How to Calculate Your Weight According to Height | Ideal Weight Calculator
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Estimated Ideal Weight Range
155 – 174 lbs
Based on Healthy BMI (18.5 – 24.9)
Comparison of Ideal Weight Formulas
| Formula |
Calculated Weight |
Basis |
Visual representation of your ideal weight range vs. specific formulas.
What is "How to Calculate Your Weight According to Height"?
Understanding how to calculate your weight according to height is a fundamental aspect of health monitoring and fitness planning. This calculation typically refers to determining your "Ideal Body Weight" (IBW) or finding the healthy weight range associated with your height based on the Body Mass Index (BMI) scale.
While no single number defines health, medical professionals use specific formulas to estimate a weight range that is statistically associated with lower mortality rates and better health outcomes. These calculations are useful for setting fitness goals, determining medication dosages in clinical settings, and assessing general nutritional status.
It is important to note that these calculations are estimates. They do not account for muscle mass, bone density, or body composition. An athlete with high muscle mass might be classified as "overweight" by simple height-weight charts, despite being metabolically healthy.
Formulas and Mathematical Explanation
There are several methods for how to calculate your weight according to height. The most common are the BMI method and four specific equations developed by researchers over the decades.
1. Body Mass Index (BMI) Range
The World Health Organization defines a "normal" BMI range as 18.5 to 24.9. To find the weight range for a specific height:
Min Weight = 18.5 × (Height in meters)²
Max Weight = 24.9 × (Height in meters)²
2. The Devine Formula (1974)
Originally designed for calculating drug dosages, this is the most widely used formula.
- Men: 50.0 kg + 2.3 kg per inch over 5 feet
- Women: 45.5 kg + 2.3 kg per inch over 5 feet
3. The Hamwi Formula (1964)
Popular in nutritional settings for quick estimates.
- Men: 48.0 kg + 2.7 kg per inch over 5 feet
- Women: 45.5 kg + 2.2 kg per inch over 5 feet
Variable Reference Table
| Variable |
Meaning |
Typical Unit |
| Height |
Vertical stature |
Meters / Inches |
| Base Weight |
Starting constant for 5ft height |
Kilograms (kg) |
| Increment |
Weight added per inch > 5ft |
kg / inch |
Practical Examples
Example 1: The Average Male
Profile: Male, 5 feet 10 inches (70 inches total).
Goal: Determine ideal weight using the Devine formula.
Calculation:
Base height is 60 inches (5 ft). The excess is 10 inches.
Formula: 50 kg + (2.3 kg × 10) = 50 + 23 = 73 kg.
Converted to pounds: 73 kg × 2.20462 ≈ 161 lbs.
Example 2: The Average Female
Profile: Female, 5 feet 4 inches (64 inches total).
Goal: Determine ideal weight using the Robinson formula.
Calculation:
Base height is 60 inches. The excess is 4 inches.
Formula: 49 kg + (1.7 kg × 4) = 49 + 6.8 = 55.8 kg.
Converted to pounds: 55.8 kg × 2.20462 ≈ 123 lbs.
How to Use This Calculator
- Select Your Unit: Choose between Imperial (feet/lbs) or Metric (cm/kg) based on your preference.
- Select Gender: Choose Male or Female. This adjusts the base constants in the formulas to account for biological differences in body composition.
- Enter Height: Input your height accurately. If using Imperial, separate feet and inches.
- Review Results: The calculator immediately updates. The large highlighted number is the healthy BMI range. Below it, you will see specific "Ideal Weight" points based on the Devine, Robinson, Miller, and Hamwi formulas.
- Analyze the Chart: The visual bar chart shows where these specific formula results fall within the broader healthy BMI spectrum.
Key Factors That Affect Results
When learning how to calculate your weight according to height, consider these influencing factors:
- Muscle Mass: Muscle is denser than fat. A bodybuilder may weigh significantly more than the "ideal" calculated weight but have a low body fat percentage and be very healthy.
- Bone Frame Size: The Hamwi formula is often adjusted by ±10% to account for small or large frame sizes. Larger frames naturally carry more weight.
- Age: Metabolism slows and body composition changes with age. Older adults may carry slightly more weight without adverse health effects compared to younger adults.
- Pregnancy: These calculators are not applicable for pregnant women, who have specific weight gain guidelines.
- Fat Distribution: Visceral fat (around organs) is more dangerous than subcutaneous fat. Two people of the same weight and height may have different health risks depending on where fat is stored.
- Hydration Levels: Daily weight can fluctuate by several pounds due to water retention, salt intake, and hydration status.
Frequently Asked Questions (FAQ)
1. Which formula is the most accurate?
The Devine formula is the most widely accepted for medical dosing, while the BMI range is the standard for general public health assessment. No single formula is perfect for everyone.
