Use our professional calculator to determine your ideal body weight based on medical standards.
Perfect Weight Calculator
Male
Female
Formulas differ significantly based on biological sex.
Enter height in feet and inches (e.g., 5′ 10″).
Please enter a valid height.
Medium (Average)
Small (Light build)
Large (Heavy build)
Adjusts the result by ±10% to account for bone structure.
Estimated Perfect Weight
166 lbs
Healthy Range: 136 – 184 lbs
Method Used: Average of 4 Major Medical Formulas
Formula
Calculation Result
Medical Context
Comparison of different medical ideal weight formulas vs Healthy BMI Range
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What is "How to Calculate My Perfect Weight"?
When people ask how to calculate my perfect weight, they are typically looking for a medically standardized metric known as Ideal Body Weight (IBW). Unlike a simple scale reading, the concept of a "perfect" weight is rooted in actuarial data and medical formulas designed to estimate a weight associated with maximum longevity and minimum risk of chronic disease.
The process of determining how to calculate my perfect weight is not about aesthetic perfection but about physiological balance. Doctors and dietitians use these calculations to dose medications, assess nutritional needs, and set realistic health goals. However, it is a common misconception that there is one single "perfect" number. Instead, there is a healthy range based on height, gender, and bone structure.
Note: If you are an athlete with high muscle mass, standard IBW formulas may underestimate your healthy weight. Always consider body composition alongside these calculations.
Perfect Weight Formula and Mathematical Explanation
To understand how to calculate my perfect weight accurately, we must look at the four primary equations used in the medical community. These formulas were derived over decades to standardize patient care.
1. The Devine Formula (1974)
Most widely used for dosing medications.
Men: 50.0 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)
Often used as a modification of Devine's formula.
Men: 52 kg + 1.9 kg per inch over 5 feet
Women: 49 kg + 1.7 kg per inch over 5 feet
Variables Table
Variable
Meaning
Unit
Typical Range
Base Weight
Starting weight for 5ft height
kg / lbs
45-56 kg
Height Factor
Weight added per inch over 5ft
kg / inch
1.4 – 2.7 kg
Frame Size
Bone structure adjustment
%
±10%
Practical Examples (Real-World Use Cases)
Here are two detailed examples of how to calculate my perfect weight using the calculator above.
Example 1: The Average Male
Profile: John is a 5'10" male with a medium frame.
Frame Adjustment: Small frame requires subtracting 10%.
Final Calculation: 120 lbs – 12 lbs = 108 lbs.
Interpretation: Sarah's target weight is significantly lower than average due to her frame size.
How to Use This Perfect Weight Calculator
Using this tool to solve how to calculate my perfect weight is straightforward:
Select Gender: Choose Male or Female. This adjusts the base weight constant in the formula.
Enter Height: Input your height in feet and inches. If you are exactly 5 feet, enter 0 in the inches field.
Select Frame Size: If you have a smaller wrist circumference relative to your height, choose "Small". For broader shoulders and wrists, choose "Large".
Review Results: The calculator provides an average "Perfect Weight" and a "Healthy BMI Range".
Key Factors That Affect Perfect Weight Results
When asking how to calculate my perfect weight, consider these six critical factors that formulas often overlook:
Muscle Mass: Muscle is denser than fat. A bodybuilder may be labeled "overweight" by these formulas despite having low body fat.
Bone Density: Genetic variances in skeletal weight can account for a 5-10lb difference in actual ideal weight.
Age: Metabolic rate slows with age. While the formulas don't change, the strictly "ideal" weight might be harder to maintain for seniors, where a slightly higher BMI is often protective.
Hydration Levels: Daily weight fluctuations of 1-3 lbs are normal and due to water retention, not fat gain.
Fat Distribution: Visceral fat (belly fat) is higher risk than subcutaneous fat. Two people of the same "perfect weight" may have different health risks.
Pregnancy history: Women may have a different physiological baseline after childbirth.
Frequently Asked Questions (FAQ)
1. Is the result from "how to calculate my perfect weight" strict?
No. Consider it a target center-point. A healthy weight is generally considered to be within ±10% of the calculated IBW or within the BMI range of 18.5 to 24.9.
2. Why do different formulas give different results?
They were developed based on different population data sets and decades. The Miller formula (1983), for instance, often yields lower weights than the Devine formula.
