What should you actually weigh? Bathroom scales, BMI charts, and workout apps all answer that question differently, and most of them are built around a single number that ignores how height, sex, and frame change what a healthy body looks like. This ideal weight calculator uses the Devine formula — the same equation anesthesiologists and pharmacists have used since 1974 to dose medicine by body size — to give you a realistic target weight in both pounds and kilograms, plus a healthy range around it.
Type in your height, choose your sex, and (optionally) add your current weight. The result card updates instantly and shows how far you are from the target, so you can plan a realistic range instead of chasing a single number on a scale.
How to Use
- Choose your Sex — male or female. The Devine formula starts from a different base weight for each, so this matters more than you might expect.
- Enter your Height (feet) — the whole-foot part of your height, for example
5if you are five feet tall. - Enter your Height (inches) — the remaining inches, from
0to11. A 5′9″ person enters feet5and inches9. - Optionally type your Current Weight in pounds. Leave it blank if you only want the target; filling it in adds a "difference" line showing how much you are above or below the ideal.
- Read the result card: the ideal weight in kilograms and pounds, the ±10% healthy range, and — if you entered your current weight — the gap between where you are and where the formula thinks you should be.
The result is a starting point, not a verdict. Two people the same height and sex can carry healthy bodies that differ by 15 pounds or more depending on muscle, bone structure, and where they carry fat.
The Devine Formula Explained
Developed by B.J. Devine in the 1970s for drug dosing, the equation is deliberately simple:
- Men: ideal weight (kg) = 50 + 2.3 × (inches of height above 5 feet)
- Women: ideal weight (kg) = 45.5 + 2.3 × (inches of height above 5 feet)
In plain English: a 5-foot-tall man targets 50 kg (about 110 lb) and a 5-foot-tall woman targets 45.5 kg (about 100 lb), and every extra inch adds roughly 2.3 kg (about 5 lb). Because the formula is linear, taller people gain a little more, which is why a 6-foot man's ideal is about 77.6 kg (171 lb) rather than the same 110 lb.
The "healthy range" shown on the result card is ±10% around the ideal. That band matches how clinicians actually talk about weight: landing within roughly 10% of the Devine number usually lines up with a BMI between 18.5 and 24.9, the range most guidelines consider healthy.
How Ideal Weight Differs From BMI
BMI divides your weight by your height squared, which is useful for population statistics but clumsy for one person. A muscular athlete can have a "high" BMI while carrying almost no body fat, and a small-framed adult can sit at a "normal" BMI while carrying more fat than is comfortable.
Ideal weight from the Devine formula is a height-based target, not a body-fat measurement. Use it to set a reasonable destination, then pair it with waist circumference, energy levels, and blood work to judge whether your plan is actually working.
Examples
Example 1 — An average-height man. A 30-year-old man who is 5′9″ (69 inches) enters male, feet 5, inches 9. The calculator computes 50 + 2.3 × 9 = 70.7 kg (155.9 lb), with a healthy range of 63.6–77.8 kg. If he currently weighs 180 lb, the difference line shows about +24 lb above the ideal — a realistic 10% loss goal, not a crash diet.
Example 2 — An average-height woman. A woman who is 5′4″ (64 inches) enters female, feet 5, inches 4. The result is 45.5 + 2.3 × 4 = 54.7 kg (120.6 lb), spanning about 49–60 kg. At 132 lb she is roughly 10% above target — inside the upper edge of the healthy range, where most doctors would focus on habits rather than a strict diet.
Example 3 — Tall frame. A 6′0″ man enters feet 6, inches 0. The formula gives 50 + 2.3 × 12 = 77.6 kg (171.1 lb). Notice how much higher the target sits than the common "150 lb" rule of thumb: tall adults are supposed to weigh more, and the calculator reflects that instead of applying a one-size number.
FAQ
What is a healthy weight for my height?
For most adults, a healthy weight sits within about ±10% of the Devine ideal for your height and sex. This calculator shows that exact range in kilograms, and the matching pounds figure. At 5′9″ a man's target is near 156 lb; at 5′4″ a woman's target is near 121 lb.
How is ideal weight calculated?
The Devine formula adds 2.3 kg for every inch above 5 feet to a base of 50 kg for men and 45.5 kg for women. The result is converted to pounds by multiplying kilograms by 2.20462. This page uses that exact formula.
Is the Devine formula accurate?
It is the most widely used clinical estimate, originally built for medication dosing, not aesthetics. It is accurate as a rough target band — roughly matching a healthy BMI of 18.5–24.9 — but it does not account for muscle mass, frame size, or age, so treat the single number as a center point and the ±10% range as the real answer.
What is a good weight for a 5′6″ woman?
Using the formula: 45.5 + 2.3 × 6 = 59.3 kg, about 131 lb, with a healthy span of roughly 118–144 lb. Anything inside that band is consistent with a normal BMI; going below it quickly pushes BMI under 18.5.
What is a good weight for a 6′0″ man?
Using the formula: 50 + 2.3 × 12 = 77.6 kg, about 171 lb, with a healthy span of roughly 154–188 lb. Taller frames naturally carry more weight, and the target rises with height rather than staying fixed.
Should men and women have different ideal weights?
Yes. The Devine equation starts from 50 kg for men and 45.5 kg for women because average body composition differs. The per-inch step (2.3 kg) is the same for both, so the gap stays constant at about 4.5 lb across heights.
Can I use this calculator to lose or gain weight?
You can use it to set a realistic destination. The safe rate of change is about 0.5–1% of body weight per week; much faster usually rebounds. Pair the target with a balanced diet, regular movement, and — especially if you are far from the range — a conversation with a doctor or registered dietitian.
Disclaimer
This ideal weight calculator is provided for informational purposes only. It is not medical advice, diagnosis, or a treatment plan, and it should not replace the judgment of a qualified healthcare professional. Ideal weight is an estimate derived from height and sex alone; individual healthy weight varies with muscle, bone structure, age, ethnicity, and medical history. Always consult your doctor or a registered dietitian before starting, changing, or stopping any weight-related program.