Determine your scientifically calculated ideal body weight range based on widely accepted medical formulas.
Male
Female
Gender affects formula constants due to physiological differences.
Enter your height in centimeters.
Please enter a valid height between 100cm and 300cm.
Used for general health context (18-120).
Estimated Ideal Weight Range
68.0 – 74.5 kg
Based on aggregate of medical formulas
Healthy BMI Range (18.5 – 24.9)
56.7 – 76.3 kg
Devine Formula Result
— kg
Robinson Formula Result
— kg
Formula Comparison Table
Formula Name
Calculated Weight (kg)
Year Established
Weight Distribution Analysis
Comparison of different ideal weight in kg calculator formulas vs BMI Upper Limit.
Results copied to clipboard!
What is an Ideal Weight in kg Calculator?
An ideal weight in kg calculator is a mathematical tool designed to estimate a healthy body weight based on physical characteristics such as height and gender. Unlike a simple scale which only tells you your current mass, an ideal weight calculator uses scientifically derived formulas to provide a target weight that is statistically associated with the lowest mortality rates and optimal health outcomes.
This tool is useful for individuals looking to set realistic fitness goals, medical professionals assessing patient health, and anyone monitoring their body composition. It is important to note that "ideal weight" is a statistical average; individual variations in muscle mass, bone density, and frame size mean that your personal healthy weight may differ slightly from the calculated average.
There are several misconceptions regarding these calculators. Many believe there is a single "perfect" weight, but in reality, health exists across a spectrum. That is why our ideal weight in kg calculator provides a range of values derived from multiple reputable formulas (Devine, Robinson, Miller, and Hamwi) alongside the standard Body Mass Index (BMI) range.
Ideal Weight in kg Calculator Formula and Mathematical Explanation
The calculation of ideal body weight (IBW) relies on linear equations that assume a base weight for a specific height (usually 5 feet) and add a set amount of weight for every inch over that height. Below are the specific formulas used in this calculator.
Note: In the formulas below, Height is calculated in inches over 60 inches (5 feet). Our calculator automatically converts your input from centimeters to inches.
Variables Table
Variable
Meaning
Unit
Typical Range
H
Height of the individual
Inches (converted from cm)
60 – 80 inches
Base Weight
Starting weight for 5ft height
kg
45 – 56 kg
Incr
Weight added per inch over 5ft
kg
1.4 – 2.7 kg
The Formulas
1. Devine Formula (1974): Originally developed for calculating medication dosages.
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. Robinson Formula (1983): developed to refine the Devine formula.
Men: 52.0 kg + 1.9 kg per inch over 5 feet
Women: 49.0 kg + 1.7 kg per inch over 5 feet
3. Miller Formula (1983): Often yields lower estimates for weight.
Men: 56.2 kg + 1.41 kg per inch over 5 feet
Women: 53.1 kg + 1.36 kg per inch over 5 feet
Practical Examples (Real-World Use Cases)
To understand how the ideal weight in kg calculator works in practice, let's look at two detailed examples using different profiles.
Example 1: The Average Male
Input: Male, 180 cm (approx 5ft 11in). Calculation Logic:
First, convert 180 cm to inches: 70.8 inches.
Inches over 5ft = 10.8.
Devine: 50 + (2.3 × 10.8) = 74.8 kg
Robinson: 52 + (1.9 × 10.8) = 72.5 kg
BMI Range (18.5-24.9): 60.0 kg to 80.7 kg
Interpretation: For this individual, a weight around 72-75 kg is statistically ideal, but anywhere between 60 kg and 80 kg is considered medically healthy via BMI.
Example 2: The Petite Female
Input: Female, 160 cm (approx 5ft 3in). Calculation Logic:
Convert 160 cm to inches: 63.0 inches.
Inches over 5ft = 3.0.
Devine: 45.5 + (2.3 × 3.0) = 52.4 kg
Miller: 53.1 + (1.36 × 3.0) = 57.2 kg
BMI Range: 47.4 kg to 63.7 kg
Interpretation: The Miller formula suggests a higher weight than Devine for this height. The user might aim for a range between 52 kg and 57 kg as their target zone using the ideal weight in kg calculator.
How to Use This Ideal Weight in kg Calculator
Using this tool is straightforward, but accuracy depends on correct inputs.
Select Gender: Choose Male or Female. This is critical as biological males and females have different baseline muscle and bone mass distributions accounted for in the formulas.
Enter Height: Input your height in centimeters. If you only know your height in feet/inches, multiply feet by 30.48 and inches by 2.54 to get centimeters.
