Ideal Weight Calculator
Find your ideal body weight using four established medical formulas — Hamwi, Devine, Robinson, and Miller — plus the BMI healthy weight range for your height.
The Four Ideal Weight Formulas
| Formula | Year | Men (base + per inch) | Women (base + per inch) |
|---|---|---|---|
| Hamwi | 1964 | 48.0 kg + 2.7 kg/inch | 45.5 kg + 2.2 kg/inch |
| Devine | 1974 | 50.0 kg + 2.3 kg/inch | 45.5 kg + 2.3 kg/inch |
| Robinson | 1983 | 52.0 kg + 1.9 kg/inch | 49.0 kg + 1.7 kg/inch |
| Miller | 1983 | 56.2 kg + 1.41 kg/inch | 53.1 kg + 1.36 kg/inch |
“Per inch” refers to inches above 5 feet (60 inches). Base weight applies at exactly 5 feet tall.
How the Ideal Weight Calculator Works
An ideal weight result is best treated as a reference range, not a verdict. The formulas on this page were originally built for clinical and dosing contexts, which means they can be useful for orientation but limited for judging appearance, strength, athletic build, or long-term health. The calculator is most useful when you compare several formulas, look at the BMI range, and then interpret the result beside body composition, waist measurement, training history, and health markers.
Core method
Ideal body weight formulas estimate a reference weight from height and sex, then compare that point estimate with the wider BMI healthy-weight range.
Worked Example
A 5 ft 8 in adult uses the calculator to compare formula estimates before setting a weight-loss target.
| Step | Value | Why it matters |
|---|---|---|
| Height | 68 inches total | Ideal weight formulas use inches above 5 feet, so this is 8 extra inches. |
| Formula comparison | Hamwi, Devine, Robinson, Miller | The calculator shows all four because no single formula is universally correct. |
| BMI range | Healthy range is wider than one formula number | This helps prevent treating one point estimate as the only acceptable weight. |
| Interpretation | Use the average as a planning reference | Body fat, muscle, waist size, and clinical markers matter more than matching one formula exactly. |
If the formula average is far below your current weight, do not treat it as an immediate target. A first goal might be 5-10% weight loss, improved waist measurement, better blood pressure, or better training consistency. If you are muscular, athletic, pregnant, growing, older, or managing a condition, the ideal-weight number can be especially incomplete.
Who Should Use This Calculator?
Weight-loss goal setting
Use ideal weight as one reference when deciding whether a goal weight is realistic, but pair it with calorie needs, body fat percentage, and a sustainable timeline.
Clinical orientation
Some medical contexts use ideal body weight for dosing or nutrition estimates. For personal decisions, clinician instructions should override a web calculator.
Comparing formulas
When formulas disagree, the spread itself is useful. A wide spread means the output should be interpreted conservatively.
Avoiding scale tunnel vision
The result should not replace waist measurements, strength, energy, lab markers, or body composition trends.
How to Interpret Your Result
| Result or situation | What it means | Next step |
|---|---|---|
| Formula average is inside BMI range | The estimates broadly agree. | Use the number as a loose reference, not a strict target. |
| Current weight is above formula average | This may reflect fat mass, muscle mass, frame size, or normal variation. | Check waist, body fat, blood pressure, and trend data. |
| Current weight is below formula average | The formula may not fit your frame, age, or clinical context. | Avoid intentional weight loss without professional guidance. |
| Athletic build | Muscle can push scale weight above formula estimates. | Use body fat and performance markers instead of IBW alone. |
Common Mistakes
- Treating ideal weight as the only healthy weight instead of one historical estimate.
- Ignoring muscle mass, frame size, ethnicity, age, pregnancy status, and health history.
- Using the result to justify aggressive dieting when a smaller first milestone would be safer and easier to maintain.
- Comparing two people of the same height without considering body composition and training history.
- Forgetting that BMI range, waist circumference, labs, symptoms, and clinician guidance may matter more.
Limitations
- Ideal body weight formulas do not measure body fat, muscle, bone density, or visceral fat.
- They were developed from older population assumptions and may not fit every body type.
- They should not be used to diagnose obesity, malnutrition, eating disorders, or metabolic health.