3. What if I am under 5 feet tall?
Most IBW formulas start at 5 feet. For heights under 5 feet, a common rule of thumb is to subtract 2-5 lbs for every inch under 5 feet, though BMI is a better metric for short stature.
4. Does frame size really matter?
Yes. A large-framed individual carrying the weight of a small-framed individual would likely be unhealthy. The Hamwi formula explicitly accounts for this.
5. Which formula is the most accurate?
The Devine formula is the most commonly used in clinical settings for dosing medications, while the Hamwi method is popular among dietitians for estimating caloric needs.
6. How often should I calculate my perfect weight?
Your target "perfect weight" does not change unless you grow taller. However, you should monitor your actual weight weekly.
7. Can I use this for children?
No. These formulas are strictly for adults (age 18+). Children require specialized growth charts from pediatricians.
8. Is BMI better than IBW?
They serve different purposes. BMI screens for weight categories (underweight, obese), while IBW gives a specific target number often used for medical dosing.
Related Tools and Internal Resources
Explore more tools to help you manage your health journey:
// CORE LOGIC – NO CONST/LET, VAR ONLY
// Initial calculation on load
window.onload = function() {
calculatePerfectWeight();
};
function calculatePerfectWeight() {
// 1. Get Inputs
var gender = document.getElementById('gender').value;
var ft = parseFloat(document.getElementById('heightFt').value);
var inch = parseFloat(document.getElementById('heightIn').value);
var frame = document.getElementById('frameSize').value;
// 2. Validation
var errorDiv = document.getElementById('heightError');
if (isNaN(ft) || isNaN(inch) || ft < 1 || inch < 0) {
errorDiv.style.display = 'block';
return; // Stop calculation
} else {
errorDiv.style.display = 'none';
}
// 3. Convert Height
var totalInches = (ft * 12) + inch;
var inchesOver5ft = totalInches – 60;
var heightInMeters = totalInches * 0.0254;
// Base Logic: If under 5ft, these formulas don't technically apply well.
// We will clamp inchesOver5ft to 0 for the base calculation or handle negatives
// by subtracting the rate. Standard practice for short stature in these formulas
// is actually subtracting the 'per inch' value, so we allow negative inchesOver5ft.
// 4. Calculate Formulas (Results in KG)
var devine = 0;
var robinson = 0;
var miller = 0;
var hamwi = 0;
if (gender === 'male') {
// Male Formulas
devine = 50.0 + (2.3 * inchesOver5ft);
robinson = 52.0 + (1.9 * inchesOver5ft);
miller = 56.2 + (1.41 * inchesOver5ft);
hamwi = 48.0 + (2.7 * inchesOver5ft);
} else {
// Female Formulas
devine = 45.5 + (2.3 * inchesOver5ft);
robinson = 49.0 + (1.7 * inchesOver5ft);
miller = 53.1 + (1.36 * inchesOver5ft);
hamwi = 45.5 + (2.2 * inchesOver5ft);
}
// Apply Frame Size Adjustment (Only to Hamwi typically, but we can display it specifically)
// Hamwi: Medium = calculated, Small = -10%, Large = +10%
var hamwiAdjusted = hamwi;
if (frame === 'small') {
hamwiAdjusted = hamwi * 0.90;
} else if (frame === 'large') {
hamwiAdjusted = hamwi * 1.10;
}
// Convert to LBS
var devineLbs = devine * 2.20462;
var robinsonLbs = robinson * 2.20462;
var millerLbs = miller * 2.20462;
var hamwiLbs = hamwiAdjusted * 2.20462;
// BMI Range (Healthy 18.5 – 24.9)
var minHealthyKg = 18.5 * (heightInMeters * heightInMeters);
var maxHealthyKg = 24.9 * (heightInMeters * heightInMeters);
var minHealthyLbs = minHealthyKg * 2.20462;
var maxHealthyLbs = maxHealthyKg * 2.20462;
// 5. Update UI
// Main Result: Average of the formulas (rounded)
// Note: We use HamwiAdjusted for the average to respect frame size choice
var avgWeight = (devineLbs + robinsonLbs + millerLbs + hamwiLbs) / 4;
