Select the material to automatically apply density.
The outer dimension of the square tube.
Must be greater than 0.
Thickness of the tube wall.
Thickness cannot exceed half the side length.
Total length of the tube.
Price per unit of weight (e.g., $/kg or $/lb).
Total Estimated Weight
0.00kg
Weight per Meter/Foot
–
Cross-Sectional Area
–
Total Estimated Cost
–
Calculation Basis: Weight = (Outer Area – Inner Area) × Length × Density.
Using geometric subtraction method.
Figure 1: Weight comparison of your selected tube vs. other common materials.
Parameter
Value
Unit
What is "How to Calculate Weight of Square Tube"?
Understanding how to calculate weight of square tube is a fundamental skill in structural engineering, metal fabrication, and logistics. Whether you are estimating shipping costs for a construction project or determining the structural load on a beam, knowing the precise weight of hollow structural sections (HSS) is critical.
The weight of a square tube is derived from its volume and the density of the material used (such as steel, aluminum, or brass). Unlike solid bars, square tubes have a hollow interior, which significantly reduces their weight while maintaining high torsional rigidity. This efficiency makes them a staple in modern construction.
This calculator is designed for engineers, fabricators, and procurement managers who need accurate weight estimations to budget for materials and plan for transport. It eliminates the need for manual look-up tables by applying physics-based formulas directly to your custom dimensions.
Square Tube Weight Formula and Mathematical Explanation
To understand how to calculate weight of square tube manually, you must determine the volume of material in the tube's wall and multiply it by the material's density.
The Core Formula
Weight (W) = Volume (V) × Density (ρ)
Where Volume is calculated as:
V = (Areaouter – Areainner) × Length (L)
Step-by-Step Derivation
Calculate Outer Area (Aout): Square the outer side length ($S$). $A_{out} = S^2$
Calculate Inner Area (Ain): Determine the inner side length by subtracting two wall thicknesses ($t$) from the outer side. $S_{in} = S – 2t$ $A_{in} = (S – 2t)^2$
Calculate Cross-Sectional Area (A): Subtract the inner area from the outer area. $A = A_{out} – A_{in}$
Calculate Volume: Multiply the cross-sectional area by the length of the tube.
Calculate Final Weight: Multiply the volume by the specific density of the material.
Variables Table
Variable
Meaning
Metric Unit
Imperial Unit
S
Side Length (Outer)
mm
inches
t
Wall Thickness
mm
inches
L
Length
meters
feet
ρ (Rho)
Density
kg/m³
lb/ft³
Practical Examples (Real-World Use Cases)
Example 1: Steel Construction Column
A contractor needs to know how to calculate weight of square tube for a support column. The tube is Mild Steel, 100mm x 100mm with a 5mm wall thickness, and is 6 meters long.
Financial Interpretation: If steel costs $1.50 per kg, this single beam costs approximately $134.23.
Example 2: Aluminum Frame for Aerospace
An engineer is designing a lightweight frame using 2×2 inch Aluminum 6061 tubing with 0.125 inch wall thickness. The length is 10 feet.
Material: Aluminum (Density ~168.5 lb/ft³)
Area Calculation: $(2^2 – (2 – 0.25)^2) / 144$ (converting sq inches to sq feet)
Result: The calculator would show approximately 11.0 lbs for this tube.
How to Use This Square Tube Weight Calculator
Follow these steps to get an instant estimation:
Select Unit System: Choose between Metric (mm/kg) or Imperial (in/lb) based on your blueprints.
Choose Material: Select the material from the dropdown. This sets the density variable automatically (e.g., Steel is set to ~7850 kg/m³).
Enter Dimensions: Input the Side Length and Wall Thickness. Ensure the wall thickness is less than half the side length.
Enter Length & Quantity: Input the total length of the tube and how many pieces you require.
Optional Cost: If you know the current market price per kg or lb, enter it to get a total cost estimate.