Enter Age: While the core formulas (Devine, Robinson) are age-independent, age is useful for context. Older adults may benefit from being slightly on the heavier side of the "ideal" range to protect against frailty.
Review Results: Look at the "Estimated Ideal Weight Range." This aggregates the formulas. Check the comparison table to see how different medical standards evaluate your height.
Key Factors That Affect Ideal Weight Results
While the ideal weight in kg calculator provides a mathematical baseline, several real-world factors influence what your true "ideal" weight should be.
Muscle Mass: Muscle 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 Structure (Frame Size): Individuals with larger wrist and ankle circumferences (large frame) naturally weigh more. Most formulas assume a medium frame; add 10% for large frames or subtract 10% for small frames.
Age: Metabolism slows with age. While the formulas don't change, the "healthy" target might shift. Slightly higher weight in senior years can provide a buffer against illness.
Pregnancy and Lactation: This calculator is not applicable for pregnant or breastfeeding women, as weight gain is physiological and necessary.
Body Fat Distribution: Visceral fat (around organs) is riskier than subcutaneous fat. Two people can have the same "ideal weight" but different health risks based on where fat is stored.
Hydration Levels: Daily weight can fluctuate by 1-2 kg based on water retention, salt intake, and hydration, affecting daily comparisons to the ideal target.
Frequently Asked Questions (FAQ)
Is the ideal weight in kg calculator 100% accurate for everyone?
No calculator can account for every individual variable. It provides a statistical estimation based on population averages. Athletes, bodybuilders, and pregnant women should not rely solely on these results.
Which formula is the best to use?
The Devine formula is the most widely used in medical settings for dosing. However, the Robinson and Miller formulas were created to improve accuracy for modern populations. Using the average of all three gives a balanced view.
Why does the result differ from BMI?
BMI (Body Mass Index) provides a broad range (e.g., 18.5-24.9) based purely on mass vs. height. The Ideal Weight formulas (Devine, etc.) attempt to pinpoint a specific target number, often landing near the middle of the BMI range.
Should I lose weight to match the calculator exactly?
Not necessarily. If you are within the healthy BMI range and have good metabolic markers (blood pressure, sugar, lipids), chasing a specific "ideal" number is often unnecessary. Consult a doctor before starting a weight loss plan.
How do I adjust for frame size?
A common rule of thumb is to adjust the result by 10%. If you have a large frame, add 10% to the calculator's result. If you have a small frame, subtract 10%.
Does age affect the calculation?
The mathematical formulas (Devine, Hamwi) do not include an age variable. However, medical advice regarding weight often changes with age, with slightly higher weights being acceptable for those over 65.
What is the Hamwi formula?
The Hamwi formula is one of the oldest and simplest "rule of thumb" methods: 106 lbs for the first 5ft + 6 lbs per inch for men, and 100 lbs + 5 lbs per inch for women.
Can children use this calculator?
No. Children and adolescents are still growing, and their weight-to-height ratio changes rapidly. They should use CDC growth charts or pediatric specific percentiles, not adult ideal weight formulas.
Related Tools and Internal Resources
BMI Calculator – Calculate your Body Mass Index score to check if you are underweight, normal, or overweight.
// Initialize calculator logic
function calculateIdealWeight() {
// Get Inputs
var gender = document.getElementById('gender').value;
var heightCm = parseFloat(document.getElementById('heightCm').value);
var age = parseInt(document.getElementById('age').value);
// Validation
var heightError = document.getElementById('heightError');
if (isNaN(heightCm) || heightCm 300) {
heightError.style.display = 'block';
return; // Stop calculation
} else {
heightError.style.display = 'none';
}
// Conversions
// 1 inch = 2.54 cm
// Base is 5ft = 60 inches
var heightInches = heightCm / 2.54;
var inchesOver60 = heightInches – 60;
// If height is under 5ft, we treat inchesOver60 as negative for the linear equation,
// though strictly these formulas are meant for adults > 5ft.
// We will allow the linear math to proceed but clamp negative results to reasonable minimums if needed.
// Formulas
var devine = 0;
var robinson = 0;
var miller = 0;
var hamwi = 0;
if (gender === 'male') {
devine = 50.0 + (2.3 * inchesOver60);
robinson = 52.0 + (1.9 * inchesOver60);
miller = 56.2 + (1.41 * inchesOver60);
hamwi = 48.0 + (2.7 * inchesOver60);
} else {
devine = 45.5 + (2.3 * inchesOver60);
robinson = 49.0 + (1.7 * inchesOver60);
miller = 53.1 + (1.36 * inchesOver60);
hamwi = 45.5 + (2.2 * inchesOver60);
}
// BMI Calculation (Healthy Range 18.5 – 24.9)
var heightMeters = heightCm / 100;
var minBmiWeight = 18.5 * (heightMeters * heightMeters);
var maxBmiWeight = 24.9 * (heightMeters * heightMeters);
// Sanity Check for very short heights (prevent negative weights)
// Though input validation > 100cm prevents extreme negatives.
