⚖️ Ideal Weight Calculator
Estimate your ideal weight using multiple published formulas (Devine, Robinson, Miller, Hamwi). Supports metric & imperial units and provides an averaged recommended range.
What is "ideal weight" and why it matters
"Ideal weight" is a historical and clinical concept intended to give a target or reference for body mass that often correlates with lower risks for some health outcomes. Unlike Body Mass Index (BMI), which relates weight to height using a single index, ideal-weight formulas generate a specific target weight (or small range) for a given height and sometimes sex. Clinicians and researchers have used these targets for drug dosing, nutritional assessment, and population comparisons. However, ideal weight is not an absolute prescription — it is a guide that must be interpreted with an individual's body composition, muscle mass, ethnicity, age, and personal goals in mind.
Four widely used formulas
Several formulas developed in the 20th century are commonly used to estimate an “ideal” or “reference” weight. Each uses height as its primary input and differs slightly by constants and adjustments:
Devine formula (1974)
Originally proposed for calculating drug dosing in obese patients, the Devine formula is simple and widely used:
- Men: 50.0 kg + 2.3 kg for each inch over 5 feet
- Women: 45.5 kg + 2.3 kg for each inch over 5 feet
Robinson formula (1983)
The Robinson formula adjusts the Devine constants slightly and is often quoted in clinical references:
- Men: 52 kg + 1.9 kg/inch over 5 feet
- Women: 49 kg + 1.7 kg/inch over 5 feet
Miller formula (1983)
Miller uses slightly smaller increments and often yields lower ideal weights for taller individuals:
- Men: 56.2 kg + 1.41 kg/inch over 5 feet
- Women: 53.1 kg + 1.36 kg/inch over 5 feet
Hamwi formula (1964)
One of the oldest rules of thumb, Hamwi provides a compact reference:
- Men: 48.0 kg + 2.7 kg/inch over 5 feet
- Women: 45.5 kg + 2.2 kg/inch over 5 feet
How formulas differ and why we show several
Each formula was derived from different populations and clinical needs; therefore they produce slightly different numbers. Presenting multiple formulas gives users a range and prevents overreliance on a single arbitrary target. Averaging the outputs often provides a reasonable middle ground. Importantly, these formulas do not measure body composition — a person with high muscle mass may be heavier than an "ideal" number yet perfectly healthy.
Converting units and using the calculator
This calculator accepts metric (cm) or imperial (total inches) height inputs. If you prefer entering feet and inches, first convert to total inches (feet × 12 + inches). The page will compute each formula, display the results in kilograms and pounds, and show an averaged recommended range. Use the CSV download if you need to save or compare targets.
Practical example
For a 5'8" (68 in) person the Devine formula gives: (male) 50 + (2.3 × 8) = 68.4 kg. Robinson, Miller and Hamwi will give slightly different values; averaging them produces a recommended central value and a small range around it. This helps clinicians and users pick a starting point — the final target should consider muscle mass, fitness goals, and metabolic health.
Limitations and considerations
Ideal weight formulas are blunt instruments. They do not account for bone density, ethnic differences, or age-related changes in muscle mass. For elderly individuals, focusing on functional strength and lean mass retention is often more important than matching a particular number. For athletes, interpret ideal-weight estimates with caution — performance and body composition measures (body fat percentage, lean mass) are more informative.
When to use ideal weight versus BMI or body composition
Use ideal-weight estimates when you need a simple, height-based target — for example, initial clinical dosing or rough goal-setting. Use BMI for population-level screening and tracking, and body-composition measures when you need precision about fat vs lean mass. All three tools are complementary.
Choosing a target: average, range, and personalization
Since Devine, Robinson, Miller and Hamwi were developed using different samples and methods, they produce slightly different "ideal" weights for the same person. Instead of treating any single formula as an absolute, a sensible approach is to look at the spread (minimum to maximum) and the arithmetic average. The average gives a practical central target and the spread indicates reasonable flexibility. For many users the average is a helpful starting point, then you personalize based on body composition, fitness goals, and health context.
How to interpret the results
When you view the calculator output you’ll see each formula’s value (kg and lb), an average, and the min/max range. If your current weight sits comfortably within that range and you feel strong, mobile, and metabolically healthy, aggressive changes aren’t necessary. If your current weight is outside the range and you're aiming to change it, prioritize gradual adjustments, preserve lean mass with strength training and sufficient protein, and track progress using strength and functional metrics as well as weight.
Formula strengths and clinical uses
- Devine: popular for drug dosing and common in clinical references. Simple and widely applied. - Robinson: slight modification of Devine; sometimes preferred in nutrition references. - Miller: tends to yield slightly lower values for taller people; useful when a more conservative estimate is wanted. - Hamwi: older but widely cited; helpful as one of multiple comparisons.
Body composition vs. ideal weight targets
Remember that ideal-weight formulas don’t measure fat vs. muscle. Two people at the same height may have different healthy weights depending on lean mass. If you have access to body composition testing (DEXA, air-displacement plethysmography, professionally interpreted BIA), use those results to refine targets: aim for a healthy body fat percentage while maintaining or increasing lean mass.
Height below 5 feet or very tall heights
These formulas use "inches over 5 feet" as the core structure. For heights shorter than 5 feet the math still works (the "inches over 5 ft" becomes negative), but clinical judgment is important: in very short or very tall individuals body proportions differ and some formulas may be less accurate. Treat outputs as guides, not rules.
Age, sex, and life stage
Age influences body composition: older adults often lose lean mass and may benefit from targets prioritizing strength and function rather than strictly meeting a formula number. The formulas include sex-specific constants because average body composition differs between males and females, but they don’t capture individual variation—for example, a female athlete may have more lean mass than the formula anticipates.
Using ideal weight with other metrics
Combine ideal-weight outputs with BMI for population screening and with waist circumference and functional measures for risk and performance. For example, waist circumference helps detect central adiposity; functional tests (e.g., timed up-and-go, grip strength) help indicate whether weight supports mobility and independence in older adults.
Practical plan if you want to change weight
If you decide to gain or lose weight toward an ideal range, set realistic, slow, and sustainable plans: 0.25–0.75% body mass per week for many people when losing; 200–400 kcal/day surplus with resistance training for lean mass gain. Preserve protein intake (≈1.6–2.2 g/kg for many aiming to build/retain muscle) and monitor progress by tracking strength and body composition, not only the scale.
Ethnicity and individual variation
Ethnic differences in body composition and health risk at given weights are well documented (for example, some Asian populations have higher risk at lower weights). Use ideal-weight outputs as part of a broader assessment and consult clinicians for context-specific targets.
Summary
Ideal-weight formulas provide a quick, height-based target that can be useful for initial goal-setting, clinical dosing, and comparisons. Use multiple formulas to see a range, average them for a central estimate, and always interpret in light of body composition, function, age, and personal health goals.