Key Factors That Affect Square Tube Weight Results
When learning how to calculate weight of square tube, consider these six factors that influence the final number:
Material Density: This is the most significant factor. Steel is nearly three times heavier than aluminum. Using the wrong density value will result in massive errors.
Corner Radius: Real-world square tubes have rounded corners (radii). The theoretical formula assumes sharp corners. Actual tubes are slightly lighter (about 1-3%) than the sharp-corner calculation because material is missing from the corners.
Manufacturing Tolerances: ASTM and ISO standards allow for slight variations in wall thickness. A tube sold as "5mm wall" might actually be 4.8mm or 5.2mm, affecting the total weight.
Surface Coatings: Galvanization, painting, or powder coating adds weight. While negligible for small pieces, heavy galvanization can add 3-5% to the weight of large steel structures.
Temperature: While thermal expansion affects dimensions, it rarely affects weight significantly unless extreme precision is required in scientific applications.
Scrap and Waste: If you are calculating weight for purchasing, always account for the "kerf" (material lost during cutting) and unusable offcuts.
Frequently Asked Questions (FAQ)
Does this calculator account for rounded corners?
This calculator uses the geometric subtraction method (Sharp Corners). For most construction and logistics applications, this provides a safe "upper bound" estimate. Actual tubes with rounded corners will be slightly lighter.
What is the density of mild steel used here?
We use the standard industry average of 7850 kg/m³ (or roughly 490 lb/ft³) for mild steel.
How do I calculate the weight of a hollow rectangular tube?
The logic is similar, but instead of $S^2$, you calculate $Width \times Height$. This tool is specifically for square profiles where width equals height.
Why is the wall thickness limited?
The wall thickness cannot exceed half the side length because, mathematically, the hole in the middle would disappear, turning it into a solid bar.
Can I use this for plastic or wood tubes?
Yes, but you must know the density of your specific plastic or wood. Since these vary wildly, this calculator focuses on metals, but the volume logic remains the same.
How accurate is the cost estimation?
The cost is a direct multiplication of Weight × Price/Unit. It does not account for taxes, shipping fees, or volume discounts.
What is the difference between HSS and standard tubing?
HSS (Hollow Structural Sections) often have tighter tolerances and specific rounded corner requirements compared to standard ornamental tubing, affecting the precise weight slightly.
Is stainless steel heavier than regular steel?
Slightly. Stainless steel (grade 304) has a density of roughly 7900 kg/m³, while mild steel is 7850 kg/m³. The difference is small but adds up in large quantities.
Related Tools and Internal Resources
Expand your engineering toolkit with these related calculators:
// Global Variables
var chartInstance = null;
// Initialization
window.onload = function() {
// Set default values
document.getElementById('sideLength').value = 50;
document.getElementById('wallThick').value = 3;
document.getElementById('length').value = 6;
calculate();
};
function updateLabels() {
var system = document.getElementById('unitSystem').value;
var labelSide = document.getElementById('labelSide');
var labelWall = document.getElementById('labelWall');
var labelLength = document.getElementById('labelLength');
var labelCost = document.getElementById('labelCost');
var sideInput = document.getElementById('sideLength');
var wallInput = document.getElementById('wallThick');
var lenInput = document.getElementById('length');
if (system === 'metric') {
labelSide.innerText = "Side Length (mm)";
labelWall.innerText = "Wall Thickness (mm)";
labelLength.innerText = "Tube Length (m)";
labelCost.innerText = "Material Cost ($/kg)";
sideInput.placeholder = "e.g., 50";
wallInput.placeholder = "e.g., 3";
lenInput.placeholder = "e.g., 6";
} else {
labelSide.innerText = "Side Length (inches)";
labelWall.innerText = "Wall Thickness (inches)";
labelLength.innerText = "Tube Length (feet)";
labelCost.innerText = "Material Cost ($/lb)";
sideInput.placeholder = "e.g., 2";
wallInput.placeholder = "e.g., 0.125";
lenInput.placeholder = "e.g., 20";
}
calculate();
}
function calculate() {
