Ideal Weight Calculator

Read the range before the average

For a woman who is 165 cm tall, the four equations return values from roughly 56.4 to 59.8 kg. Their arithmetic average is about 57.6 kg. The adult BMI interval of 18.5-24.9 covers a much wider 50.4-67.8 kg at the same height. An ideal weight calculator can display both numbers correctly because they answer different questions.

The single value is a summary of historical height equations. The interval comes from multiplying the two adult BMI limits by height squared. If current weight is entered, the tool reports its distance from the equation average; it does not turn that distance into an instruction to gain or lose weight. That distinction matters when someone asks, “What Is My Ideal Weight?”

How the four equations were built

Hamwi starts at 106 lb for a 5-foot man and 100 lb for a 5-foot woman, then adds 6 or 5 lb for each additional inch. Devine uses 50.0 and 45.5 kg at 5 feet, adding 2.3 kg per inch for either sex. Robinson uses 52.0 and 49.0 kg with smaller increments; Miller begins higher but rises more slowly.

The labels can make the results look more personal than they are. Devine's equation appeared in a 1974 paper about gentamicin therapy. Robinson and colleagues later fitted equations to Metropolitan Life height-weight tables for use in drug-dosage calculations; this page uses the commonly cited rounded Robinson coefficients. Later research found that these linear equations drift away from BMI-based weights at the shorter and taller ends of the height spectrum. A Devine formula calculator is therefore reproducing a historical equation, not discovering a person's best weight.

The 5-foot boundary is real

The published forms use height in inches above 5 feet, equal to 152.4 cm, and clinical references commonly specify a height of at least 60 inches. Returning the same base value for every shorter person would be misleading. This implementation accepts heights from 152.4 cm upward; below that point, the adult BMI calculation or an individual assessment is more defensible than silently extending these old equations.

What the displayed average means

The average is included so the spread can be read quickly. It has not been validated as a fifth formula or a treatment target. The three Robinson bands are also plain percentages around one equation result. They do not measure wrist size, bone structure, or a “small” and “large” frame.

BMI adds context, not a diagnosis

A healthy weight calculator often uses BMI because it offers a range instead of a single point. The World Health Organization classifies 18.5-24.9 as the normal-weight range for adults. For 175 cm, those limits convert to about 56.7 and 76.3 kg. This is the source of the range shown in the result card.

BMI cannot separate muscle from fat, show where fat is distributed, or account for fluid retention and limb loss. An athlete and an adult with low muscle mass may have the same BMI while their clinical situations differ. Waist measurement, recent weight history, physical function, laboratory findings, and symptoms provide information that height and weight alone do not contain.

Age needs a different method

Ideal weight by height and age is not produced by adding age to these equations. Children and teenagers need sex- and age-specific growth charts; adult BMI cutoffs and the four formulas should not replace that assessment. In older adults, unintentional weight loss, muscle loss, frailty, and illness may matter more than closeness to a calculated point. This page deliberately has no age field because the equations do not use one.

An ideal weight chart is a BMI conversion table

The chart below shows the weight equivalent of BMI 18.5 and 24.9 at common heights. It is useful for a quick ideal weight for height lookup, but every value remains an adult screening reference. There is no midpoint column because the middle of a mathematical interval is not automatically a personal goal.

Choose the number that matches the question

An ideal body weight calculator is most useful for comparing named equations. A BMI-derived range is better when the question is simply how a particular height maps to adult screening categories. Neither tells a person how quickly to change weight, what calorie intake to choose, or whether symptoms are caused by weight.

Some clinical protocols use actual, ideal, adjusted, lean, or predicted body weight for different purposes. The correct choice depends on the drug, ventilation protocol, kidney function, and clinical setting. Do not use the value on this page to calculate or alter a medication dose. A label such as “Devine” does not make a consumer result a prescribing instruction.

For personal tracking, repeat measurements under similar conditions and look at the trend rather than one day's change. Fluid balance, salt intake, digestion, and the menstrual cycle can move scale weight without an equivalent change in body tissue. A large or unintentional change, pregnancy, edema, an eating-disorder history, or concern about growth calls for individual medical or dietetic assessment.

The result is best read as a comparison sheet: four historical equations on one side and an adult BMI conversion on the other. If the values disagree, that does not necessarily mean the calculation failed. It shows why ideal weight for height cannot be reduced to one universally correct number.