.concrete-calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.calc-box {
background: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
margin-bottom: 40px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-title {
text-align: center;
margin-top: 0;
color: #2c3e50;
font-size: 24px;
margin-bottom: 25px;
font-weight: 700;
}
.input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
font-size: 14px;
color: #495057;
}
.input-group input, .input-group select {
width: 100%;
padding: 10px 12px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #80bdff;
outline: none;
box-shadow: 0 0 0 0.2rem rgba(0,123,255,.25);
}
.full-width {
grid-column: span 2;
}
.calc-btn {
background-color: #007bff;
color: white;
border: none;
padding: 12px 20px;
font-size: 16px;
font-weight: 600;
border-radius: 4px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background-color 0.2s;
}
.calc-btn:hover {
background-color: #0056b3;
}
.results-box {
background-color: #fff;
border: 1px solid #dfe6ed;
border-radius: 6px;
padding: 20px;
margin-top: 25px;
display: none;
}
.results-box.visible {
display: block;
animation: fadeIn 0.5s;
}
.result-item {
display: flex;
justify-content: space-between;
align-items: center;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.result-item:last-child {
border-bottom: none;
}
.result-label {
font-weight: 500;
color: #555;
}
.result-value {
font-weight: 700;
color: #2c3e50;
font-size: 18px;
}
.highlight-result {
background-color: #e8f5e9;
padding: 15px;
border-radius: 5px;
margin-bottom: 15px;
border: 1px solid #c8e6c9;
}
.highlight-result .result-value {
color: #2e7d32;
font-size: 24px;
}
.seo-content h2 {
color: #2c3e50;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
margin-top: 40px;
}
.seo-content h3 {
color: #34495e;
margin-top: 25px;
}
.seo-content ul {
padding-left: 20px;
}
.seo-content li {
margin-bottom: 10px;
}
.error-msg {
color: #dc3545;
font-size: 14px;
margin-top: 5px;
display: none;
}
@keyframes fadeIn {
from { opacity: 0; transform: translateY(10px); }
to { opacity: 1; transform: translateY(0); }
}
@media (max-width: 600px) {
.input-grid {
grid-template-columns: 1fr;
}
.full-width {
grid-column: span 1;
}
}
function calculateConcrete() {
// Get Input Values
var length = parseFloat(document.getElementById('slabLength').value);
var width = parseFloat(document.getElementById('slabWidth').value);
var thicknessInches = parseFloat(document.getElementById('slabThickness').value);
var wastePercent = parseFloat(document.getElementById('wasteFactor').value);
var pricePerBag = parseFloat(document.getElementById('bagPrice').value);
// Error Handling
var errorDiv = document.getElementById('errorDisplay');
if (isNaN(length) || isNaN(width) || length <= 0 || width 0) {
totalCost = bags80 * pricePerBag;
showCost = true;
}
// Update DOM Results
document.getElementById('resYards').innerText = cubicYards.toFixed(2);
document.getElementById('resFeet').innerText = totalCubicFeet.toFixed(2);
document.getElementById('res80bags').innerText = bags80;
document.getElementById('res60bags').innerText = bags60;
if (showCost) {
document.getElementById('resCost').innerText = totalCost.toFixed(2);
document.getElementById('costRow').style.display = 'flex';
} else {
document.getElementById('costRow').style.display = 'none';
}
// Show Result Box
var resultBox = document.getElementById('results');
resultBox.classList.add('visible');
}
Concrete Slab Calculator
4 inches (Standard)
5 inches
6 inches (Heavy Load)
3 inches
8 inches
0% (Exact)
5% (Recommended)
10% (Complex Shapes)
Please enter valid dimensions.
Total Concrete Needed:
0 Cubic Yards
Volume in Cubic Feet:
0 cu. ft.
80lb Bags Required:
0
60lb Bags Required:
0
Estimated Material Cost (80lb bags):
$0.00
How to Calculate Concrete for Slabs
Planning a patio, driveway, or shed foundation requires accurate material estimation to avoid costly mid-project shortages or unnecessary waste. This Concrete Slab Calculator helps you determine the exact volume of concrete needed based on the standard industry formula.
The Concrete Calculation Formula
To calculate the concrete volume, we use the basic volume formula: Length × Width × Thickness.
- Convert Dimensions: Ensure all units are consistent. Since concrete is sold by the cubic yard, but thickness is measured in inches, we convert the thickness to feet first (Inches ÷ 12).
- Calculate Cubic Feet: Multiply Length (ft) × Width (ft) × Thickness (ft).
- Convert to Cubic Yards: Divide the total cubic feet by 27 (since there are 27 cubic feet in one cubic yard).
Pre-Mix Bags vs. Ready-Mix Truck
Should you buy bags or order a truck? Use these rules of thumb:
- Under 1 Cubic Yard: It is usually more economical to mix it yourself using 60lb or 80lb bags of pre-mix concrete.
- Over 1 Cubic Yard: Ordering "Ready-Mix" concrete from a truck is often cheaper and ensures a more consistent cure, though you may face delivery minimums.
Why Include a Waste Factor?
Professional contractors always include a safety margin (usually 5% to 10%) to account for:
- Spillage during mixing or pouring.
- Uneven subgrade (ground) depth.
- Settling of the formwork.
Our calculator defaults to a 5% waste factor to ensure you have enough material to finish the job without running back to the hardware store.
Standard Thickness Guide
- 4 Inches: Standard for walkways, patios, and residential shed floors.
- 5-6 Inches: Recommended for driveways and areas holding heavy vehicles.