Your Comprehensive Guide and Interactive Calculator
Calculate Your Target Weight
Use this calculator to estimate your healthy target weight range based on your current height and chosen weight classification method.
Enter your height in centimeters (cm).
Body Mass Index (BMI)
Robinson Formula (Men)
Robinson Formula (Women)
Devine Formula (Men)
Devine Formula (Women)
Hamwi Formula (Men)
Hamwi Formula (Women)
Select the method for calculating ideal body weight.
Your Target Weight Range
—
Lower Bound: —
Upper Bound: —
Method Used: —
Formula Used: Calculations are based on standard physiological formulas. For BMI, the target weight is derived from the healthy BMI range (18.5-24.9). For the other methods (Robinson, Devine, Hamwi), they provide a baseline ideal weight from which a small range is often considered.
Target Weight Range Chart
Chart will appear after calculation.
Weight Classification Table (Metric)
Classification
BMI Range
Ideal Weight Formula (Example for 175cm)
Underweight
< 18.5
< 57.3 kg
Healthy Weight
18.5 – 24.9
57.3 – 77.1 kg
Overweight
25 – 29.9
77.1 – 92.9 kg
Obese
≥ 30
≥ 92.9 kg
Robinson (Men)
N/A
50 kg + 2.2 kg/inch (Height: 175cm = ~69 inches) ≈ 201.8 lbs ≈ 91.5 kg
Devine (Men)
N/A
50 kg + 2.3 kg/inch (Height: 175cm = ~69 inches) ≈ 208.7 lbs ≈ 94.7 kg
Hamwi (Men)
N/A
48 kg + 2.7 kg/inch (Height: 175cm = ~69 inches) ≈ 234.3 lbs ≈ 106.3 kg
What is Target Weight?
Target weight, often referred to as ideal body weight (IBW) or healthy weight, is an estimated weight that is considered optimal for a person's height, sex, and frame to promote good health and reduce the risk of weight-related diseases. It's not a rigid number but rather a range that signifies a body composition associated with lower risks of conditions like heart disease, diabetes, and certain cancers. Understanding how to calculate target weight is a crucial step for individuals looking to manage their weight effectively, whether aiming for weight loss or gain.
Who Should Use It?
Anyone seeking to understand a healthy weight range for themselves should consider calculating their target weight. This includes individuals who:
Are planning to start a weight loss or gain program.
Want to assess if their current weight falls within a healthy range.
Are looking for personalized health and fitness goals.
Are interested in understanding the basic metrics used in health assessments.
Common Misconceptions
Several myths surround target weight. One common misconception is that it's a single, exact number. In reality, it's a range, and individual variations exist. Another is that IBW formulas are universally applicable; they are estimations and don't account for body composition (muscle vs. fat), bone density, or specific medical conditions. Lastly, focusing solely on weight can be misleading; overall health involves diet, exercise, sleep, and stress management, not just a number on the scale.
Target Weight Formula and Mathematical Explanation
Calculating target weight involves various formulas, each with its own approach. The most common methods are based on Body Mass Index (BMI) or specific predictive formulas like the Robinson, Devine, and Hamwi equations.
Body Mass Index (BMI)
BMI is a widely used screening tool that relates weight to height. It's calculated by dividing weight (in kilograms) by height squared (in meters). The formula is:
BMI = weight (kg) / [height (m)]²
To calculate target weight using BMI, we use the healthy BMI range (18.5 to 24.9). Rearranging the formula to solve for weight:
Target Weight (kg) = Desired BMI × [height (m)]²
For example, if someone is 1.75 meters tall, their target weight range would be:
Lower end (BMI 18.5): 18.5 × (1.75)² ≈ 57.2 kg
Upper end (BMI 24.9): 24.9 × (1.75)² ≈ 76.4 kg
Predictive Formulas (Robinson, Devine, Hamwi)
These formulas estimate ideal body weight based on height and sex. They were developed historically and offer a single baseline weight, often with a small range considered acceptable around it.