// 1. Get Inputs
var system = document.getElementById('unitSystem').value;
var density = parseFloat(document.getElementById('material').value); // kg/m3
var side = parseFloat(document.getElementById('sideLength').value);
var wall = parseFloat(document.getElementById('wallThick').value);
var length = parseFloat(document.getElementById('length').value);
var qty = parseFloat(document.getElementById('quantity').value) || 1;
var costPerUnit = parseFloat(document.getElementById('cost').value) || 0;
// 2. Validation
var errSide = document.getElementById('errSide');
var errWall = document.getElementById('errWall');
var isValid = true;
if (isNaN(side) || side <= 0) {
errSide.style.display = "block";
isValid = false;
} else {
errSide.style.display = "none";
}
if (isNaN(wall) || wall = side / 2) {
errWall.style.display = "block";
isValid = false;
} else {
errWall.style.display = "none";
}
if (!isValid || isNaN(length)) {
resetResults();
return;
}
// 3. Calculation Logic
var weight = 0;
var area = 0; // Cross sectional area
var volume = 0;
var weightPerLen = 0;
if (system === 'metric') {
// Inputs: side(mm), wall(mm), length(m), density(kg/m3)
// Convert mm to m
var sideM = side / 1000;
var wallM = wall / 1000;
var innerSideM = sideM – (2 * wallM);
var areaOuter = sideM * sideM;
var areaInner = innerSideM * innerSideM;
area = areaOuter – areaInner; // m2
volume = area * length; // m3
weight = volume * density * qty; // kg
weightPerLen = (area * density); // kg/m
// Display Units
document.getElementById('weightUnit').innerText = "kg";
document.getElementById('crossArea').innerText = (area * 1000000).toFixed(2) + " mm²";
document.getElementById('weightPerUnit').innerText = weightPerLen.toFixed(3) + " kg/m";
} else {
// Inputs: side(in), wall(in), length(ft), density(kg/m3 -> need lb/ft3)
// Density conversion: 1 kg/m3 = 0.062428 lb/ft3
var densityLbFt3 = density * 0.062428;
// Convert inches to feet for volume calc
var sideFt = side / 12;
var wallFt = wall / 12;
var innerSideFt = sideFt – (2 * wallFt);
var areaOuter = sideFt * sideFt;
var areaInner = innerSideFt * innerSideFt;
area = areaOuter – areaInner; // ft2
volume = area * length; // ft3
weight = volume * densityLbFt3 * qty; // lbs
weightPerLen = (area * densityLbFt3); // lb/ft
// Display Units
document.getElementById('weightUnit').innerText = "lbs";
document.getElementById('crossArea').innerText = (area * 144).toFixed(3) + " in²";
document.getElementById('weightPerUnit').innerText = weightPerLen.toFixed(3) + " lb/ft";
}
var totalCost = weight * costPerUnit;
// 4. Update DOM
document.getElementById('totalWeight').innerText = weight.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalCost').innerText = costPerUnit > 0 ? "$" + totalCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}) : "-";
updateTable(side, wall, length, qty, weight, system);
drawChart(weight, system, volume, qty);
}
function resetResults() {
document.getElementById('totalWeight').innerText = "0.00";
document.getElementById('weightPerUnit').innerText = "-";
document.getElementById('crossArea').innerText = "-";
document.getElementById('totalCost').innerText = "-";
}
function updateTable(side, wall, length, qty, weight, system) {
var tbody = document.getElementById('tableBody');
var unitLen = system === 'metric' ? 'm' : 'ft';
var unitDim = system === 'metric' ? 'mm' : 'in';
var unitWt = system === 'metric' ? 'kg' : 'lbs';
var html = "";
html += "
Dimensions
" + side + " x " + side + " x " + wall + "
" + unitDim + "
";
html += "
Total Length
" + (length * qty).toFixed(2) + "
" + unitLen + "
";
html += "
Total Weight
" + weight.toFixed(2) + "
" + unitWt + "
";
tbody.innerHTML = html;
}
function drawChart(currentWeight, system, volume, qty) {
var canvas = document.getElementById('weightChart');
var ctx = canvas.getContext('2d');
// Handle High DPI
var dpr = window.devicePixelRatio || 1;
var rect = canvas.getBoundingClientRect();
canvas.width = rect.width * dpr;
canvas.height = rect.height * dpr;
ctx.scale(dpr, dpr);
// Clear
ctx.clearRect(0, 0, rect.width, rect.height);
// Data Preparation
// Compare current material vs others
// Densities (kg/m3): Steel 7850, Al 2700, SS 7900
var volM3 = system === 'metric' ? volume : volume / 35.315; // convert ft3 to m3 if needed for ratio
// Calculate weights for comparison (always in current unit system)
// If system is imperial, we derived weight already.
