About This Tool
Find your ideal body weight by comparing results from four widely used clinical formulas: Devine, Robinson, Miller, and Hamwi. Each formula takes a slightly different approach to estimating a healthy weight based on your height and gender, and no single formula is universally accepted as the best. By showing all four results side by side along with the BMI-based healthy weight range, this calculator gives you a complete picture rather than a single number. Enter your gender and height, choose imperial or metric units, and see instant results with a visual bar chart comparison. Free, instant, and no signup needed. For informational purposes only. Not medical advice. Consult a healthcare provider before making any decisions about weight management. These formulas were developed decades ago and do not account for body composition, muscle mass, bone density, ethnicity, or age.
The Four Ideal Weight Formulas Explained
Each formula estimates ideal body weight (IBW) in kilograms based on height in inches above 5 feet (60 inches). All four were originally developed for pharmaceutical dosing calculations and later adopted for general health guidance.
- Devine (1974): Men: 50 + 2.3 kg per inch over 5 ft. Women: 45.5 + 2.3 kg per inch over 5 ft. This is the most commonly referenced formula in clinical settings and is the basis for many drug dosing calculations.
- Robinson (1983): Men: 52 + 1.9 kg per inch over 5 ft. Women: 49 + 1.7 kg per inch over 5 ft. Robinson modified the Devine formula to produce estimates that better matched population data available in the 1980s.
- Miller (1983): Men: 56.2 + 1.41 kg per inch over 5 ft. Women: 53.1 + 1.36 kg per inch over 5 ft. The Miller formula produces higher baseline weights and smaller increases per inch, resulting in a narrower spread between short and tall individuals.
- Hamwi (1964): Men: 48 + 2.7 kg per inch over 5 ft. Women: 45.5 + 2.2 kg per inch over 5 ft. The oldest of the four formulas, commonly used in nutrition and dietetics.
Why Multiple Formulas Matter
No single ideal weight formula is definitively correct because "ideal weight" is not a precise medical concept. Each formula was derived from different datasets and populations, and they can produce results that vary by 10-15 pounds or more, especially for taller individuals.
Looking at the range across all four formulas gives a more realistic target zone than relying on any single number. If all four formulas agree within a narrow range for your height, you can have higher confidence in that estimate. If they diverge significantly, it highlights the inherent uncertainty in these calculations and the need to consider other factors like body composition and fitness level.
The BMI-based healthy range (18.5-24.9) provides an additional reference point. This range is broader than what the formulas typically produce and accounts for natural variation in body types. Many healthcare providers use BMI as a screening tool alongside other assessments rather than as a definitive health indicator.
Limitations of Ideal Weight Formulas
All four formulas share several important limitations that you should understand before using the results:
- No body composition consideration: A muscular athlete and a sedentary person of the same height will get identical results, even though their healthy weights may differ significantly.
- Age not factored: Body composition changes with age. Older adults naturally have less muscle and more fat at the same weight compared to younger adults.
- Ethnicity differences: These formulas were developed primarily from data on Western populations and may not accurately reflect healthy weights for all ethnic groups.
- Frame size ignored: People with larger bone structures naturally weigh more at the same height without being overweight.
- Medical conditions: Certain conditions, medications, and physical disabilities affect what constitutes a healthy weight for an individual.
Use these results as general reference points, not absolute targets. Your healthcare provider can help determine a healthy weight range based on your complete health picture.
BMI vs. Ideal Weight Formulas
BMI (Body Mass Index) and ideal weight formulas approach the question from different directions. BMI calculates a ratio of weight to height squared and classifies the result into categories (underweight, normal, overweight, obese). Ideal weight formulas directly estimate a target weight in pounds or kilograms.
The BMI healthy range (18.5-24.9) produces a wider weight range than most individual formulas because it encompasses the full spectrum of normal body types. For a person who is 5'10" (70 inches), the BMI healthy range spans approximately 129-174 lbs, while the four ideal weight formulas cluster more tightly around 149-166 lbs.
Neither approach is superior. BMI is simpler to calculate and has extensive epidemiological data supporting its use as a screening tool. Ideal weight formulas provide a more specific target but with less statistical backing. Both share the fundamental limitation of not measuring body composition directly.
How to Use These Results
Treat the range across all four formulas as a general guideline, not a prescription. Here are practical ways to use the information:
- Set realistic goals: If you are working toward a healthier weight, the formula range gives you a reasonable target zone. Aim for gradual progress rather than hitting an exact number.
- Discuss with your doctor: Bring these results to your next appointment as a conversation starter. Your provider can evaluate the numbers in context with your health history, lab work, and fitness level.
- Track trends: The specific number matters less than the direction of change over time. Gradual movement toward the recommended range is more sustainable than rapid changes.
- Consider body composition: If you exercise regularly and carry significant muscle mass, your healthy weight may be above what these formulas suggest. A body fat measurement provides a more complete picture than weight alone.
Frequently Asked Questions
Which ideal weight formula is the most accurate?
No single formula is definitively the most accurate because "ideal weight" varies by individual. The Devine formula is the most widely used in clinical settings, primarily for medication dosing. For general health guidance, looking at the range across all four formulas and the BMI healthy range provides a more realistic picture than relying on any single formula.
Why does my ideal weight differ from what I expected?
These formulas estimate weight based only on height and gender. They do not account for muscle mass, bone structure, age, or body fat percentage. A person who exercises regularly and carries significant lean muscle may have a healthy weight above what these formulas suggest. The results are general guidelines, not personalized recommendations.
Can I use this calculator if I am under 5 feet tall?
The formulas were designed for adults at least 5 feet (60 inches or 152 cm) tall. For heights below 5 feet, the calculator returns the baseline value for each formula. Results for very short or very tall individuals are less reliable. Consult a healthcare provider for personalized guidance if you fall outside the typical height range.
Is ideal weight different for older adults?
Yes. Research suggests that slightly higher BMI values (25-27) may actually be associated with lower mortality risk in adults over 65. The standard formulas do not adjust for age. Older adults should discuss appropriate weight targets with their healthcare provider, taking into account bone density, muscle mass, and overall health status.
How often should I check my ideal weight?
Your ideal weight based on these formulas will only change if your height changes (which is rare in adulthood) or if you switch between the male and female calculations. The results are static reference points. What matters more is tracking your actual weight trends over time and discussing any concerns with a healthcare provider during regular checkups.
Should I aim for the lowest number in the range?
Not necessarily. The lowest number is not inherently healthier than a higher number within the range. Being underweight carries its own health risks, including weakened immune function, bone loss, and nutrient deficiencies. A weight within the overall range that allows you to feel energetic, exercise comfortably, and maintain good lab values is generally more important than hitting the lowest possible number.