Ideal Weight Calculations: Which Formula Should You Use?

Understanding Ideal Weight

Ideal body weight isn't a magic number but rather a range associated with optimal health outcomes for a given height. These formulas were originally developed for medical purposes — particularly for calculating drug dosages — but have since become popular tools for setting weight goals.

It's crucial to understand that "ideal" weight depends on far more than height alone. Your body frame size — whether you're naturally small, medium, or large-boned — significantly affects what weight is healthy for you. Muscle mass matters too: a well-muscled person will weigh more than someone of the same height with less muscle, yet the more muscular person may be healthier.

Age, bone density, overall fitness level, and even cultural factors all play roles. The formulas we'll discuss provide useful starting points, but they're guidelines rather than prescriptions.

The Major Formulas Compared

Four formulas dominate discussions of ideal weight. Each was developed at different times and produces slightly different results.

The Devine formula, developed in 1974, is the most widely used in clinical settings. For men, it starts at 50 kg for someone 5 feet tall and adds 2.3 kg for each inch above that. For women, it starts at 45.5 kg with the same 2.3 kg per inch increment. This formula tends to give lower estimates, especially for taller individuals, which has led some critics to argue it sets unrealistic targets.

The Hamwi formula from 1964 takes a similar approach but with different numbers. Men start at 48 kg for 5 feet and add 2.7 kg per inch; women start at 45.5 kg and add 2.2 kg per inch. What sets Hamwi apart is its explicit adjustment for frame size: subtract 10 percent for small frames, add 10 percent for large frames.

The Robinson formula (1983) was designed as a modification of Devine with updated data. It gives men 52 kg at 5 feet plus 1.9 kg per inch, and women 49 kg plus 1.7 kg per inch. Results typically fall between the Devine and Hamwi estimates.

The Miller formula, also from 1983, aimed for a more realistic weight range. Men get 56.2 kg at 5 feet plus 1.41 kg per inch; women get 53.1 kg plus 1.36 kg per inch. Miller tends to produce higher estimates, particularly for shorter individuals.

Using Ideal Weight Data Constructively

Rather than fixating on a single number, use ideal weight calculations as one reference point among many. Start by looking at the range across formulas — if Devine suggests 65 kg and Miller suggests 72 kg, your realistic target zone is somewhere within that span.

Consider your starting point when setting goals. If you're significantly above the formula range, research shows that losing just 5 to 10 percent of your current weight delivers major health benefits — reduced blood pressure, improved blood sugar, lower cardiovascular risk — regardless of whether you reach an "ideal" weight.

Set incremental goals rather than focusing solely on a final destination. Aiming to lose 5 kilograms is mentally more manageable than thinking about 25 kilograms, and each milestone provides positive reinforcement to continue.

Combine ideal weight estimates with other metrics for a fuller picture. Your body fat percentage tells you about composition rather than just mass. Waist-hip ratio indicates how your fat is distributed and its associated health risks. How you feel — your energy, sleep quality, and ability to do activities you enjoy — matters more than any formula's output.

Limitations to Keep in Mind

All ideal weight formulas share important limitations. Most were developed using data from specific — often Western — populations and may not apply universally. Research shows that healthy BMI and weight ranges can differ across ethnic groups, yet the formulas make no such distinctions.

The formulas also ignore body composition entirely. A muscular person will "weigh too much" according to these calculations while being perfectly healthy or even exceptional. Conversely, someone with low muscle mass might fall within the "ideal" range while carrying an unhealthy proportion of body fat.

Age isn't considered either. Body composition naturally shifts over time — older adults typically have more fat and less muscle than younger people at the same weight. Some research suggests that slightly higher weights in older age may actually be protective, yet the formulas use the same calculation regardless of whether you're 25 or 75.

Perhaps most importantly, health encompasses far more than weight. Blood pressure, cholesterol, blood sugar, fitness level, sleep quality, mental health — these factors matter enormously and can't be captured by any formula based on height alone.

Conclusion

Ideal weight formulas provide useful reference points, but they're just one tool among many for understanding your health. The best weight for you is one where you feel energetic, can do the activities you enjoy, and maintain good health markers — regardless of what any formula says.

Use these calculations as a starting point for goal-setting, not as an absolute destination. Combine them with your BMI, body fat percentage, and waist-hip ratio for a complete picture. Listen to your body, and focus on sustainable habits rather than chasing a number. The healthiest approach treats weight as one indicator of wellbeing among many, not the sole measure of success.

Curious about your ideal weight range? Use our free calculator to see estimates from all major formulas and find a healthy target range for your height.