// Format Results
var devineStr = devine.toFixed(1);
var robinsonStr = robinson.toFixed(1);
var millerStr = miller.toFixed(1);
var hamwiStr = hamwi.toFixed(1);
var minBmiStr = minBmiWeight.toFixed(1);
var maxBmiStr = maxBmiWeight.toFixed(1);
// Update DOM – Intermediate
document.getElementById('devineResult').innerText = devineStr + " kg";
document.getElementById('robinsonResult').innerText = robinsonStr + " kg";
document.getElementById('bmiWeightRange').innerText = minBmiStr + " – " + maxBmiStr + " kg";
// Calculate Primary Result (Average of Devine and Robinson – widely used)
// Or simply display a tight range based on the formulas
var formulas = [devine, robinson, miller, hamwi];
var minFormula = Math.min.apply(null, formulas);
var maxFormula = Math.max.apply(null, formulas);
document.getElementById('primaryResult').innerText = minFormula.toFixed(1) + " – " + maxFormula.toFixed(1) + " kg";
document.getElementById('primaryFormula').innerText = "Range based on Devine, Robinson, Miller & Hamwi";
// Update Table
var tableHtml = ";
tableHtml += '
Devine
' + devineStr + '
1974
';
tableHtml += '
Robinson
' + robinsonStr + '
1983
';
tableHtml += '
Miller
' + millerStr + '
1983
';
tableHtml += '
Hamwi
' + hamwiStr + '
1964
';
document.getElementById('resultTableBody').innerHTML = tableHtml;
// Draw Chart
drawChart(devine, robinson, miller, hamwi, maxBmiWeight);
}
function drawChart(devine, robinson, miller, hamwi, bmiMax) {
var container = document.getElementById('chartContainer');
var width = container.offsetWidth – 40; // padding
var height = 260; // internal height
// Determine Max Scale
var maxValue = Math.max(devine, robinson, miller, hamwi, bmiMax) * 1.1;
// Data points
var data = [
{ label: 'Devine', value: devine, color: '#004a99' },
{ label: 'Robinson', value: robinson, color: '#003366' },
{ label: 'Miller', value: miller, color: '#28a745' },
{ label: 'Hamwi', value: hamwi, color: '#17a2b8' },
{ label: 'BMI Max', value: bmiMax, color: '#6c757d' }
];
var barWidth = (width / data.length) – 20;
var svgContent = ";
// Background lines
svgContent += ";
for (var i = 0; i < data.length; i++) {
var item = data[i];
var barHeight = (item.value / maxValue) * height;
var x = i * (width / data.length) + 10;
var y = height – barHeight;
// Bar
svgContent += '';
// Text Value
svgContent += " + Math.round(item.value) + ";
// Text Label
svgContent += " + item.label + ";
}
svgContent += ";
container.innerHTML = svgContent;
}
function resetCalculator() {
document.getElementById('gender').value = 'male';
document.getElementById('heightCm').value = 175;
document.getElementById('age').value = 30;
calculateIdealWeight();
}
function copyResults() {
var range = document.getElementById('primaryResult').innerText;
var bmi = document.getElementById('bmiWeightRange').innerText;
var height = document.getElementById('heightCm').value;
var gender = document.getElementById('gender').value;
var textToCopy = "Ideal Weight Calculation:\n";
textToCopy += "Profile: " + gender + ", " + height + "cm\n";
textToCopy += "Ideal Weight Range: " + range + "\n";
textToCopy += "Healthy BMI Range: " + bmi + "\n";
textToCopy += "Generated by Ideal Weight in kg Calculator";
var textArea = document.createElement("textarea");
textArea.value = textToCopy;
document.body.appendChild(textArea);
textArea.select();
document.execCommand("Copy");
textArea.remove();
var feedback = document.getElementById('copyFeedback');
feedback.style.display = 'block';
setTimeout(function() {
feedback.style.display = 'none';
}, 2000);
}
// Run on load
window.onload = function() {
calculateIdealWeight();
// Add resize listener for chart
window.addEventListener('resize', calculateIdealWeight);
};