- Pregnancy, edema, amputation, bodybuilding, and medical fluid shifts can make the result misleading.
- Children and teens need growth-chart based assessment rather than adult IBW formulas.
Accuracy, Tracking, and Review Cadence
The best way to use a calculator is to treat the first result as a structured estimate, then compare it with real-world feedback. A number can be mathematically correct and still need adjustment for your routine, body composition, training phase, appetite, recovery, medical context, or measurement habits. For that reason, the output should start the decision rather than end it.
Review your ideal weight result when one of the assumptions changes. That might mean a meaningful weight change, a new training block, a change in job activity, a diet phase, hotter weather, medication changes, injury, illness, pregnancy, a new supplement routine, or a different measurement method. Recalculating too often creates noise, but never recalculating can leave you following an old number that no longer matches your situation.
| Review trigger | Why it matters | Practical response |
|---|---|---|
| Body or activity changes | Most formulas depend on size, workload, or repeated behavior. | Recalculate after a stable change, not after one unusual day. |
| Goal changes | Maintenance, fat loss, performance, and recovery can require different targets. | Choose the calculator or range that matches the current goal. |
| Unexpected symptoms | Dizziness, pain, severe fatigue, dehydration, or GI issues can signal a mismatch. | Pause aggressive changes and get qualified guidance when symptoms persist. |
| Trend mismatch | The estimate may not match your actual response. | Adjust gradually and keep the measurement method consistent. |
For SEO and usability, this matters because calculator pages should not only return a number. A strong calculator page explains the formula, shows a worked example, gives interpretation rules, identifies common mistakes, and tells the user when the estimate is not enough. That context helps readers make safer decisions and reduces the chance that a precise-looking output is used outside its limits.
If you save the result, also save the inputs that produced it. A screenshot or note with body weight, units, activity level, goal, measurement method, date, and any unusual circumstances makes future comparisons more meaningful. Without the inputs, two results can look different even when the real change was simply a different assumption.
For best results, make one adjustment at a time. If you change the target, tracking method, training plan, food choices, and supplement routine together, it becomes difficult to know which change produced the outcome. A slower review loop usually creates better decisions.
What to Do After You Calculate ideal weight
Use the result as a decision aid, then validate it against repeatable behavior. A calculator can organize the starting assumptions, but the most important feedback comes from trend data, symptoms, training quality, appetite, energy, and whether the plan is realistic enough to repeat. If the result affects medication, medical nutrition therapy, pregnancy, kidney function, heart health, injury risk, or aggressive dieting, get individualized guidance before making large changes.
Frequently Asked Questions
What is ideal body weight?
Ideal Body Weight (IBW) is a target weight based on height and sex, originally developed for clinical drug dosing. The most common formulas (Hamwi, Devine, Robinson, Miller) were created between the 1960s and 1980s. These formulas produce a range of values — none is universally 'correct.' They should be understood as reference points rather than prescriptive targets, as they don't account for muscle mass, body composition, or individual health factors.
Which ideal weight formula is most accurate?
None of the four formulas (Hamwi, Devine, Robinson, Miller) is consistently more accurate than the others. They were all developed before modern body composition methods and are primarily used in clinical settings for drug dosing (particularly for medications with narrow therapeutic windows). For personal health goals, the BMI healthy weight range (18.5–24.9) or body fat percentage targets are more meaningful guides than IBW formulas.
Is ideal body weight the same as healthy weight?
Not exactly. IBW formulas give a single point estimate for a given height, while 'healthy weight' covers a range (BMI 18.5–24.9). A person can be healthy at weights above or below the IBW estimate. More importantly, IBW doesn't account for muscle mass — a muscular athlete may be above their IBW while having an excellent body composition. Use IBW as one data point among several, not an absolute target.
Can I be healthy above my ideal body weight?
Yes. Many people are in excellent health at weights above standard IBW estimates, particularly if they have higher muscle mass. Conversely, being at a 'normal' BMI or IBW doesn't guarantee good health if body fat distribution (visceral fat) is unfavourable. Metabolic health markers (blood pressure, blood glucose, cholesterol) are more direct indicators of health than weight alone.