Use this professional calculator to determine your optimal weight range based on established medical formulas. Discover how height, gender, and age factors influence your ideal body metrics.
Metric (cm, kg)
Imperial (ft/in, lbs)
Select your preferred unit of measurement.
Male
Female
Biological sex affects bone density and muscle mass assumptions in formulas.
Used to contextualize results; medical IBW formulas are primarily height-based.
Please enter a valid age (15-100).
Enter your height in centimeters.
Please enter a valid height (100-250 cm).
Feet
Inches
Please enter a valid height.
Estimated Ideal Weight
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Based on the average of 4 medical formulas.
Robinson Formula
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Miller Formula
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Devine Formula
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Analysis Chart: Formula Comparison
Detailed Formula Breakdown
Formula Name
Calculated Weight
Primary Use Case
Devine (1974)
—
Standard for drug dosing
Robinson (1983)
—
Often used for men
Miller (1983)
—
Based on modern stats
Hamwi (1964)
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Original "Rule of Thumb"
*All weights are estimates. Consult a doctor for personal advice.
What is "Calculate Your Ideal Weight for Your Age"?
When people seek to calculate your ideal weight for your age, they are often looking for a benchmark to evaluate their health status. While the term implies that age is the primary driver, medical science primarily uses height and gender to determine Ideal Body Weight (IBW). However, age plays a critical context role. As we age, muscle mass tends to decrease and metabolism slows, meaning the "healthy" weight range might shift slightly in interpretation, even if the raw formula output remains constant.
This tool is designed for adults (18+) who want to set realistic health goals. It is not intended for children, pregnant women, or professional athletes with high muscle density. Unlike a simple BMI check, calculating your ideal weight using multiple formulas (like Devine, Robinson, and Miller) gives a more robust range of what constitutes a healthy mass for your specific frame.
A common misconception is that there is a single "perfect" number. In reality, a healthy weight is a range that allows for normal physiological function without placing excess stress on the cardiovascular or skeletal systems.
Ideal Weight Formulas and Mathematical Explanation
To accurately calculate your ideal weight, we employ four distinct, medically recognized algorithms. These formulas were originally developed for calculating drug dosages but have become the standard for weight assessment.
1. The Devine Formula (1974)
Most widely used standard. It assumes a base weight for a height of 5 feet and adds weight for every inch over 5 feet.
Male: 50.0 kg + 2.3 kg per inch over 5 feet
Female: 45.5 kg + 2.3 kg per inch over 5 feet
2. The Robinson Formula (1983)
Developed to refine the Devine formula using updated population data.
Male: 52 kg + 1.9 kg per inch over 5 feet
Female: 49 kg + 1.7 kg per inch over 5 feet
Variables Table
Variable
Meaning
Unit
Typical Range
Base Weight
Starting calculation value
kg
45 – 56 kg
Height Factor
Weight added per unit of height
kg/inch
1.4 – 2.7 kg
Height Threshold
Height at which addition starts
feet
Typically 5 ft (60 in)
Key variables used in standard Ideal Body Weight (IBW) equations.
Practical Examples (Real-World Use Cases)
Example 1: The Active Male
Scenario: John is a 35-year-old male, 5 feet 10 inches tall (178 cm). He wants to know his target weight for a marathon.
Input Height: 70 inches (10 inches over 5 ft).
Devine Calculation: 50 + (2.3 * 10) = 73.0 kg.
Robinson Calculation: 52 + (1.9 * 10) = 71.0 kg.
Result: John's ideal weight is likely between 71 kg and 73 kg (approx. 156-161 lbs).
Example 2: The Senior Female
Scenario: Susan is a 65-year-old female, 5 feet 4 inches tall (163 cm). She is concerned about joint health.
Input Height: 64 inches (4 inches over 5 ft).
Devine Calculation: 45.5 + (2.3 * 4) = 54.7 kg.
Miller Calculation: 53.1 + (1.36 * 4) = 58.54 kg.
Analysis: At age 65, being slightly heavier can be protective against bone density loss. While Devine suggests ~55 kg, the Miller formula (often higher for females) suggests ~58.5 kg. A target around 58 kg might be more realistic and sustainable.
How to Use This Ideal Weight Calculator
Select Your Unit System: Choose between Metric (cm/kg) or Imperial (ft/lbs) based on your preference.
Enter Biological Gender: Formulas differ significantly between males and females due to anatomical differences.
Input Current Age: This helps you contextually evaluate if you should be at the lower or higher end of the range (older adults may benefit from the higher end).
Input Precise Height: Height is the most sensitive variable. Ensure accuracy within 1 inch or 1 cm.
Review the Chart: Look at the bar chart to see how the four different formulas compare. If they are close, you have a high-confidence target. If they vary, aim for the average.
Key Factors That Affect Your Ideal Weight Results
When you calculate your ideal weight for your age, consider these six financial and physiological factors:
Muscle Mass vs. Fat: Muscle is denser than fat. A "high" weight might be healthy if it is lean mass. Financial cost: maintaining muscle often requires higher protein intake and gym fees.
Bone Density (Frame Size): People with larger wrist circumferences (large frames) should aim for the higher end of the calculated results (Hamwi formula often accounts for frame).
Age-Related Metabolism: As you age, your BMR (Basal Metabolic Rate) drops. Maintaining the strict "ideal" of your 20s might require significantly fewer calories, impacting your grocery budget and lifestyle.
Hormonal Changes: Especially for women post-menopause, fat distribution shifts. Fighting this natural shift to hit a specific number can be stressful and costly in terms of specialized supplements or medical advice.
Health Risks vs. Benefits: Being underweight (below Devine result) carries risks like osteoporosis, leading to high medical bills. Being slightly overweight in older age is sometimes correlated with better recovery from illness.
Hydration Levels: Daily weight fluctuates by 1-2 kg due to water. Don't let daily variance drive decision-making.
Frequently Asked Questions (FAQ)
Does age change my Ideal Body Weight calculation?
Technically, the standard formulas (Devine, Robinson) do not use age as a variable; they rely on height. However, medical interpretation changes with age. Doctors often recommend older adults maintain a slightly higher weight for frailty protection.
Which formula is the most accurate?
The Devine formula is the most widely accepted standard in medical settings for dosing. However, the Robinson formula is often considered more accurate for modern populations.
Why does the calculator give me different results?
Each formula was derived from different datasets and time periods (1964 vs 1983). The spread between them gives you a realistic "range" rather than a rigid single number.
Should I include my frame size?
The Hamwi formula allows for a ±10% adjustment for frame size. If you have a large frame, add 10% to the result shown.
Is BMI better than Ideal Weight formulas?
BMI is a general screening tool, while IBW formulas are specific targets. IBW is often preferred for setting clinical goals, while BMI is used for population health tracking.
Does this apply to athletes?
No. These formulas do not account for high muscle mass. Athletes should use body composition analysis (body fat %) instead.
How does height accuracy affect the result?
Significantly. Just one inch can change the ideal weight target by 2-3 kgs (approx 5-6 lbs).
Is it expensive to reach my ideal weight?
It can be. Changing your body composition requires investment in nutrition and exercise. However, the long-term financial savings on healthcare costs often outweigh the initial expense.