How Much Should I Weigh?

The How Much Should I Weigh Calculator helps you find your ideal body weight using five scientifically validated formulas: Devine (1974), Robinson (1983), Miller (1983), Hamwi (1964), and the modern Peterson (2016). Instead of giving you a single number, this tool compares results across all formulas and shows your healthy weight range based on BMI guidelines, adjusted for body frame size.

What Is Ideal Body Weight (IBW)?

Ideal body weight is a weight considered optimal for your height and gender, associated with the lowest risk of health problems. Unlike a fixed number, it is better understood as a range. Medical professionals use IBW formulas for drug dosage calculations, nutritional planning, and health assessments. However, no single formula is perfect — each was developed using different datasets and methodologies, which is why this calculator shows results from all five major formulas.

The 5 Formulas We Use

"in over 60" means inches of height above 5 feet (60 inches). The Peterson formula uses target BMI of 22 and is height-universal.

How Body Frame Size Affects Ideal Weight

Body frame size adjusts your ideal weight by approximately ±10%. To estimate your frame size, wrap your thumb and longest finger around your wrist:

• Small frame: fingers overlap → subtract 10%
• Medium frame: fingers just touch → no adjustment
• Large frame: fingers don't meet → add 10%

Understanding BMI Ranges

The Body Mass Index (BMI) is calculated as weight (kg) divided by height squared (m²). The WHO classifies BMI ranges as:

• Underweight: BMI below 18.5
• Normal weight: BMI 18.5 – 24.9
• Overweight: BMI 25 – 29.9
• Obese: BMI 30 and above

Our calculator converts BMI 18.5 and 24.9 to actual weight for your specific height, giving you a concrete healthy weight range in pounds or kilograms.

How to Use This Calculator

1. Select your gender — formulas use different coefficients for male and female.
2. Enter your height — choose imperial (ft/in) or metric (cm) using the tabs.
3. Select body frame — small, medium, or large adjusts results by ±10%.
4. Enter current weight (optional) — to see a visual comparison and your BMI.
5. View results — compare all 5 formulas, see healthy BMI range, and explore formula details.

Limitations

These formulas provide estimates only. They do not account for:

• Muscle mass and body composition — athletes may have higher healthy weights
• Age — body composition changes with age
• Ethnicity — BMI thresholds may differ for certain populations
• Individual health conditions — pregnancy, medical conditions, etc.

Always consult a healthcare professional for personalized advice.

Frequently Asked Questions

How much should I weigh for my height?

Your ideal weight depends on height, gender, and body frame. For example, a 5'7" medium-frame female should weigh approximately 123–163 lbs (55.8–73.9 kg) based on BMI guidelines. Using the Devine formula specifically, the ideal weight would be about 140 lbs (63.6 kg). Our calculator uses 5 scientific formulas to give you a comprehensive range rather than a single number.

What are the different ideal weight formulas?

There are 5 major ideal body weight formulas: Devine (1974) — the most widely used in medicine; Robinson (1983) — based on Metropolitan Life Insurance data; Miller (1983) — tends to give higher estimates; Hamwi (1964) — popular among dietitians; and Peterson (2016) — the most modern BMI-based formula that works well across all heights.

Does body frame size affect ideal weight?

Yes, body frame size can adjust your ideal weight by approximately ±10%. People with a small frame typically have narrower bones and joints, so their ideal weight is about 10% less. Those with a large frame have wider bone structure and may weigh 10% more while still being at a healthy weight.

What is a healthy BMI range?

A healthy BMI range is 18.5 to 24.9 according to the World Health Organization and CDC. Below 18.5 is considered underweight, 25–29.9 is overweight, and 30 or above is classified as obese. However, BMI has limitations — it doesn't differentiate between muscle and fat, so athletes may have a high BMI while being perfectly healthy.

Why do different formulas give different ideal weights?

Different formulas give different results because they were developed at different times using different population data and methodologies. The Devine formula (1974) was designed for drug dosage calculation, the Hamwi formula (1964) for nutritional planning, and the Peterson formula (2016) uses modern BMI-based mathematics. Averaging across all formulas provides a more balanced and reliable estimate.

Additional Resources

• Human Body Weight - Wikipedia
• Body Mass Index - Wikipedia