document.getElementById('mainResult').innerText = Math.round(avgWeight) + " lbs";
document.getElementById('bmiRange').innerText = "Healthy BMI Range: " + Math.round(minHealthyLbs) + " – " + Math.round(maxHealthyLbs) + " lbs";
// Update Table
var tableHtml = "";
tableHtml += "
Devine
" + Math.round(devineLbs) + " lbs
Medical Dosing Standard
";
tableHtml += "
Robinson
" + Math.round(robinsonLbs) + " lbs
Devine Modification
";
tableHtml += "
Miller
" + Math.round(millerLbs) + " lbs
Modern Estimate
";
tableHtml += "
Hamwi (Adjusted)
" + Math.round(hamwiLbs) + " lbs
Considers Frame Size
";
document.getElementById('breakdownTable').innerHTML = tableHtml;
// Update Chart
drawChart(Math.round(devineLbs), Math.round(robinsonLbs), Math.round(millerLbs), Math.round(hamwiLbs), Math.round(minHealthyLbs), Math.round(maxHealthyLbs));
}
function resetCalculator() {
document.getElementById('gender').value = 'male';
document.getElementById('heightFt').value = 5;
document.getElementById('heightIn').value = 10;
document.getElementById('frameSize').value = 'medium';
calculatePerfectWeight();
}
function copyResults() {
var res = document.getElementById('mainResult').innerText;
var range = document.getElementById('bmiRange').innerText;
var text = "My Perfect Weight Calculation:\n" +
"Target: " + res + "\n" +
range + "\n" +
"Calculated using Devine, Robinson, Miller, and Hamwi formulas.";
// Create temporary element to copy
var tempInput = document.createElement("textarea");
tempInput.value = text;
document.body.appendChild(tempInput);
tempInput.select();
document.execCommand("copy");
document.body.removeChild(tempInput);
var feedback = document.getElementById('copyFeedback');
feedback.style.display = 'block';
setTimeout(function() {
feedback.style.display = 'none';
}, 2000);
}
// Canvas Chart Logic (No libraries)
function drawChart(d, r, m, h, minBMI, maxBMI) {
var canvas = document.getElementById('weightChart');
if (!canvas.getContext) return;
var ctx = canvas.getContext('2d');
var width = canvas.width; // 300 default usually, but relies on attribute
var height = canvas.height;
// Clear canvas
ctx.clearRect(0, 0, width, height);
// Responsive width fix
var rect = canvas.getBoundingClientRect();
canvas.width = rect.width;
width = rect.width;
// Data setup
var values = [d, r, m, h];
var labels = ["Devine", "Robinson", "Miller", "Hamwi"];
// Find scale (Max value to draw)
var maxVal = Math.max(d, r, m, h, maxBMI) * 1.1; // +10% padding
// Layout metrics
var barWidth = (width – 60) / 5; // spacing
var startX = 40;
var bottomY = height – 30;
var chartHeight = height – 50;
// Draw BMI Background Zone (Healthy Range)
var yMin = bottomY – (minBMI / maxVal) * chartHeight;
var yMax = bottomY – (maxBMI / maxVal) * chartHeight;
ctx.fillStyle = "rgba(40, 167, 69, 0.1)";
ctx.fillRect(startX, yMax, width – 50, yMin – yMax);
// BMI Label
ctx.fillStyle = "#28a745";
ctx.font = "10px sans-serif";
ctx.fillText("Healthy BMI Range", width – 110, yMax – 5);
// Draw Bars
for (var i = 0; i < values.length; i++) {
var val = values[i];
var barHeight = (val / maxVal) * chartHeight;
var x = startX + (i * (barWidth + 10));
var y = bottomY – barHeight;
// Bar Color
ctx.fillStyle = "#004a99";
// Draw Bar
ctx.fillRect(x, y, barWidth, barHeight);
// Draw Value on top
ctx.fillStyle = "#333";
ctx.font = "bold 12px sans-serif";
ctx.textAlign = "center";
ctx.fillText(val, x + barWidth/2, y – 5);
// Draw Label on bottom
ctx.fillStyle = "#666";
ctx.font = "11px sans-serif";
ctx.fillText(labels[i], x + barWidth/2, bottomY + 15);
}
// Draw Axes Lines
ctx.beginPath();
ctx.strokeStyle = "#ccc";
ctx.moveTo(30, bottomY);
ctx.lineTo(width, bottomY); // X axis
ctx.moveTo(30, bottomY);
ctx.lineTo(30, 10); // Y axis
ctx.stroke();
}
// Resize chart on window resize
window.onresize = function() {
calculatePerfectWeight();
};