Robinson Formula:
Men: 52 kg + 1.9 kg per inch over 5 feet
Women: 49 kg + 1.7 kg per inch over 5 feet
Devine Formula:
Men: 50 kg + 2.3 kg per inch over 5 feet
Women: 45.5 kg + 2.3 kg per inch over 5 feet
Hamwi Formula:
Men: 48 kg + 2.7 kg per inch over 5 feet
Women: 45.5 kg + 2.2 kg per inch over 5 feet
To use these, you first convert height to feet and inches. For example, 175 cm is approximately 5 feet 9 inches (69 inches). The inches over 5 feet is 9 inches.
Variable Explanations
Variable
Meaning
Unit
Typical Range
Height
The vertical distance from the base to the top of a person's body.
Centimeters (cm), Meters (m), Inches
Variable
Weight
A measure of the force of gravity on a body's mass.
Kilograms (kg), Pounds (lbs)
Variable
BMI
Body Mass Index, a ratio of weight to height squared.
kg/m²
18.5 – 24.9 (Healthy)
Ideal Body Weight (IBW)
A calculated weight considered optimal for health.
Kilograms (kg), Pounds (lbs)
Variable (depends on height, sex, formula)
It's important to remember that these formulas provide estimates. Consult with a healthcare professional for personalized advice on your target weight.
Practical Examples (Real-World Use Cases)
Example 1: Using BMI for a 30-Year-Old Woman
Scenario: Sarah is a 30-year-old woman who is 165 cm tall. She wants to know her healthy weight range based on the standard BMI classification.
Height in meters: 1.65 m
Height squared: (1.65 m)² = 2.7225 m²
Healthy BMI Range: 18.5 to 24.9
Target Weight (Lower Bound): 18.5 × 2.7225 ≈ 50.4 kg
Target Weight (Upper Bound): 24.9 × 2.7225 ≈ 67.8 kg
Result Interpretation: Sarah's target weight range, based on a healthy BMI, is approximately 50.4 kg to 67.8 kg. If her current weight falls outside this range, she might consider consulting a doctor or nutritionist to discuss sustainable lifestyle changes.
Example 2: Using Robinson Formula for a 45-Year-Old Man
Scenario: Mark is a 45-year-old man who is 180 cm tall. He's interested in using the Robinson formula to estimate his ideal body weight.
Height in feet and inches: 180 cm is approximately 5 feet 11 inches (71 inches).
Inches over 5 feet: 11 inches.
Robinson Formula for Men: 52 kg + 1.9 kg/inch
Calculation: 52 kg + (1.9 kg/inch × 11 inches) = 52 kg + 20.9 kg = 72.9 kg
Result Interpretation: According to the Robinson formula, Mark's estimated ideal body weight is approximately 72.9 kg. While this formula provides a single number, healthcare professionals often consider a range (e.g., +/- 10%) around this figure to account for individual variations and body composition.
How to Use This Target Weight Calculator
Our interactive calculator simplifies the process of determining your target weight. Follow these easy steps:
Enter Your Height: Input your height accurately in centimeters (cm) into the "Height" field.
Select Classification Method: Choose the weight classification method you wish to use from the dropdown menu. The options include:
Body Mass Index (BMI): Provides a healthy weight range based on the 18.5-24.9 BMI classification.
Robinson, Devine, Hamwi Formulas: These provide specific formulas for men and women, offering a baseline ideal weight.
Calculate: Click the "Calculate Target Weight" button.
How to Read Results
Once you click "Calculate," the calculator will display:
Primary Result (Large Font): This shows your estimated target weight or the mid-point of your target range.
Lower Bound & Upper Bound: These values define the healthy or ideal weight range based on your selected method. For BMI, this is the range corresponding to a healthy BMI score. For the other formulas, it might represent a commonly accepted variation around the calculated ideal weight.
Method Used: Confirms which formula or method was applied for the calculation.
Chart & Table: Visual representations and tabular data provide context and comparative information.
