Ideal Body Weight Calculator

Ideal body weight is the name of a group of formulas, not a promise of one perfect weight. Most use only height and male or female coefficients, without accounting for muscle, body frame, nutrition or medical history.

Read the BMI interval as a broad screening reference and the four historical estimates as separate calculations. Different results reflect different assumptions; averaging them would not produce a personal recommendation.

BMI is weight in kilograms divided by height in metres squared. To reverse the equation, multiply a chosen BMI by height squared. This page uses 18.5 and 24.9 as its displayed endpoints, matching the commonly printed adult reference band.

CDC defines the adult healthy-weight category as BMI 18.5 to less than 25. The 24.9 endpoint is a conventional decimal display, not a biological cliff. We use the CDC adult age threshold of 20 years; younger people need age- and sex-specific assessment.

These familiar formulas express a baseline weight at 5 feet (152.4 cm), then add weight for every additional inch. Several arose in clinical or drug-dosing contexts; this consumer tool does not apply them to any medication decision.

In the table, x is the number of inches above 5 feet, and results are in kilograms. Hamwi uses rounded kilogram coefficients; calculators that use the original pound coefficients may differ slightly. Each method is shown separately.

For an adult who is 170 cm tall, height in metres is 1.70 and height squared is 2.89. Multiplying by 18.5 gives 53.465 kg; multiplying by 24.9 gives 71.961 kg. The calculator displays that interval as about 53.5–72.0 kg.

Using the female historical coefficients, the same height is about 6.93 inches above five feet. Devine gives approximately 61.4 kg, Robinson 60.8 kg, Miller 62.5 kg and Hamwi 60.7 kg. These distinct numbers illustrate model choice; none establishes an individual treatment goal.

Measure standing height barefoot against a vertical wall or stadiometer. Keep your heels on a level floor and look straight ahead. A flat book can mark the top of your head; repeat the reading if posture or hair changes the result.

The height input accepts centimetres or total inches. For 5 ft 7 in, enter 67 inches—not 5.7. One inch is exactly 2.54 cm, and one pound is approximately 0.45359237 kg. Switching display units converts the same underlying measurement; rounding is only for readability.

• Use the same measurement conditions when comparing readings over time.
• Age determines eligibility; these formulas do not adjust the result year by year.
• Weight unit buttons change the output display between kilograms and pounds.

The historical equations start at 5 feet. There is no consistently established rule across these methods for extending them below that baseline, so subtracting a fixed amount per inch can give a poorly supported result.

Below 152.4 cm, this tool shows the BMI interval but leaves out all four historical estimates. The BMI interval has the same limits at every height; unusually short or tall adults may need more individual interpretation.

BMI cannot distinguish muscle from fat or show where fat is distributed. A strength athlete and a less muscular adult may share a height and weight while having quite different health profiles. Waist measurements, function and clinical context can add information that this tool does not contain.

Pregnancy, significant fluid retention, limb differences, frailty and some medical conditions can make ordinary weight references inappropriate or incomplete. Older adults may also need a different balance of nutrition and functional goals. Do not change eating patterns or medication doses solely because of this output.

• Not a pediatric growth or BMI-for-age assessment.
• Not a body-fat measurement, calorie prescription or diagnosis.
• Not a recommendation to reach the midpoint or any historical formula result.

First check the height, units and age. Then read the interval as a broad reference rather than a pass/fail label. A result outside it does not explain the cause, and a result inside it does not rule out health concerns.

For an individual assessment, a clinician or dietitian can review weight history, symptoms, body composition and your goals. Unintentional weight change or concerns about eating need more context than this calculation provides.