2. Why do the formulas give different results?
They were developed based on different population data sets and time periods. For example, the Miller formula (1983) tends to estimate lower weights than the Devine formula (1974).
3. Is BMI accurate for athletes?
Generally, no. BMI does not distinguish between muscle and fat. Athletes often have high BMIs but low body fat.
4. How do I calculate my weight for a large frame?
A common rule of thumb with the Hamwi formula is to add 10% to the result for a large frame and subtract 10% for a small frame.
5. What if I am under 5 feet tall?
Most standard IBW formulas are based on a base height of 5 feet. For heights under 5 feet, calculations often subtract weight per inch under 5 feet, but accuracy decreases.
6. Does age affect ideal weight?
Yes. Research suggests that slightly higher BMIs in older adults (over 65) may be protective against mortality, unlike in younger adults.
7. Should I aim for the exact number?
No. Treat the result as a general target range rather than a strict number. A healthy weight is a range, not a point.
8. How often should I check my weight?
Weekly weighing is often recommended to track trends without obsessing over daily fluctuations caused by water weight.
Related Tools and Resources
// Global Variables
var ctx = document.getElementById('weightChart').getContext('2d');
var chartInstance = null;
// Initialization
window.onload = function() {
calculateWeight();
};
function toggleUnits() {
var unit = document.getElementById('unitSelect').value;
var imperialInputs = document.getElementById('imperialInputs');
var metricInputs = document.getElementById('metricInputs');
var heightFt = document.getElementById('heightFt');
var heightIn = document.getElementById('heightIn');
var heightCm = document.getElementById('heightCm');
if (unit === 'imperial') {
imperialInputs.style.display = 'block';
metricInputs.style.display = 'none';
// Convert current CM to Ft/In for continuity
var totalInches = heightCm.value / 2.54;
heightFt.value = Math.floor(totalInches / 12);
heightIn.value = Math.round(totalInches % 12);
} else {
imperialInputs.style.display = 'none';
metricInputs.style.display = 'block';
// Convert current Ft/In to CM for continuity
var totalInches = (parseInt(heightFt.value) * 12) + parseInt(heightIn.value);
heightCm.value = Math.round(totalInches * 2.54);
}
calculateWeight();
}
function calculateWeight() {
var unit = document.getElementById('unitSelect').value;
var gender = document.getElementById('genderSelect').value;
var heightInches = 0;
var heightMeters = 0;
// Get Height
if (unit === 'imperial') {
var ft = parseFloat(document.getElementById('heightFt').value) || 0;
var inc = parseFloat(document.getElementById('heightIn').value) || 0;
heightInches = (ft * 12) + inc;
heightMeters = heightInches * 0.0254;
} else {
var cm = parseFloat(document.getElementById('heightCm').value) || 0;
heightMeters = cm / 100;
heightInches = cm / 2.54;
}
// Validation
if (heightInches < 12) {
// Avoid calculation on empty/invalid inputs
return;
}
// 1. BMI Range Calculation (18.5 – 24.9)
var minWeightKg = 18.5 * (heightMeters * heightMeters);
var maxWeightKg = 24.9 * (heightMeters * heightMeters);
// 2. IBW Formulas
// Base height for formulas is usually 5ft (60 inches)
var baseHeightInches = 60;
var heightDiff = heightInches – baseHeightInches;
// If height 5ft
devineKg = 50 + (2.3 * heightDiff);
// Robinson: 52kg + 1.9kg per inch > 5ft
robinsonKg = 52 + (1.9 * heightDiff);
// Miller: 56.2kg + 1.41kg per inch > 5ft
millerKg = 56.2 + (1.41 * heightDiff);
// Hamwi: 48kg + 2.7kg per inch > 5ft
hamwiKg = 48 + (2.7 * heightDiff);
} else {
// Devine: 45.5kg + 2.3kg per inch > 5ft
devineKg = 45.5 + (2.3 * heightDiff);
// Robinson: 49kg + 1.7kg per inch > 5ft
robinsonKg = 49 + (1.7 * heightDiff);
// Miller: 53.1kg + 1.36kg per inch > 5ft
millerKg = 53.1 + (1.36 * heightDiff);
// Hamwi: 45.5kg + 2.2kg per inch > 5ft
hamwiKg = 45.5 + (2.2 * heightDiff);
}
// Display Results
displayResults(unit, minWeightKg, maxWeightKg, devineKg, robinsonKg, millerKg, hamwiKg);
updateTable(unit, devineKg, robinsonKg, millerKg, hamwiKg);
