Biological sex affects bone mass and muscle calculations.
Please enter a valid height.
Formulas are most accurate for heights over 5 feet (152 cm).
Please enter a valid age (18+).
Used for BMI interpretation ranges.
Small Frame (-10%)
Medium Frame (Average)
Large Frame (+10%)
Wrist circumference is often used to estimate frame size.
Estimated Ideal Weight
166 lbs
Range: 149 – 183 lbs
Based on the average of 4 clinical formulas adjusted for frame size.
Formula Breakdown
Formula
Calculated Weight
Description
Weight Formula Comparison
Comparison of Devine, Robinson, Miller, and Hamwi results
Understanding Your Ideal Weight Calculator Results
Maintaining a healthy weight is one of the most critical factors in preventing chronic diseases and ensuring long-term vitality. However, defining "ideal" is complex. This Ideal Weight Calculator utilizes four distinct, medically recognized formulas to provide a comprehensive estimation of what your body weight should ideally be, based on height, gender, and skeletal frame size.
Ideal Body Weight (IBW) is a calculation initially derived by pharmacologists to calculate proper drug dosages for patients. Over time, it became a standard metric in nutritional assessment and bariatric medicine. Unlike BMI, which is a broad ratio of mass to height, IBW formulas attempt to pinpoint a specific target weight that correlates with lowest mortality rates and optimal physiological function.
This calculator is designed for adults (18+) who want to understand their target weight zone. It is particularly useful for setting fitness goals, medical assessments, and nutritional planning. However, it is important to note that "ideal" is subjective to body composition; an athlete with high muscle mass may weigh more than their calculated IBW while remaining perfectly healthy.
The Formulas and Mathematical Explanation
To provide the most accurate range, this calculator employs the four most cited equations in medical literature. All formulas assume a base weight for a height of 5 feet, adding a specific amount for every inch over 5 feet.
Variable
Meaning
Unit
H
Height in inches over 5 feet
Inches
Base
Starting weight for 5ft height
Kilograms (kg)
Rate
Weight added per inch over 5ft
kg / inch
1. Devine Formula (1974)
Most commonly used formula for dosing medications.
Men: 50 kg + 2.3 kg × (Height in inches – 60)
Women: 45.5 kg + 2.3 kg × (Height in inches – 60)
2. Robinson Formula (1983)
Designed to improve upon Devine's formula using updated population data.
Men: 52 kg + 1.9 kg × (Height in inches – 60)
Women: 49 kg + 1.7 kg × (Height in inches – 60)
3. Miller Formula (1983)
Often results in a lower estimation, which some experts argue aligns better with modern longevity data.
Men: 56.2 kg + 1.41 kg × (Height in inches – 60)
Women: 53.1 kg + 1.36 kg × (Height in inches – 60)
4. Hamwi Formula (1964)
The "Rule of Thumb" often used in clinical dietetics settings.
Men: 48 kg + 2.7 kg × (Height in inches – 60)
Women: 45.5 kg + 2.2 kg × (Height in inches – 60)
Practical Examples (Real-World Use Cases)
Example 1: The Average Male
Profile: John is a 35-year-old male, 5'10" (70 inches) with a medium frame.
Input Height: 70 inches (10 inches over 5ft).
Devine Calculation: 50 + (2.3 × 10) = 73 kg (approx 161 lbs).
Financial/Health Interpretation: If John currently weighs 200 lbs, he is significantly above his ideal weight metric, potentially increasing insurance premiums and long-term health costs associated with metabolic syndrome.
Example 2: The Tall Female
Profile: Sarah is a 28-year-old female, 5'8″ (68 inches) with a large frame.
Input Height: 68 inches (8 inches over 5ft).
Hamwi Base Calculation: 45.5 + (2.2 × 8) = 63.1 kg (139 lbs).
Interpretation: Without the frame adjustment, Sarah might aim for an unrealistically low weight. The calculator helps set a sustainable target.
How to Use This Ideal Weight Calculator
Select Unit System: Choose between Imperial (lbs/ft) or Metric (kg/cm) based on your preference.
Enter Gender: This selects the specific coefficient for the formulas, accounting for biological differences in body mass.
Input Height: Be precise. Even an inch difference significantly alters the baseline calculation.
Select Frame Size: If your thumb and middle finger overlap easily around your wrist, select Small. If they touch, Medium. If they don't meet, Large.
Review Results: Look at the "Estimated Ideal Weight" for your average target, but consult the formula breakdown to see the range of medical opinion.
Key Factors That Affect Ideal Weight Results
While formulas provide a mathematical baseline, biological reality is nuanced. Consider these six factors:
Muscle Mass vs. Fat: Muscle is denser than fat. An athlete may weigh 20 lbs over their "ideal" weight yet have a low body fat percentage and excellent health.
Bone Density: Frame size inputs attempt to correct for this, but individuals with particularly dense bone structures will naturally weigh more.
Age: Metabolism slows with age, and some research suggests slightly higher weight in elderly populations may be protective against frailty.
Hydration Levels: Daily weight can fluctuate by 2-5 lbs based on water retention, salt intake, and glycogen stores.
Pregnancy and Nursing: These formulas do not apply to pregnant or breastfeeding women, who have distinct nutritional and weight requirements.
Health History: Previous medical conditions or chronic illnesses can alter what is considered a "healthy" weight for an individual, distinct from a statistical average.
Frequently Asked Questions (FAQ)
Why do the formulas give different results?
Each formula was developed using different population data sets and medical goals (e.g., drug dosing vs. longevity statistics). The variation gives you a healthy "range" rather than a single rigid number.
Is BMI or Ideal Weight more accurate?
Ideal Body Weight (IBW) is generally considered better for setting personal weight goals, while BMI is a screening tool for populations. Neither accounts perfectly for muscle mass.
Does age affect the calculation?
Strictly speaking, the traditional formulas do not include age as a variable. However, medical advice often adjusts the target range upward for older adults to ensure resilience.
What if I am an athlete?
If you are an athlete, these calculators will likely underestimate your healthy weight. Body fat percentage is a better metric for you than simple weight formulas.
How do I determine my frame size?
A common method is measuring wrist circumference. For a man over 5'5″, a wrist size 6.5″-7.5″ is medium. For a woman over 5'5″, 6.2″-6.5″ is medium.
Can I use this for children?
No. These formulas are strictly for adults over 18. Pediatric growth charts should be used for children.
What is the "healthy range"?
We calculate the range by taking the lowest result from the four formulas and the highest result, then applying a buffer (usually +/- 10%) to account for biological diversity.
Does this calculator calculate body fat?
No. This tool calculates weight based on height and frame. To measure body fat, you need calipers, DEXA scans, or bioimpedance scales.