Decision-Making Guidance
Use these results as a guide, not a strict prescription. If your current weight is significantly outside the calculated range, it's a signal to consider your health habits. Consult with a healthcare provider or a registered dietitian to develop a personalized plan that considers your unique health status, body composition, lifestyle, and goals. Remember that sustainable health improvements involve more than just reaching a specific number on the scale.
Key Factors That Affect Target Weight Results
While formulas provide a starting point for how to calculate target weight, several crucial factors influence what a truly healthy weight means for an individual:
Body Composition (Muscle vs. Fat Mass)
Formulas often don't distinguish between muscle and fat. A very muscular person might have a higher weight but be very healthy due to low body fat percentage. Conversely, someone lighter might have a higher body fat percentage, posing health risks. Target weight should ideally consider body fat percentage.
Bone Density and Frame Size
Individuals with larger bone structures or denser bones may naturally weigh more than those with smaller frames, even if they are at a similar body fat percentage. Some formulas attempt to account for frame size, but it remains an estimation.
Age
Metabolism and body composition can change with age. What's considered ideal weight might shift slightly throughout different life stages. For instance, muscle mass tends to decrease and fat mass increase with age if lifestyle doesn't adapt.
Sex
Biological differences in body composition, hormonal profiles, and typical fat distribution mean that ideal weight calculations often differ between men and women.
Genetics
Your genetic makeup plays a role in your metabolism, body shape, and predisposition to store fat. These inherent factors mean that a "one-size-fits-all" target weight might not be perfectly suitable for everyone.
Activity Level
A highly active individual, especially one engaged in strength training, will likely have more muscle mass than a sedentary person of the same height and weight. This impacts the interpretation of weight and BMI. Fitness goals should complement, not just be dictated by, target weight numbers.
Medical Conditions and Medications
Certain health conditions (e.g., thyroid issues, edema) and medications can affect body weight independently of diet and exercise. These need to be considered by a healthcare professional when determining an appropriate weight goal.
Always consult a healthcare professional to interpret these results in the context of your overall health and well-being.
Frequently Asked Questions (FAQ)
Q1: Are these target weight formulas accurate?
A1: These formulas provide estimations for ideal or healthy body weight. They are useful tools for general assessment but do not account for individual body composition (muscle vs. fat), bone density, or specific health conditions. For precise health guidance, consult a healthcare professional.
Q2: Can I use the BMI calculator if I'm very muscular?
A2: BMI can be misleading for highly muscular individuals, as muscle is denser than fat. A muscular person might fall into the "overweight" BMI category despite having a low body fat percentage and being very healthy. Consider body fat percentage as a more accurate measure in such cases.
Q3: What's the difference between target weight and ideal body weight?
A3: The terms are often used interchangeably. "Target weight" is generally a goal-oriented term, while "ideal body weight" (IBW) refers to a calculated estimate considered optimal for health. Both represent a weight range associated with reduced health risks.
Q4: How often should I recalculate my target weight?
A4: You generally don't need to recalculate your target weight frequently unless there are significant changes in your health, lifestyle, or if you're undertaking a specific weight management program. The formulas are based on your fixed height, which doesn't change.
Q5: Should I aim for the lower or upper end of the target weight range?
A5: This depends on individual factors like body composition, fitness goals, and personal health. Often, aiming for the middle of the healthy range is a good starting point. Discussing this with a doctor or nutritionist can provide personalized advice.
Q6: What if my current weight is far from the target weight?
A6: If your current weight is significantly outside the healthy range, it's a good indicator to review your lifestyle habits. Consult with a healthcare professional to create a safe and effective plan for gradual, sustainable weight management.
Q7: Do these formulas account for pregnancy?
A7: No, these formulas are not designed for pregnant individuals. Weight gain during pregnancy is specific and requires medical supervision. Consult your obstetrician for guidance on appropriate weight management during pregnancy.
Q8: What are the limitations of predictive formulas like Robinson, Devine, and Hamwi?
A8: These formulas were developed decades ago and may not accurately reflect modern body compositions or diverse populations. They are best used as a rough guide and should be interpreted alongside other health indicators.