Use this professional calculator to determine your ideal body weight based on clinically validated formulas.
Understanding how to calculate your optimal weight is the first step toward long-term health and fitness.
Male
Female
Biological sex affects body composition formulas.
Enter height in centimeters (e.g., 175).
Please enter a valid height between 100cm and 250cm.
Small Frame (-10%)
Medium Frame (Standard)
Large Frame (+10%)
Frame size adjusts the calculation for bone structure density.
Estimated Optimal Weight (Avg)
— kg
Average based on 4 major clinical formulas adjusted for frame size.
Healthy BMI Range
—
Devine Formula
—
Robinson Formula
—
Breakdown of results by different medical formulas.
Formula Method
Calculated Weight (kg)
Description
Chart Comparison: Shows the calculated optimal weight across different formulas versus the standard BMI range.
What is "Calculate Your Optimal Weight"?
When you set out to calculate your optimal weight, you are attempting to identify a body weight range that correlates with maximum longevity and minimal risk of chronic disease. Unlike a purely aesthetic goal, optimal weight calculations rely on anthropometric data—such as height, gender, and frame size—to estimate a healthy baseline.
Health professionals use these calculations to screen for nutritional status. However, a common misconception is that a single number defines health. In reality, when you calculate your optimal weight, you are finding a target range. Factors like muscle mass, bone density, and age play significant roles. This tool helps individuals, athletes, and patients establish a realistic weight goal based on established medical formulas rather than guesswork.
Optimal Weight Formulas and Mathematical Explanation
There is no single "perfect" equation to calculate your optimal weight. Instead, dietitians rely on several formulas developed over decades. Our calculator aggregates these to provide a comprehensive estimate. Below are the primary methods used.
1. The Devine Formula (1974)
Originally developed to calculate drug dosages, this is perhaps the most widely used formula medically.
Men: 50 kg + 2.3 kg per inch over 5 feet
Women: 45.5 kg + 2.3 kg per inch over 5 feet
2. The Robinson Formula (1983)
An adjustment of the Devine formula using slightly different base weights.
Men: 52 kg + 1.9 kg per inch over 5 feet
Women: 49 kg + 1.7 kg per inch over 5 feet
3. The Miller Formula (1983)
Often yields lower estimates, which some argue is more realistic for modern sedentary populations.
Men: 56.2 kg + 1.41 kg per inch over 5 feet
Women: 53.1 kg + 1.36 kg per inch over 5 feet
Variables Table
Key variables used in optimal weight calculations
Variable
Meaning
Unit
Typical Range
Base Weight
Starting constant for calculation
kg
45 – 56 kg
Height Increment
Weight added per unit of height
kg/inch
1.36 – 2.7 kg
Frame Multiplier
Adjustment for bone structure
Factor
0.9 (Small) – 1.1 (Large)
Practical Examples: Calculating Optimal Weight
Example 1: The Average Male
Profile: John is a 35-year-old male, 178 cm (approx. 5ft 10in) tall, with a medium frame. He wants to calculate his optimal weight to set a gym goal.
Result: Sarah's adjusted optimal weight is approximately 49kg, accounting for her smaller bone structure.
How to Use This Optimal Weight Calculator
Follow these steps to accurately calculate your optimal weight:
Select Gender: Choose Male or Female. This determines the base constant in the mathematical formulas.
Enter Height: Input your height in centimeters accurately. If you know your height in feet/inches, convert it (Feet × 30.48 + Inches × 2.54).
Select Frame Size:
Small: Wrist circumference is smaller than average for your height.
Medium: Average bone structure.
Large: Broad shoulders, larger wrists.
Review Results: The "Main Result" provides an average of the best formulas. Check the table to see how different experts (Devine, Miller, etc.) evaluate your height.
Analyze the Chart: Use the visual graph to see where your specific calculated weight falls compared to the broad "Healthy BMI" zone.
Key Factors That Affect Optimal Weight Results
When you calculate your optimal weight, the number on the screen is a theoretical ideal. Real-world biology is more complex. Consider these six factors:
Muscle Mass: Muscle tissue is denser than fat. An athlete may weigh significantly more than the calculator suggests but have a low body fat percentage and excellent health.
Bone Density: Genetic variances in skeletal density can account for 2-3 kg of weight difference between individuals of the same height.
Age: Metabolism slows with age. While the formulas don't explicitly change variables for age, older adults often require slightly different weight targets to maintain bone health and frailty resilience.
Body Fat Distribution: Visceral fat (around organs) is riskier than subcutaneous fat. Two people may have the same "optimal weight" but different health risks based on where fat is stored.
Hydration Status: Daily weight can fluctuate by 1-2 kg purely due to water retention, salt intake, or glycogen storage.
Pregnancy & Lactation: Standard formulas do not apply. Pregnant individuals must consult a doctor, as weight gain is necessary and healthy during this period.
Frequently Asked Questions (FAQ)
How often should I calculate my optimal weight?
You generally only need to calculate your optimal weight once as an adult, unless your height changes. However, you should weigh yourself regularly (weekly or monthly) to track progress relative to this goal.
Why does the Miller formula give a lower weight?
The Miller formula (1983) often results in lower estimates because it was derived based on insurance data that favored lighter individuals. It is often considered more restrictive than the Devine formula.
Is BMI accurate for bodybuilders?
No. BMI and standard weight formulas fail for bodybuilders because they cannot distinguish between muscle mass and fat mass. A bodybuilder might be classified as "overweight" despite having very low body fat.
Can I use this calculator for children?
No. These formulas (Devine, Robinson, etc.) are intended for adults over 18. Children require specialized growth charts (CDC or WHO percentiles) to assess healthy weight.
Does frame size really matter?
Yes. A person with a large skeletal frame naturally carries more non-fat mass. Adjusting for frame size prevents unrealistic dieting goals for broad-shouldered individuals.
What if my weight is outside the optimal range?
Being slightly outside the range is often normal. However, significant deviation may increase health risks. Consult a doctor or dietitian before starting a weight loss or weight gain program.
How do I measure my frame size?
A simple method is the wrist wrap test. Wrap your thumb and middle finger around your wrist. If they overlap, you have a small frame. If they touch, medium. If they don't meet, large.
Is the Devine formula the most accurate?
It is the most widely used in pharmacology for dosing medications based on ideal body weight. For general health, it serves as a very reliable baseline estimate.
Related Tools and Internal Resources
To get a complete picture of your health beyond just the ability to calculate your optimal weight, explore our other specialized tools:
Body Mass Index (BMI) CalculatorCheck if your weight falls within the WHO classification for underweight, normal, or overweight.