How to Calculate Your Weight: Ideal Body Weight & Calculator
Determine your scientifically calculated ideal body weight using recognized medical formulas.
Compare results from Devine, Robinson, Miller, and Hamwi methods to find a healthy target range.
Ideal Body Weight Calculator
Enter your details below to calculate your estimated ideal weight range.
Male
Female
Formulas differ significantly based on biological sex.
Most accurate for heights over 5 feet (60 inches).
Please enter a valid height.
Used to compare against calculated ideal targets.
Please enter a positive weight value.
Ideal Body Weight (Devine Formula)
165.3 lbs
Based on standard medical height-weight calculation.
Formula Comparisons
Robinson Formula— lbs
Miller Formula— lbs
Hamwi Formula— lbs
Healthy BMI Range— lbs
Detailed Analysis
Method
Result (lbs)
Result (kg)
Difference from Current
Table 1: Comparison of different ideal weight calculation methods and your current variance.
Visual comparison of your Current Weight vs. Calculated Ideal Formulas
What is How to Calculate Your Weight?
When people search for how to calculate your weight, they are typically looking for a method to determine their "Ideal Body Weight" (IBW). Unlike stepping on a scale, which tells you your mass due to gravity, calculating your weight involves using mathematical formulas derived from medical statistics to estimate a healthy weight target for your height and gender.
These calculations are essential tools for healthcare professionals, dietitians, and individuals setting fitness goals. While no single number defines health, having a calculated baseline helps in assessing nutritional needs and medication dosages.
However, there are common misconceptions. A calculated ideal weight is a statistical average, not a strict biological mandate. It does not account for muscle mass, bone density, or age—factors that we will explore later in this guide.
Ideal Body Weight Formulas and Mathematical Explanation
Over the last century, several formulas have been developed to standardize how to calculate your weight targets. The most widely used is the Devine Formula, originally created to calculate dosages for medications like gentamicin.
1. The Devine Formula (1974)
This is the standard used in many hospitals.
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)
A modification of Devine's formula based on later datasets.
Men: 52 kg + 1.9 kg per inch over 5 feet.
Women: 49 kg + 1.7 kg per inch over 5 feet.
Variable Definitions
Variable
Meaning
Unit
Typical Range
Height
Vertical stature
Inches / cm
60 – 84 inches
Base Weight
Starting constant
kg
45.5 – 56.2 kg
Increment
Weight added per unit of height
kg/inch
1.41 – 2.7 kg
Table 2: Key mathematical variables used in IBW formulas.
Practical Examples (Real-World Use Cases)
Example 1: The Average Male
Consider a male who is 5 feet 10 inches tall (70 inches total). To figure out how to calculate your weight using the Devine method:
Base height is 60 inches. Excess height is 10 inches.
Calculation: 50 kg + (2.3 kg × 10) = 50 + 23 = 73 kg.
Converted to pounds: 73 × 2.20462 ≈ 161 lbs.
Interpretation: A healthy target weight for this individual is approximately 161 lbs.
Example 2: The Petite Female
Consider a female who is 5 feet 2 inches tall (62 inches total). Using the Robinson formula:
Excess height is 2 inches.
Calculation: 49 kg + (1.7 kg × 2) = 49 + 3.4 = 52.4 kg.
Converted to pounds: 52.4 × 2.20462 ≈ 115.5 lbs.
Interpretation: The Robinson formula suggests a slightly lower target than Devine for this height, highlighting the importance of looking at a range of results.
How to Use This Calculator
Our tool simplifies the math. Here is a step-by-step guide on using the calculator effectively:
Select Gender: Choose Male or Female. This adjusts the base weight constant in the algorithm.
Enter Height: Input your height in feet and inches. If you are exactly 5 feet, enter 0 inches.
Input Current Weight (Optional): Entering your current weight allows the tool to calculate the variance—how far you are from the statistical ideal.
Review Results: Look at the "Primary Result" for the Devine standard, but check the "Formula Comparisons" to see a broader range.
Use the "Copy Results" button to save your data for a consultation with a nutritionist.
Key Factors That Affect Weight Results
When learning how to calculate your weight, you must understand that formulas are imperfect. Several biological factors influence what your true "ideal" weight should be:
Muscle Mass: Muscle is denser than fat. An athlete may weigh significantly more than the IBW formula suggests but have a low body fat percentage and be perfectly healthy.
Frame Size: People with larger skeletal structures (broad shoulders, thick wrists) naturally weigh more. The formulas above assume a medium frame. Small frames should subtract 10%, and large frames add 10%.
Age: Metabolic rate slows with age, and body composition changes. Older adults may carry slightly more weight without adverse health effects compared to younger adults.
Bone Density: Genetic variances in bone density contribute to total mass. High bone density increases the scale reading without increasing fat mass.
Hydration Levels: Water weight can fluctuate by several pounds daily. A calculation is a static target, while your actual weight is dynamic.
Health Conditions: Certain conditions require higher or lower weight targets. Always prioritize medical advice over a generic calculator.
Frequently Asked Questions (FAQ)
1. Is BMI better than Ideal Body Weight formulas?
They serve different purposes. BMI is a screening tool for risk categories (underweight, obese), while IBW gives a specific weight target. Both have limitations regarding muscle mass.
2. Why do different formulas give different results?
They were developed in different decades using different population data. Devine is often used for medication dosing, while Miller and Robinson are sometimes preferred for nutritional estimates.
3. Does this calculator work for children?
No. These formulas are strictly for adults (age 18+). Children require growth charts that account for developmental stages.
