#concrete-calculator-wrapper .calc-box {
background: #f9f9f9;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0,0,0,0.1);
margin-bottom: 40px;
}
#concrete-calculator-wrapper h2 {
color: #2c3e50;
border-bottom: 2px solid #3498db;
padding-bottom: 10px;
margin-top: 30px;
}
#concrete-calculator-wrapper .form-group {
margin-bottom: 20px;
}
#concrete-calculator-wrapper label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #444;
}
#concrete-calculator-wrapper input[type="number"] {
width: 100%;
padding: 12px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
#concrete-calculator-wrapper .btn-calc {
background-color: #3498db;
color: white;
border: none;
padding: 15px 30px;
font-size: 18px;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background-color 0.3s;
font-weight: bold;
}
#concrete-calculator-wrapper .btn-calc:hover {
background-color: #2980b9;
}
#concrete-calculator-wrapper #calc-results {
display: none;
background-color: #e8f6ff;
border: 1px solid #b3e0ff;
padding: 20px;
border-radius: 4px;
margin-top: 25px;
}
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display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #d0e9fc;
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#concrete-calculator-wrapper .result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
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#concrete-calculator-wrapper .result-label {
font-weight: 600;
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#concrete-calculator-wrapper .result-value {
font-weight: bold;
color: #2c3e50;
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#concrete-calculator-wrapper .article-content {
line-height: 1.6;
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#concrete-calculator-wrapper ul {
background: #fff;
border: 1px solid #eee;
padding: 20px 40px;
border-radius: 4px;
}
function calculateConcrete() {
// Get input values
var length = parseFloat(document.getElementById('slabLength').value);
var width = parseFloat(document.getElementById('slabWidth').value);
var thickInches = parseFloat(document.getElementById('slabThickness').value);
var wastePercent = parseFloat(document.getElementById('wasteFactor').value);
// Validation
if (isNaN(length) || isNaN(width) || isNaN(thickInches)) {
alert("Please enter valid numbers for Length, Width, and Thickness.");
return;
}
if (length <= 0 || width <= 0 || thickInches <= 0) {
alert("Dimensions must be greater than zero.");
return;
}
if (isNaN(wastePercent)) {
wastePercent = 0;
}
// Calculation Logic
// 1. Convert thickness to feet
var thickFeet = thickInches / 12;
// 2. Calculate Cubic Feet
var cubicFeet = length * width * thickFeet;
// 3. Add Waste
var wasteMultiplier = 1 + (wastePercent / 100);
var totalCubicFeet = cubicFeet * wasteMultiplier;
// 4. Convert to Cubic Yards
var cubicYards = totalCubicFeet / 27;
// 5. Calculate Bags
// Standard yield: 80lb bag = 0.60 cu ft, 60lb bag = 0.45 cu ft
var bags80 = totalCubicFeet / 0.60;
var bags60 = totalCubicFeet / 0.45;
// Display Results
document.getElementById('calc-results').style.display = 'block';
// Format numbers: Yards to 2 decimals, Bags rounded up to nearest whole number
document.getElementById('resYards').innerHTML = cubicYards.toFixed(2) + " cu. yd.";
document.getElementById('resFeet').innerHTML = totalCubicFeet.toFixed(2) + " cu. ft.";
document.getElementById('res80lb').innerHTML = Math.ceil(bags80) + " bags";
document.getElementById('res60lb').innerHTML = Math.ceil(bags60) + " bags";
}
Concrete Slab Calculator
Material Estimates
Total Volume (Cubic Yards):
–
Total Volume (Cubic Feet):
–
80lb Bags (Pre-mix):
–
60lb Bags (Pre-mix):
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How to Calculate Concrete for a Slab
Whether you are pouring a patio, a driveway, or a foundation for a shed, calculating the correct amount of concrete is critical. Ordering too little can result in a structural weakness known as a "cold joint," while ordering too much is a waste of money.
The standard unit of measure for concrete volume is the cubic yard. However, for smaller DIY projects using pre-mixed bags (like Quikrete or Sakrete), you will need to know the number of bags required based on the volume in cubic feet.
The Concrete Formula
To determine the volume of your slab, use the following steps:
- Step 1: Convert the thickness of the slab from inches to feet. Do this by dividing the inches by 12.
Example: 4 inches / 12 = 0.333 feet. - Step 2: Multiply the Length (ft) x Width (ft) x Thickness (ft) to get Cubic Feet.
- Step 3: To convert Cubic Feet to Cubic Yards, divide the total by 27 (since there are 27 cubic feet in one cubic yard).
Understanding Waste Factors
It is standard industry practice to include a "waste factor" or margin of safety in your calculation. Ground surfaces are rarely perfectly level, and spillage occurs during the pour. We recommend adding:
- 5% Waste: For simple, square forms on level ground.
- 10% Waste: For irregular shapes or uneven subgrades.
Bag Yield Reference
If you are mixing concrete by hand using pre-mixed bags, here are the standard yield conversions used in this calculator:
- 80lb Bag: Yields approximately 0.60 cubic feet.
- 60lb Bag: Yields approximately 0.45 cubic feet.