.calc-header { text-align: center; margin-bottom: 30px; }
.calc-header h2 { color: #2c3e50; font-size: 28px; margin-bottom: 10px; }
.calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
@media (max-width: 600px) { .calc-grid { grid-template-columns: 1fr; } }
.form-group { margin-bottom: 15px; }
.form-group label { display: block; margin-bottom: 5px; font-weight: 600; color: #34495e; font-size: 14px; }
.form-group input { width: 100%; padding: 10px; border: 1px solid #ddd; border-radius: 4px; font-size: 16px; box-sizing: border-box; }
.form-group input:focus { border-color: #3498db; outline: none; box-shadow: 0 0 0 2px rgba(52,152,219,0.2); }
.form-section-title { grid-column: 1 / -1; margin-top: 10px; margin-bottom: 10px; border-bottom: 2px solid #eee; padding-bottom: 5px; color: #7f8c8d; font-size: 14px; text-transform: uppercase; letter-spacing: 1px; }
.calc-btn { grid-column: 1 / -1; background-color: #e67e22; color: white; border: none; padding: 15px; font-size: 18px; font-weight: bold; border-radius: 4px; cursor: pointer; transition: background 0.3s; margin-top: 10px; width: 100%; }
.calc-btn:hover { background-color: #d35400; }
.results-box { grid-column: 1 / -1; background-color: #f8f9fa; padding: 20px; border-radius: 6px; border-left: 5px solid #27ae60; margin-top: 20px; display: none; }
.results-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 15px; }
.result-item { background: white; padding: 15px; border-radius: 4px; box-shadow: 0 2px 5px rgba(0,0,0,0.05); text-align: center; }
.result-label { font-size: 13px; color: #7f8c8d; display: block; margin-bottom: 5px; }
.result-value { font-size: 20px; font-weight: bold; color: #2c3e50; }
.result-value.highlight { color: #27ae60; }
.seo-content { margin-top: 40px; border-top: 1px solid #eee; padding-top: 20px; line-height: 1.6; color: #444; }
.seo-content h2 { font-size: 24px; color: #2c3e50; margin-top: 30px; }
.seo-content h3 { font-size: 18px; color: #34495e; margin-top: 20px; }
.seo-content p { margin-bottom: 15px; }
.seo-content ul { margin-bottom: 15px; padding-left: 20px; }
.seo-content li { margin-bottom: 8px; }
.error-msg { color: #c0392b; font-size: 14px; display: none; margin-top: 5px; }
function calculateConcrete() {
var len = parseFloat(document.getElementById('slabLength').value);
var wid = parseFloat(document.getElementById('slabWidth').value);
var thick = parseFloat(document.getElementById('slabThickness').value);
var waste = parseFloat(document.getElementById('wasteFactor').value);
var price = parseFloat(document.getElementById('pricePerYard').value);
// Validation
if (isNaN(len) || isNaN(wid) || isNaN(thick) || len <= 0 || wid <= 0 || thick <= 0) {
document.getElementById('errorDisplay').style.display = 'block';
document.getElementById('resultsArea').style.display = 'none';
return;
} else {
document.getElementById('errorDisplay').style.display = 'none';
}
// Default defaults
if (isNaN(waste)) waste = 0;
if (isNaN(price)) price = 0;
// Math Logic
// 1. Calculate raw volume in cubic feet: L * W * (Thick/12)
var rawCuFt = len * wid * (thick / 12);
// 2. Add waste percentage
var totalCuFt = rawCuFt * (1 + (waste / 100));
// 3. Convert to Cubic Yards (1 Yard = 27 Cubic Feet)
var totalCuYards = totalCuFt / 27;
// 4. Calculate Bags
// Typical yields: 80lb bag ~= 0.60 cu ft, 60lb bag ~= 0.45 cu ft
var bags80 = Math.ceil(totalCuFt / 0.60);
var bags60 = Math.ceil(totalCuFt / 0.45);
// 5. Calculate Cost (based on bulk yards)
var totalCost = totalCuYards * price;
// Display Results
document.getElementById('resYards').innerHTML = totalCuYards.toFixed(2) + "
";
document.getElementById('resFeet').innerHTML = totalCuFt.toFixed(2) + "
";
document.getElementById('resBags60').innerText = bags60;
document.getElementById('resBags80').innerText = bags80;
if (price > 0) {
document.getElementById('resCost').innerText = "$" + totalCost.toFixed(2);
} else {
document.getElementById('resCost').innerText = "N/A";
}
document.getElementById('resultsArea').style.display = 'block';
}
How to Calculate Concrete for Slabs, Patios, and Driveways
Whether you are pouring a backyard patio, a driveway, or a foundation slab, determining the exact amount of concrete required is the first critical step to a successful project. Ordering too little concrete can lead to cold joints and structural weaknesses, while ordering too much is a waste of money. Our Concrete Slab Calculator helps homeowners and contractors estimate volume in cubic yards and cubic feet precisely.
The Concrete Calculation Formula
To calculate the concrete volume manually, you need to determine the area of the slab and multiply it by the depth. Since concrete is sold by the Cubic Yard (yd³) but dimensions are often measured in feet and inches, unit conversion is necessary.
The basic formula is:
- Step 1: Convert thickness from inches to feet (divide inches by 12).
- Step 2: Multiply Length (ft) × Width (ft) × Thickness (ft) = Cubic Feet (ft³).
- Step 3: Divide Cubic Feet by 27 to get Cubic Yards (yd³).
Why Include a Waste Factor?
In the construction industry, it is standard practice to include a "waste" or "spillage" margin. This accounts for several factors:
- Uneven subgrade or ground settlement.
- Spillage during transport from the truck or wheelbarrow.
- Slight variations in formwork dimensions.
We generally recommend adding 5% to 10% extra material for standard projects to ensure you don't run short during the pour.
Premix Bags vs. Ready-Mix Truck
For smaller projects (typically under 1 to 1.5 cubic yards), buying premixed bags (60lb or 80lb) from a hardware store is often more economical. For larger projects (driveways, large patios), ordering "Ready-Mix" concrete delivered by a truck is usually cheaper and labor-efficient.
Rule of Thumb: One cubic yard of concrete weighs approximately 4,000 lbs. That is equivalent to roughly forty-five 80lb bags. Mixing that amount by hand is labor-intensive!