drawChart(unit, minWeightKg, maxWeightKg, devineKg, robinsonKg, millerKg, hamwiKg);
}
function displayResults(unit, min, max, devine, robinson, miller, hamwi) {
var unitLabel = unit === 'imperial' ? ' lbs' : ' kg';
var factor = unit === 'imperial' ? 2.20462 : 1;
// Helper to format
function fmt(val) { return Math.round(val * factor); }
document.getElementById('mainResult').innerText = fmt(min) + " – " + fmt(max) + unitLabel;
document.getElementById('devineResult').innerText = fmt(devine) + unitLabel;
document.getElementById('robinsonResult').innerText = fmt(robinson) + unitLabel;
document.getElementById('millerResult').innerText = fmt(miller) + unitLabel;
document.getElementById('hamwiResult').innerText = fmt(hamwi) + unitLabel;
}
function updateTable(unit, devine, robinson, miller, hamwi) {
var tbody = document.getElementById('comparisonTableBody');
var unitLabel = unit === 'imperial' ? ' lbs' : ' kg';
var factor = unit === 'imperial' ? 2.20462 : 1;
function fmt(val) { return Math.round(val * factor) + unitLabel; }
var html = ";
html += '
| Devine | ' + fmt(devine) + ' | Medical Standard |
';
html += '
| Hamwi | ' + fmt(hamwi) + ' | Body Frame Focus |
';
html += '
| Robinson | ' + fmt(robinson) + ' | Population Avg (1983) |
';
html += '
| Miller | ' + fmt(miller) + ' | Population Avg (1983) |
';
tbody.innerHTML = html;
}
function drawChart(unit, min, max, devine, robinson, miller, hamwi) {
var factor = unit === 'imperial' ? 2.20462 : 1;
var unitLabel = unit === 'imperial' ? 'lbs' : 'kg';
// Convert all to display units
var dMin = min * factor;
var dMax = max * factor;
var dDevine = devine * factor;
var dHamwi = hamwi * factor;
// Canvas setup
var canvas = document.getElementById('weightChart');
var ctx = canvas.getContext('2d');
var width = canvas.width = canvas.offsetWidth;
var height = canvas.height = 150;
// Clear
ctx.clearRect(0, 0, width, height);
// Margins
var margin = 40;
var chartWidth = width – (margin * 2);
// Scale range: slightly wider than BMI range
var scaleMin = dMin * 0.8;
var scaleMax = dMax * 1.2;
var range = scaleMax – scaleMin;
function getX(val) {
return margin + ((val – scaleMin) / range) * chartWidth;
}
// Draw BMI Range Bar (Green Zone)
var xStart = getX(dMin);
var xEnd = getX(dMax);
var barHeight = 40;
var barY = 50;
ctx.fillStyle = 'rgba(40, 167, 69, 0.2)';
ctx.fillRect(xStart, barY, xEnd – xStart, barHeight);
ctx.strokeStyle = '#28a745';
ctx.strokeRect(xStart, barY, xEnd – xStart, barHeight);
// Label BMI Range
ctx.fillStyle = '#28a745′;
ctx.font = '12px Arial';
ctx.textAlign = 'center';
ctx.fillText('Healthy BMI Range', xStart + (xEnd – xStart)/2, barY – 10);
ctx.fillText(Math.round(dMin), xStart, barY + barHeight + 15);
ctx.fillText(Math.round(dMax), xEnd, barY + barHeight + 15);
// Draw Specific Formulas as vertical lines
function drawMarker(val, color, label, yOffset) {
var x = getX(val);
ctx.beginPath();
ctx.moveTo(x, barY);
ctx.lineTo(x, barY + barHeight);
ctx.strokeStyle = color;
ctx.lineWidth = 2;
ctx.stroke();
// Label
ctx.fillStyle = color;
ctx.textAlign = 'center';
ctx.fillText(label, x, barY + barHeight + yOffset);
}
drawMarker(dDevine, '#004a99', 'Devine', 30);
drawMarker(dHamwi, '#d63384', 'Hamwi', 45);
}
function resetCalculator() {
document.getElementById('heightFt').value = 5;
document.getElementById('heightIn').value = 10;
document.getElementById('heightCm').value = 178;
document.getElementById('genderSelect').value = 'male';
calculateWeight();
}
function copyResults() {
var main = document.getElementById('mainResult').innerText;
var devine = document.getElementById('devineResult').innerText;
var text = "My Ideal Weight Calculation:\n";
text += "Healthy BMI Range: " + main + "\n";
text += "Devine Formula: " + devine + "\n";
text += "Calculated at: " + window.location.href;
var tempInput = document.createElement("textarea");
tempInput.value = text;
document.body.appendChild(tempInput);
tempInput.select();
document.execCommand("copy");
document.body.removeChild(tempInput);
var btn = document.querySelector('.btn-copy');
var originalText = btn.innerText;
btn.innerText = "Copied!";
setTimeout(function(){ btn.innerText = originalText; }, 2000);
}