Kalkulo

Ideal weight calculator

Get a reference healthy weight range in pounds from the Lorentz formula, to cross-check against BMI, waist size and body-fat percentage.

Result
144 – 159.1 lbs
Ideal range (Lorentz)

About this tool

Why use this tool

The ideal body weight calculator gives a theoretical reference range based on your height and sex. It is used clinically alongside BMI to set realistic weight goals and to calculate medication doses (e.g. anaesthesia) per NIH clinical guidelines.

How the calculation works

The Lorentz formula (metric): ideal weight(kg) = height(cm) − 100 − (height − 150) ÷ K, with K = 4 for men, K = 2.5 for women. A ±5 % range accounts for frame size and muscle mass. Alternative US clinical formulas include Devine (used for drug dosing) and Robinson.

Real example

A man 5'11" (180 cm): ideal = 180 − 100 − (180 − 150) ÷ 4 = 72.5 kg ≈ 160 lbs. Range: 152–168 lbs. A woman 5'5" (165 cm): ideal = 165 − 100 − (165 − 150) ÷ 2.5 = 59 kg ≈ 130 lbs. Range: 124–137 lbs.

Practical tips

Ideal weight is a reference, not a rigid target. Combine it with BMI (CDC healthy range 18.5–24.9), waist circumference (below 35 in for women, 40 in for men) and body fat percentage measured by DEXA scan or a trained professional. Muscular athletes may exceed ideal weight without being overfat. Follow USDA MyPlate guidance and the CDC's 150 minutes/week of moderate activity. Ask your primary care provider for a referral to a Registered Dietitian Nutritionist (RDN).

Disclaimer

This formula is a rough estimate and does not replace clinical assessment. It is not appropriate for children, adolescents (use CDC growth percentiles), pregnant women, older adults or elite athletes. Consult a healthcare provider before setting a significant weight-change goal, especially with a history of eating disorders — contact NEDA (nationaleatingdisorders.org) for support.

Frequently asked questions

How does the Lorentz formula compare to the Devine formula used for drug dosing?⌄
US clinicians dosing medication (such as anaesthesia) more commonly use the Devine formula, published in 1974, which gives results in a similar range to Lorentz for most adult heights. Both are simplified reference formulas rather than measures of actual body composition, and neither should be used to calculate a drug dose without a qualified clinician.
Why is my ideal weight range different from my BMI healthy range?⌄
The two use different math and were built for different purposes. BMI compares weight to height squared across a wide healthy band (18.5-24.9), while the Lorentz formula centres on a single reference figure adjusted by sex, then applies a percentage range around it. They usually overlap but are not designed to match exactly, so use them as complementary checks rather than expecting identical numbers.
Does this apply to a muscular athlete or bodybuilder?⌄
No formula based only on height and sex accounts for muscle mass, so a muscular athlete can weigh well above their calculated ideal weight without carrying excess body fat. For this population, body composition measurement (skinfold calipers, bioelectrical impedance or a DEXA scan) is far more informative than any height-based weight formula.
What is a more precise way to check body composition than a weight formula?⌄
A DEXA (dual-energy X-ray absorptiometry) scan is considered a clinical gold standard, breaking down weight into fat mass, lean mass and bone density. More accessible options include bioelectrical impedance scales and skinfold callipers measured by a trained professional, both of which give a body-fat percentage that a height-based formula cannot provide.
Should older adults target the same ideal weight range as younger adults?⌄
Not necessarily. Research on ageing populations suggests a BMI slightly above the standard healthy range can be protective against frailty and falls in adults over 65, so a rigid younger-adult weight target may not be the right goal. Discuss an appropriate range for your age and health status with your primary care provider rather than relying on the formula alone.

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