Ideal Weight Calculator
Find your ideal weight range using four scientifically-backed formulas. Enter your height and gender to see results from Devine, Robinson, Miller, and Hamwi methods.
What Is Ideal Body Weight?
Ideal body weight (IBW) is a target weight range based on your height and gender that is associated with the lowest risk of weight-related health problems. Unlike BMI, which gives a single number, ideal weight formulas provide specific weight targets that can serve as practical goals for weight management.
The concept of ideal body weight emerged in the mid-20th century as researchers and clinicians sought simple ways to estimate healthy weights for their patients. Insurance companies, particularly Metropolitan Life, published some of the earliest ideal weight tables based on mortality data. Later, medical researchers developed mathematical formulas that could estimate ideal weight from height alone.
Today, four formulas are widely used in clinical practice: Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). Each formula takes a slightly different approach, yielding a range of ideal weights rather than a single number. This range is actually more useful than a single target because it acknowledges the natural variation in body types and compositions.
The Four Ideal Weight Formulas Explained
All four formulas share a similar structure: they start with a base weight for a height of 5 feet (152.4 cm) and add a specific amount for each additional inch of height. The differences lie in the base weights and per-inch increments.
The Devine formula is the most widely used, particularly in pharmaceutical settings where it was originally developed for calculating drug dosages. For men, it starts at 50 kg for 5 feet and adds 2.3 kg per inch. For women, it starts at 45.5 kg and adds 2.3 kg per inch. Despite being designed for drug dosing rather than health assessment, it has become the standard reference in many clinical settings.
The Robinson formula was developed as a refinement of the Devine formula using updated population data. It tends to give slightly lower ideal weights for men (starting at 52 kg but adding only 1.9 kg per inch) and for women (starting at 49 kg with 1.7 kg per inch). Many clinicians consider it a more accurate reflection of healthy weight.
The Miller formula generally produces the highest ideal weight estimates, starting at 56.2 kg for men and 53.1 kg for women but with smaller per-inch increments (1.41 kg for men, 1.36 kg for women). This makes it particularly different for taller individuals, where the gap between Miller and other formulas widens.
The Hamwi formula is one of the oldest, created by Dr. Hamwi in 1964. It starts at 48 kg for men and 45.5 kg for women, with increments of 2.7 kg and 2.2 kg per inch respectively. It is widely used in dietetic practice and tends to fall in the middle of the range for most heights.
Limitations of Ideal Weight Formulas
While ideal weight formulas are useful as general guidelines, they have important limitations that should be considered. They do not account for body composition, meaning a muscular athlete may have an ideal weight that is significantly higher than what these formulas suggest. Similarly, a person with a large bone structure may naturally weigh more than the formula recommendations.
These formulas were also developed primarily using data from specific populations and may not be equally applicable across all ethnic groups, age ranges, or body types. They do not consider factors like muscle mass, bone density, age-related changes in body composition, or individual health conditions.
For a more complete assessment of whether you are at a healthy weight, consider using multiple tools together: ideal weight formulas for a target range, BMI for a standardized health classification, body fat percentage for actual body composition, and waist circumference for abdominal fat risk. Working with a healthcare provider or certified personal trainer can help you interpret these numbers in the context of your individual health profile.
How to Reach Your Ideal Weight
Reaching your ideal weight is a gradual process that requires sustainable changes to your diet and exercise habits. If you need to lose weight, aim for a moderate calorie deficit of 300-500 calories per day, which translates to about 0.5-1 pound of weight loss per week. Rapid weight loss through extreme dieting is counterproductive because it leads to muscle loss, metabolic adaptation, and rebound weight gain.
If you need to gain weight to reach your ideal range, focus on a calorie surplus of 200-300 calories per day combined with strength training. This ensures that weight gain comes primarily from muscle rather than fat. Prioritize protein intake (0.7-1 gram per pound of body weight) and compound exercises like squats, deadlifts, and presses.
Regardless of your direction, consistency is key. Small, sustainable changes to your eating habits and exercise routine will yield better long-term results than dramatic short-term interventions. Working with a personal trainer or registered dietitian can provide the accountability and expertise needed to reach your ideal weight safely and effectively.
Frequently Asked Questions
What is the most accurate ideal weight formula?
No single formula is universally most accurate. The best approach is to look at the range provided by all four formulas and use the average as a general target. Individual factors like muscle mass, bone structure, and body composition should also be considered.
How is ideal weight calculated?
Ideal weight formulas use height as the primary input. They start with a base weight for 5 feet and add weight for each inch above that. The specific base weight and per-inch addition vary by formula and gender.
Should I aim for my ideal weight?
Ideal weight provides a useful reference point but should not be your only goal. Consider body fat percentage, fitness level, and overall health markers. A muscular person may weigh more than their calculated ideal weight while being perfectly healthy.
Why do different formulas give different ideal weights?
The formulas were developed at different times using different data sets and assumptions. Devine (1974) was designed for drug dosing, Hamwi (1964) was among the earliest, and Robinson (1983) and Miller (1983) were later refinements. The range they provide is actually more useful than any single number.