// Ratio: Al is ~34% of Steel. SS is ~101% of Steel.
// Base density reference (Steel)
var baseWeight = currentWeight;
var matVal = document.getElementById('material').value;
// Calculate hypothetical weights
// Factor = TargetDensity / CurrentDensity
var wSteel = currentWeight * (7850 / matVal);
var wAlum = currentWeight * (2700 / matVal);
var wSS = currentWeight * (7900 / matVal);
var data = [
{ label: "Aluminum", val: wAlum, color: "#6c757d" },
{ label: "Steel (Mild)", val: wSteel, color: "#004a99" },
{ label: "Stainless", val: wSS, color: "#28a745" }
];
var maxVal = Math.max(wSteel, wAlum, wSS) * 1.2;
var barWidth = 60;
var gap = 40;
var startX = 50;
var chartHeight = rect.height – 60; // bottom margin for labels
var startY = rect.height – 30;
// Draw Bars
ctx.font = "12px sans-serif";
ctx.textAlign = "center";
for (var i = 0; i < data.length; i++) {
var h = (data[i].val / maxVal) * (chartHeight – 40); // -40 for top margin
var x = startX + (i * (barWidth + gap));
var y = startY – h;
// Bar
ctx.fillStyle = data[i].color;
ctx.fillRect(x, y, barWidth, h);
// Label (Bottom)
ctx.fillStyle = "#333";
ctx.fillText(data[i].label, x + barWidth/2, startY + 15);
// Value (Top)
ctx.fillStyle = "#000";
ctx.fillText(Math.round(data[i].val) + (system==='metric'?' kg':' lbs'), x + barWidth/2, y – 5);
}
// Axis Line
ctx.beginPath();
ctx.moveTo(40, startY);
ctx.lineTo(rect.width – 20, startY);
ctx.strokeStyle = "#ccc";
ctx.stroke();
}
function resetCalc() {
document.getElementById('sideLength').value = "";
document.getElementById('wallThick').value = "";
document.getElementById('length').value = "";
document.getElementById('quantity').value = "1";
document.getElementById('cost').value = "";
resetResults();
var canvas = document.getElementById('weightChart');
var ctx = canvas.getContext('2d');
ctx.clearRect(0, 0, canvas.width, canvas.height);
document.getElementById('tableBody').innerHTML = "";
}
function copyResults() {
var w = document.getElementById('totalWeight').innerText;
var u = document.getElementById('weightUnit').innerText;
var c = document.getElementById('totalCost').innerText;
var s = document.getElementById('sideLength').value;
var wa = document.getElementById('wallThick').value;
var text = "Square Tube Calculation:\n";
text += "Dimensions: " + s + " x " + s + " / Wall: " + wa + "\n";
text += "Total Weight: " + w + " " + u + "\n";
text += "Estimated Cost: " + c;
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);
}