.cc-calculator-widget {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 25px;
max-width: 600px;
margin: 20px auto;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.cc-calculator-title {
text-align: center;
font-size: 24px;
color: #333;
margin-bottom: 20px;
font-weight: 700;
}
.cc-input-group {
margin-bottom: 15px;
}
.cc-input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #555;
}
.cc-input-group input, .cc-input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.cc-row {
display: flex;
gap: 15px;
}
.cc-col {
flex: 1;
}
.cc-btn {
width: 100%;
background-color: #2c3e50;
color: white;
border: none;
padding: 15px;
font-size: 18px;
border-radius: 4px;
cursor: pointer;
transition: background 0.3s;
margin-top: 10px;
}
.cc-btn:hover {
background-color: #34495e;
}
.cc-results {
margin-top: 25px;
padding: 20px;
background: #fff;
border-left: 5px solid #27ae60;
display: none;
border-radius: 4px;
box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}
.cc-result-item {
margin-bottom: 15px;
padding-bottom: 15px;
border-bottom: 1px solid #eee;
}
.cc-result-item:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.cc-result-label {
font-size: 14px;
color: #777;
text-transform: uppercase;
letter-spacing: 0.5px;
}
.cc-result-value {
font-size: 28px;
font-weight: 700;
color: #27ae60;
}
.cc-sub-value {
font-size: 14px;
color: #666;
}
.cc-article {
max-width: 800px;
margin: 40px auto;
padding: 20px;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
}
.cc-article h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #ecf0f1;
padding-bottom: 10px;
}
.cc-article p {
margin-bottom: 15px;
}
.cc-article ul {
margin-bottom: 15px;
padding-left: 20px;
}
.cc-article li {
margin-bottom: 8px;
}
@media (max-width: 500px) {
.cc-row {
flex-direction: column;
gap: 0;
}
}
function calculateConcrete() {
var length = parseFloat(document.getElementById('cc_length').value);
var width = parseFloat(document.getElementById('cc_width').value);
var thickness = parseFloat(document.getElementById('cc_thickness').value);
var wastePercent = parseFloat(document.getElementById('cc_waste').value);
if (isNaN(length) || isNaN(width) || isNaN(thickness) || length <= 0 || width <= 0 || thickness <= 0) {
alert("Please enter valid positive numbers for Length, Width, and Thickness.");
return;
}
// 1. Calculate Cubic Feet: L * W * (Thickness in Feet)
var thicknessInFeet = thickness / 12;
var cubicFeet = length * width * thicknessInFeet;
// 2. Add Waste Margin
var totalCubicFeet = cubicFeet * (1 + (wastePercent / 100));
// 3. Convert to Cubic Yards (1 Yard = 27 Cubic Feet)
var cubicYards = totalCubicFeet / 27;
// 4. Calculate Bags
// 80lb bag yields approx 0.60 cubic feet
// 60lb bag yields approx 0.45 cubic feet
var bags80 = Math.ceil(totalCubicFeet / 0.60);
var bags60 = Math.ceil(totalCubicFeet / 0.45);
// Update UI
document.getElementById('res_yards').innerHTML = cubicYards.toFixed(2) + " Cubic Yards";
document.getElementById('res_feet').innerHTML = "(" + totalCubicFeet.toFixed(2) + " Cubic Feet)";
document.getElementById('res_bags80').innerHTML = bags80 + " Bags";
document.getElementById('res_bags60').innerHTML = bags60 + " Bags";
document.getElementById('cc_results').style.display = 'block';
}
How to Calculate Concrete for Your Slab
Whether you are pouring a patio, a driveway, or a foundation for a shed, calculating the correct amount of concrete is the most critical step in the planning process. Ordering too little results in expensive second deliveries and cold joints that weaken the slab, while ordering too much is a waste of money.
Our Concrete Slab Calculator helps you determine exactly how much volume you need in both cubic yards (for truck orders) and pre-mix bags (for smaller DIY projects).
The Concrete Calculation Formula
To calculate the concrete volume manually, you must determine the volume of the space in cubic feet and then convert it to cubic yards.
- Step 1: Measure the Length and Width of your slab in feet.
- Step 2: Measure the Thickness of the slab in inches and convert it to feet by dividing by 12.
- Step 3: Multiply Length × Width × Thickness (in feet) to get Cubic Feet.
- Step 4: Divide Cubic Feet by 27 to get Cubic Yards.
Formula: (Length × Width × (Thickness / 12)) / 27 = Cubic Yards
Why Include a Safety Margin?
It is standard industry practice to include a safety margin, often referred to as "waste," of 5% to 10%. This accounts for several variables encountered during the pour:
- Uneven Subgrade: The ground beneath your slab is rarely perfectly flat; dips require more concrete.
- Spillage: Minor amounts of concrete are often lost during wheelbarrow transport or screeding.
- Form Deflection: Wooden forms may bow slightly outward under the weight of wet concrete, increasing the volume.
Pre-Mix Bags vs. Ready-Mix Trucks
Should you buy bags or order a truck? This calculator provides estimates for both.
- Small Projects (Under 1 Yard): For sidewalks, fence posts, or small pads, buying 60lb or 80lb bags of pre-mix (like Quikrete or Sakrete) is usually more improved. Note that an 80lb bag yields approximately 0.60 cubic feet of cured concrete.
- Large Projects (Over 1 Yard): If your calculator result exceeds 1 cubic yard, it is generally more labor and cost-effective to order ready-mix concrete delivered by a truck. Mixing dozens of bags by hand ensures a difficult day and inconsistent curing times.
Standard Slab Thicknesses
Not sure how thick your concrete needs to be? Here are general guidelines:
- 4 Inches: Standard for walkways, patios, and shed floors.
- 5-6 Inches: Recommended for driveways and areas accommodating light passenger vehicles.
- 6+ Inches: Required for heavy equipment or commercial aprons.