape and measure on bare skin without pulling tight. Measure the neck just below the larynx, with the tape tilted slightly forward. Measure the waist at navel level with a relaxed abdomen, at the end of a normal exhale. Take the hip circumference (for women) at the widest point of the buttocks. Measure in the morning if possible and repeat each measurement two or three times to avoid reading errors. Consistency matters more than the single centimetre.

Guide: Ideal Weight & Body Fat Calculator

Calculating Ideal Weight: Which Formula Is Actually Right?

Broca, Devine and BMI: The Ideal-Weight Formulas Compared

Measuring Body Fat: Methods From Caliper to Navy Formula

The US Navy Method for Body Fat Measurement Explained

Realistic Weight Loss: Why the Scale Doesn't Tell the Whole Story

You might also find useful

BMI Calculator

Calorie Calculator

Macronutrient Calculator