4. What if I am shorter than 5 feet?
Most IBW formulas start at 60 inches (5 feet). For heights below this, a common rule of thumb is to subtract 2-5 lbs for every inch under 5 feet, though accuracy decreases.
5. How accurate is the Devine formula?
It is widely accepted in the medical community but is still an estimation. It does not scan your body composition.
6. Should I diet to reach this number?
Not necessarily. If you are muscular or healthy at a higher weight, forcing yourself down to a statistical average can be harmful. Focus on body composition and blood markers.
7. How does gender affect the calculation?
Biologically, men generally have more lean muscle mass and heavier skeletons than women of the same height, which is why the male formulas start with a higher base weight.
8. Can I use this for bodybuilding?
Bodybuilders should ignore IBW formulas and BMI, as these tools will almost always classify them as "overweight" due to high muscle mass.
Related Tools and Internal Resources
Explore more tools to manage your health and finances:
TDEE Calculator – Total Daily Energy Expenditure estimation.
// INITIALIZATION
document.addEventListener("DOMContentLoaded", function() {
calculateWeight();
});
function calculateWeight() {
// 1. GET INPUTS
var gender = document.getElementById("gender").value;
var ft = parseFloat(document.getElementById("heightFt").value);
var inch = parseFloat(document.getElementById("heightIn").value);
var currentWeightLbs = parseFloat(document.getElementById("currentWeight").value);
// 2. VALIDATION
var heightError = document.getElementById("height-error");
var weightError = document.getElementById("weight-error");
var valid = true;
if (isNaN(ft) || ft < 1 || isNaN(inch) || inch < 0) {
heightError.style.display = "block";
valid = false;
} else {
heightError.style.display = "none";
}
if (isNaN(currentWeightLbs) || currentWeightLbs <= 0) {
weightError.style.display = "block";
// We can continue calculation without current weight, just can't show diff
} else {
weightError.style.display = "none";
}
if (!valid) return;
// 3. CORE LOGIC
// Convert total height to inches
var totalInches = (ft * 12) + inch;
var baseHeight = 60; // 5 feet
var diff = totalInches – baseHeight;
// If height lbsDevine ? "(Over)" : "(Under)");
var rows = [
{ name: "Devine (Medical Std)", lbs: lbsDevine, kg: wDevine },
{ name: "Robinson (1983)", lbs: lbsRobinson, kg: wRobinson },
{ name: "Miller (1983)", lbs: lbsMiller, kg: wMiller },
{ name: "Hamwi (1964)", lbs: lbsHamwi, kg: wHamwi }
];
var html = "";
for (var i = 0; i 0 ? "+" + dVal : dVal;
}
html += "
";
html += "
" + r.name + "
";
html += "
" + r.lbs.toFixed(1) + "
";
html += "
" + r.kg.toFixed(1) + "
";
html += "
" + dLabel + "
";
html += "
";
}
tableBody.innerHTML = html;
// 5. RENDER CHART
renderChart(currentWeightLbs, lbsDevine, lbsMin, lbsMax);
}
function renderChart(current, ideal, minH, maxH) {
var canvas = document.getElementById("weightChart");
var ctx = canvas.getContext("2d");
var width = canvas.width;
var height = canvas.height;
// Clear
ctx.clearRect(0, 0, width, height);
// Data Prep
// We will draw a horizontal bar chart
var labels = ["Current Weight", "Ideal (Devine)", "Healthy Max"];
// Handle missing current weight
var currentVal = isNaN(current) ? 0 : current;
var values = [currentVal, ideal, maxH];
var colors = ["#6c757d", "#004a99", "#28a745"];
if (isNaN(current)) {
// Shift if no current weight
labels.shift(); values.shift(); colors.shift();
}
var maxVal = Math.max(currentVal, maxH) * 1.2;
var barHeight = 40;
var gap = 30;
var startY = 30;
var startX = 120; // Room for text
ctx.font = "14px Arial";
ctx.fillStyle = "#333″;
for (var i = 0; i 50) {
ctx.fillText(values[i].toFixed(0) + " lbs", startX + barW – 50, y + (barHeight/2) + 5);
} else {
ctx.fillStyle = "#333″;
ctx.fillText(values[i].toFixed(0) + " lbs", startX + barW + 5, y + (barHeight/2) + 5);
}
}
// Draw Healthy Range Region
// Overlay a transparent green box to show healthy BMI range on the 'Healthy Max' line or separate?
// Let's keep it simple bars as per logic above.
}
function resetCalculator() {
document.getElementById("gender").value = "male";
document.getElementById("heightFt").value = 5;
document.getElementById("heightIn").value = 9;
document.getElementById("currentWeight").value = 180;
calculateWeight();
}
function copyResults() {
var mainRes = document.getElementById("mainResult").innerText;
var range = document.getElementById("bmiRangeResult").innerText;
var ft = document.getElementById("heightFt").value;
var inc = document.getElementById("heightIn").value;
var text = "My Weight Calculation Summary:\n";
text += "Height: " + ft + "ft " + inc + "in\n";
text += "Ideal Body Weight (Devine): " + mainRes + "\n";
text += "Healthy BMI Range: " + range + "\n";
text += "Calculated via 'How to Calculate Your Weight' Tool";
navigator.clipboard.writeText(text).then(function() {
var btn = document.querySelector(".btn-copy");
var original = btn.innerText;
btn.innerText = "Copied!";
setTimeout(function(){ btn.innerText = original; }, 2000);
});
}