Click to show tips
Try an Example
Pick a scenario to see how the calculator works, then adjust the values
Average Male
Calculate ideal weight for a 170 cm male using all formulas.
Key values: 170 cm · Male · Average of All
Petite Female
Calculate ideal weight for a 5'4" female with a small frame.
Key values: 5 ft 4 in · Female · Small frame
Athletic Build
Calculate ideal weight for a tall male with a large frame.
Key values: 185 cm · Male · Large frame
Documentation Contents
Introduction to Ideal Body Weight
Ideal Body Weight (IBW) is an estimated weight at which a person of a given height may experience optimal health outcomes. Various formulas have been developed over the decades to estimate IBW, each with its own methodology and applications.
What is IBW?
IBW formulas were originally developed for specific medical purposes, such as calculating medication dosages. They provide a reference point based on height and gender, though they don't account for factors like muscle mass, bone density, or body composition.
BMI and Healthy Weight
Body Mass Index (BMI) offers another approach to assessing healthy weight. A BMI between 18.5 and 24.9 is generally considered "healthy," though like IBW formulas, BMI has its limitations and shouldn't be the sole measure of health.
Disclaimer: This calculator provides estimates for educational purposes only. It is not a substitute for professional medical advice. Always consult a healthcare provider for personalized guidance.
How to Use This Calculator
Follow these steps to calculate your ideal body weight:
- Select your unit system - Choose between Metric (kg, cm) or Imperial (lb, ft, in).
- Enter your height - Accurate height measurement is crucial for accurate results. Measure without shoes, standing straight against a wall.
- Select your biological sex - IBW formulas use different base weights and increments for males and females.
- Choose your body frame size - This affects the Hamwi formula result. If unsure, select "Medium" or "Unknown."
- Select a calculation method - Choose a specific formula or view the average of all formulas.
Understanding the Inputs
| Input | Description |
|---|---|
| Unit System | Determines how you enter height and how results are displayed primarily |
| Height | Your height is the primary factor in all IBW calculations |
| Biological Sex | Formulas use different base weights for males and females |
| Frame Size | Only affects Hamwi formula; adjusts result by ±10% for small/large frames |
| Calculation Method | Choose a specific formula or see an average for a broader perspective |
Interpreting Your Results
The results display provides several pieces of information:
- Primary Result: Your ideal weight based on the selected formula or the average of all formulas.
- BMI Healthy Range: The weight range that corresponds to a BMI of 18.5-24.9 for your height.
- Formula Comparison: A table showing how each individual formula estimates your ideal weight.
Why Results Vary
Different formulas often produce different results because they were developed in different eras, for different populations, and with different medical goals in mind. A range of 5-10 kg (10-20 lbs) between formulas is common and normal.
Recommendation: Rather than fixating on a single number, consider the range provided by multiple formulas and the BMI healthy range as a target zone.
Methodology & Formulas
This calculator uses four established IBW formulas plus BMI-based calculations:
Robinson Formula (1983)
Developed by J.D. Robinson and colleagues, this formula is commonly used in clinical settings.
Miller Formula (1983)
The Miller formula tends to produce more moderate estimates.
Devine Formula (1974)
One of the most widely used formulas, originally developed for calculating drug dosages.
Hamwi Formula (1964)
Uniquely accounts for body frame size with ±10% adjustment.
Small frame: multiply by 0.9 | Large frame: multiply by 1.1
BMI-Based Healthy Weight Range
The healthy weight range is calculated using BMI thresholds of 18.5 and 24.9:
Where height is in meters
Applications
Personal Health Awareness
Use your ideal weight as a general reference point when setting health and fitness goals. Remember that health encompasses much more than weight alone—factors like cardiovascular fitness, strength, flexibility, and mental wellbeing are equally important.
Healthcare Discussions
These calculations can serve as a starting point for conversations with healthcare providers. Your doctor can help interpret results in the context of your individual health profile, medical history, and personal circumstances.
Note: IBW formulas are not intended for clinical diagnosis or treatment decisions. Medical professionals use multiple assessments and consider many factors beyond IBW when evaluating health.
Frequently Asked Questions
Which formula is the most accurate?
No single formula is definitively "most accurate" as each was developed for different purposes and populations. The average of multiple formulas often provides a reasonable middle ground. The Robinson and Miller formulas are considered more modern approaches.
Does this calculator apply to children, teenagers, or athletes?
These formulas were developed for typical adults. They may not be appropriate for children, adolescents (whose bodies are still developing), pregnant women, or athletes with higher muscle mass. Specialized assessments exist for these groups.
What if I don't know my frame size?
If you're unsure, select "Medium" or "Unknown." Frame size only affects the Hamwi formula, and the difference is typically ±10% of the calculated weight. The other formulas don't use frame size at all.
Why is my result different from other calculators?
Different calculators may use different formulas, rounding methods, or unit conversions. Some may also include additional factors. As long as the underlying formula is the same, results should be very similar.
Is the "ideal weight" the only healthy weight?
No. The IBW is a single estimate, but healthy weight exists on a spectrum. The BMI healthy range (18.5-24.9) provides a broader target. Individual factors like muscle mass, bone structure, and overall health markers matter more than hitting a specific number.
Limitations & Considerations
- Body Composition: These formulas don't account for muscle mass, body fat percentage, or bone density. An athlete may weigh more than their "ideal" weight due to muscle mass.
- Ethnicity: The original formulas were developed primarily using data from Western populations and may not be equally applicable to all ethnic groups.
- Age: While some formulas consider age, many don't. Body composition naturally changes with age, which these formulas don't fully capture.
- Individual Variation: Every body is unique. Two people of the same height, gender, and frame size may have very different optimal weights.
- Health Conditions: Certain medical conditions can affect what constitutes a healthy weight for an individual.
Not for medical use: This calculator is for informational purposes only. Do not use these results to make medical decisions or as a basis for treatment. Always consult qualified healthcare professionals.
Determining Frame Size
Body frame size can be estimated using wrist circumference relative to height. This is most commonly used with the Hamwi formula. Here's a general guide:
Wrist Measurement Method
Measure your wrist circumference just below the wrist bone (where you'd wear a watch).
| Height | Small Frame | Medium Frame | Large Frame |
|---|---|---|---|
| Women under 5'2" | < 5.5" | 5.5" - 5.75" | > 5.75" |
| Women 5'2" - 5'5" | < 6" | 6" - 6.25" | > 6.25" |
| Women over 5'5" | < 6.25" | 6.25" - 6.5" | > 6.5" |
| Men over 5'5" | < 6.5" | 6.5" - 7.5" | > 7.5" |
Note: These are general guidelines. If you're unsure, using "Medium" or "Unknown" will provide results based on an average frame size.
Specialized Calculators
Choose from 4 specialized versions of this calculator, each optimized for specific use cases and calculation methods.
Formula Type
4 CalculatorsRelated Calculators
6 CalculatorsMore Health calculators