In the "Auto" (Automatic) door industry, determining the precise weight of a door panel is the critical first step in selecting the correct operator. Whether you are installing a swing door operator for accessibility (ADA compliance) or a sliding glass entry system for a retail store, the motor's torque and the return spring's tension must match the physical mass of the door.
Undersizing a door operator can lead to:
Motor Burnout: The engine works too hard to overcome inertia.
Safety Failures: The door may not stop or reverse correctly upon impact if the momentum is miscalculated.
Slow Operation: Inability to meet ANSI opening speed standards.
How to Calculate Door Weight
If you cannot remove the door to weigh it on a scale, you can calculate the theoretical weight using the volume of the door and the density of its material. This calculator uses the following physics formula:
The "Auto" calculation relies heavily on density. Here are common values used in the automatic door industry:
Tempered Glass (2500 kg/m³): Extremely heavy. Common in "herculite" or frameless storefront doors.
Solid Core Wood (~700-800 kg/m³): Frequently found in office builds requiring fire ratings.
Hollow Metal/Steel (7850 kg/m³): While steel is dense, these doors are usually hollow or honeycomb-filled, significantly reducing the effective weight.
Selecting the Right Automatic Operator Class
Once you have the weight, you can categorize the door to select the appropriate automation hardware:
Low Energy (Light Duty): Typically for doors under 100 lbs (45 kg). Used for residential or light traffic accessibility.
Standard Duty: For doors between 100-200 lbs (45-90 kg). The standard for most commercial ADA swing doors.
Heavy Duty: For doors exceeding 200 lbs (90 kg). Requires high-torque gearboxes, often found in industrial settings or tall glass entrances.
var currentUnit = 'metric'; // 'metric' or 'imperial'
function setUnits(unit) {
currentUnit = unit;
// Update Buttons
document.getElementById('btnMetric').className = unit === 'metric' ? 'toggle-btn active' : 'toggle-btn';
document.getElementById('btnImperial').className = unit === 'imperial' ? 'toggle-btn active' : 'toggle-btn';
// Update Labels and Placeholders
if (unit === 'metric') {
document.getElementById('labelHeight').innerText = 'Door Height (mm)';
document.getElementById('doorHeight').placeholder = 'e.g. 2100';
document.getElementById('labelWidth').innerText = 'Door Width (mm)';
document.getElementById('doorWidth').placeholder = 'e.g. 900';
document.getElementById('labelThickness').innerText = 'Door Thickness (mm)';
document.getElementById('doorThickness').placeholder = 'e.g. 40';
document.getElementById('hardwareHint').innerText = 'Enter in kg';
} else {
document.getElementById('labelHeight').innerText = 'Door Height (inches)';
document.getElementById('doorHeight').placeholder = 'e.g. 84';
document.getElementById('labelWidth').innerText = 'Door Width (inches)';
document.getElementById('doorWidth').placeholder = 'e.g. 36';
document.getElementById('labelThickness').innerText = 'Door Thickness (inches)';
document.getElementById('doorThickness').placeholder = 'e.g. 1.75';
document.getElementById('hardwareHint').innerText = 'Enter in lbs';
}
// Hide previous results if units change to avoid confusion
document.getElementById('resultArea').classList.remove('active');
}
function calculateAutoDoorWeight() {
// 1. Get Inputs
var h = document.getElementById('doorHeight').value;
var w = document.getElementById('doorWidth').value;
var t = document.getElementById('doorThickness').value;
var density = document.getElementById('doorMaterial').value;
var hardware = document.getElementById('hardwareWeight').value;
// 2. Validate
if (!h || !w || !t || !density) {
alert("Please fill in dimensions and select a material.");
return;
}
h = parseFloat(h);
w = parseFloat(w);
t = parseFloat(t);
density = parseFloat(density); // Density is always stored as kg/m^3 in the value attribute
hardware = hardware ? parseFloat(hardware) : 0;
var weightKg = 0;
var volumeM3 = 0;
// 3. Calculation Logic
if (currentUnit === 'metric') {
// Inputs are in mm. Convert to meters for calculation
var h_m = h / 1000;
var w_m = w / 1000;
var t_m = t / 1000;
volumeM3 = h_m * w_m * t_m;
var baseWeight = volumeM3 * density;
weightKg = baseWeight + hardware;
} else {
// Inputs are in inches.
// Convert inches to meters: 1 inch = 0.0254 meters
var h_m = h * 0.0254;
var w_m = w * 0.0254;
var t_m = t * 0.0254;
volumeM3 = h_m * w_m * t_m;
var baseWeight = volumeM3 * density;
// Hardware input is in lbs, convert to kg for total then convert back for display?
// Easier: Calculate everything in KG first, then convert final numbers.
var hardwareKg = hardware * 0.453592;
weightKg = baseWeight + hardwareKg;
}
// 4. Prepare Output values
var weightLbs = weightKg * 2.20462;
var volumeDisp = "";
// Display Logic
var displayWeightStr = "";
var displayBaseStr = "";
if (currentUnit === 'metric') {
volumeDisp = volumeM3.toFixed(4) + " m³";
displayBaseStr = (weightKg – hardware).toFixed(2) + " kg";
displayWeightStr = weightKg.toFixed(2) + " kg (" + weightLbs.toFixed(1) + " lbs)";
} else {
var volFt3 = volumeM3 * 35.3147;
volumeDisp = volFt3.toFixed(4) + " ft³";
var baseLbs = (weightKg * 2.20462) – hardware; // hardware was already in lbs in input
displayBaseStr = baseLbs.toFixed(2) + " lbs";
displayWeightStr = weightLbs.toFixed(2) + " lbs (" + weightKg.toFixed(1) + " kg)";
}
// 5. Update DOM
document.getElementById('resVolume').innerText = volumeDisp;
document.getElementById('resBaseWeight').innerText = displayBaseStr;
document.getElementById('resTotalWeight').innerText = displayWeightStr;
// 6. Generate Recommendation
var recText = "Operator Recommendation:";
var safeWeightKg = weightKg; // Use KG for internal logic thresholds
if (safeWeightKg < 45) {
recText += "Class: Light Duty / Low Energy. Suitable for residential or simple ADA accessibility compliance.";
} else if (safeWeightKg >= 45 && safeWeightKg < 90) {
recText += "Class: Standard Duty. Ideal for most commercial storefronts, office entries, and retail swing doors.";
} else if (safeWeightKg >= 90 && safeWeightKg < 150) {
recText += "Class: Heavy Duty. Requires a robust gearbox. Check hinge capacity and ensure pivot points are reinforced.";
} else {
recText += "Class: Extreme / Industrial Duty. This door is very heavy. Consult a structural engineer and use specialized hydraulic or high-torque electromechanical operators.";
}
if (w > 1220 && currentUnit === 'metric') { // Wider than 1220mm
recText += "Note: Door is extra wide (>1.2m). Inertia will be high. Use a heavy-duty operator regardless of weight.";
}
if (w > 48 && currentUnit === 'imperial') { // Wider than 48 inches
recText += "Note: Door is extra wide (>48in). Inertia will be high. Use a heavy-duty operator regardless of weight.";
}
document.getElementById('openerRec').innerHTML = recText;
document.getElementById('resultArea').className = "results-area active";
}