An ideal weight calculator can provide a useful starting estimate, but no single number defines a healthy body. This guide compares four commonly used ideal body weight formulas, shows how to calculate them with worked examples, explains the assumptions behind each method, and outlines when a clinician’s advice matters more than a chart or calculator.
Overview
The phrase “ideal weight” suggests that one precise target exists for every person of a given height. In practice, the result depends on the method used and does not account fully for muscle mass, bone structure, body-fat distribution, age, medical conditions, or personal goals. For that reason, these calculations are better understood as reference ranges or discussion points rather than prescriptions.
Several ideal body weight formulas were developed for clinical estimation, particularly when a quick weight estimate is needed from height. They are not interchangeable: each uses different constants and can produce noticeably different results. Comparing more than one formula can show the uncertainty around the estimate.
These calculations also differ from a BMI calculator. BMI compares weight with height using a population-based screening measure, while ideal body weight formulas estimate a target from height and a sex-specific equation. Neither tool can independently determine whether your weight, nutrition, or health is appropriate.
How to estimate ideal body weight
Most classic ideal body weight formulas use height in inches and begin with a baseline for the first 5 feet. To calculate your height in inches, multiply the number of feet by 12 and add the remaining inches. For example, 5 feet 4 inches is 64 inches, or 4 inches above the 5-foot baseline.
The following formulas are commonly encountered. They are presented for comparison, not as a recommendation that one is universally best.
| Formula | Male equation | Female equation |
|---|---|---|
| Devine | 50 kg + 2.3 kg for each inch over 5 feet | 45.5 kg + 2.3 kg for each inch over 5 feet |
| Robinson | 52 kg + 1.9 kg for each inch over 5 feet | 49 kg + 1.7 kg for each inch over 5 feet |
| Miller | 56.2 kg + 1.41 kg for each inch over 5 feet | 53.1 kg + 1.36 kg for each inch over 5 feet |
| Hamwi | 106 lb + 6 lb for each inch over 5 feet | 100 lb + 5 lb for each inch over 5 feet |
For heights below 5 feet, the calculation requires subtracting the relevant amount for each inch below the baseline. Because these equations are estimates, rounding to the nearest whole kilogram or pound is usually sufficient. Avoid presenting the result with false precision, such as several decimal places.
Quick height conversion chart
| Height | Approximate centimeters | Total inches |
|---|---|---|
| 5 ft 0 in | 152 cm | 60 in |
| 5 ft 2 in | 157 cm | 62 in |
| 5 ft 4 in | 163 cm | 64 in |
| 5 ft 6 in | 168 cm | 66 in |
| 5 ft 8 in | 173 cm | 68 in |
| 5 ft 10 in | 178 cm | 70 in |
| 6 ft 0 in | 183 cm | 72 in |
Inputs and assumptions
An ideal weight calculator generally needs only height and the formula selected. Some tools also ask for sex because the historical equations use different constants. This is a limitation of the formulas, not a complete account of biological diversity. If a calculator’s categories do not fit you, use the result cautiously and ask a qualified health professional which measure is appropriate.
Use a consistent height measurement when comparing results. Stand without shoes on a firm, level surface, keep your head in a neutral position, and record height in either centimeters or feet and inches before converting. Small measurement differences can change the estimate slightly, but they should not be treated as meaningful changes in health.
These formulas assume an adult and do not adjust for body composition. A person with substantial muscle mass may weigh more than an equation suggests while having good fitness and metabolic health. Conversely, a person within a calculated range may still have concerns related to nutrition, strength, blood pressure, blood glucose, or waist circumference. A BMI results guide can help explain another screening measure, but it has similar limitations.
Do not use an adult ideal body weight formula as a stand-alone target for children, adolescents, pregnancy, or people with conditions that affect fluid balance. It may also be unsuitable without professional interpretation after an amputation or in cases of significant swelling, severe illness, or a history of disordered eating. In these situations, the most useful target may be based on growth patterns, treatment goals, strength, symptoms, or laboratory results rather than a generic height formula.
Worked examples
Example 1: 5 feet 4 inches
A person who is 5 feet 4 inches tall is 64 inches, or 4 inches above 5 feet.
- Devine, female equation: 45.5 + (2.3 × 4) = 54.7 kg, or about 121 lb.
- Robinson, female equation: 49 + (1.7 × 4) = 55.8 kg, or about 123 lb.
- Miller, female equation: 53.1 + (1.36 × 4) = 58.5 kg, or about 129 lb.
- Hamwi, female equation: 100 + (5 × 4) = 120 lb, or about 54.4 kg.
These results span roughly 120 to 129 pounds. That spread illustrates why it is more responsible to discuss an estimated range than to select one “correct” number.
Example 2: 6 feet 0 inches
A person who is 6 feet tall is 72 inches, or 12 inches above 5 feet.
- Devine, male equation: 50 + (2.3 × 12) = 77.6 kg, or about 171 lb.
- Robinson, male equation: 52 + (1.9 × 12) = 74.8 kg, or about 165 lb.
- Miller, male equation: 56.2 + (1.41 × 12) = 73.1 kg, or about 161 lb.
- Hamwi, male equation: 106 + (6 × 12) = 178 lb, or about 81 kg.
Here, the estimates span approximately 161 to 178 pounds. If you are using a result to plan nutrition or weight change, consider it alongside your current weight trend, waist measurement, activity, dietary intake, and medical history. For calorie planning, a TDEE calculator addresses daily energy needs, while a macro calculator can help organize protein, carbohydrate, and fat targets.
When to recalculate
Recalculate when you discover that your original height entry was incorrect, when a clinician recommends a different formula, or when you need to compare results consistently for a specific health discussion. Height usually changes little in adulthood, so repeatedly checking an ideal weight calculator will not produce a more accurate target. For children and teenagers, height and weight should be reviewed using age- and sex-specific growth information rather than adult equations.
If your goal is weight loss or gain, reassess the plan based on progress and wellbeing rather than chasing a formula result. A gradual change in weight, stable energy, adequate nutrition, and the ability to maintain normal activities are more useful signals than reaching a single calculated number. Revisit your plan after a meaningful change in activity, medication, pregnancy status, health condition, or professional advice.
A practical clinician discussion checklist
- Bring your height, current weight, recent weight trend, and the formula results you reviewed.
- Ask whether BMI, waist measurement, body composition, or another measure is most relevant to your goal.
- Discuss medical conditions, medications, pregnancy, eating concerns, and past weight changes.
- Ask for a realistic range and the signs that should prompt a follow-up visit.
- Agree on what to monitor, such as strength, symptoms, blood pressure, nutrition, or laboratory results.
An ideal weight calculator is most useful when it supports a broader conversation, not when it replaces one. Save your height, selected formula, date, and result so future comparisons use the same assumptions. If a result causes distress or encourages restrictive eating, stop using the calculator and seek support from a healthcare professional.
