.cc-row { display: flex; flex-wrap: wrap; margin: 0 -10px; }
.cc-col { flex: 1; min-width: 200px; padding: 0 10px; margin-bottom: 15px; }
.cc-label { display: block; font-weight: 600; margin-bottom: 5px; color: #333; }
.cc-input { width: 100%; padding: 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; box-sizing: border-box; transition: border 0.3s; }
.cc-input:focus { border-color: #f7a800; outline: none; }
.cc-btn { width: 100%; padding: 12px; background-color: #f7a800; color: #fff; border: none; border-radius: 4px; font-size: 18px; font-weight: bold; cursor: pointer; transition: background 0.3s; margin-top: 10px; }
.cc-btn:hover { background-color: #e09600; }
.cc-results { margin-top: 25px; background: #f9f9f9; padding: 20px; border-radius: 4px; border-left: 5px solid #f7a800; display: none; }
.cc-result-item { margin-bottom: 10px; font-size: 16px; border-bottom: 1px dashed #ddd; padding-bottom: 5px; display: flex; justify-content: space-between; }
.cc-result-val { font-weight: 700; color: #222; }
.cc-disclaimer { font-size: 12px; color: #777; margin-top: 10px; font-style: italic; }
h2.cc-heading { color: #333; border-bottom: 2px solid #f7a800; padding-bottom: 10px; margin-top: 30px; }
.cc-article p { line-height: 1.6; color: #444; margin-bottom: 15px; }
.cc-article ul { margin-bottom: 15px; line-height: 1.6; color: #444; }
function calculateConcrete() {
// 1. Get input values
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 waste = parseFloat(document.getElementById('cc_waste').value);
// 2. Validate inputs
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;
}
if (isNaN(waste) || waste < 0) {
waste = 0;
}
// 3. Perform Calculations
// Convert thickness from inches to feet
var thicknessFeet = thickness / 12;
// Calculate Cubic Feet
var cubicFeet = length * width * thicknessFeet;
// Calculate Cubic Yards (1 Yard = 27 Cubic Feet)
var cubicYards = cubicFeet / 27;
// Apply Waste Margin
var wasteMultiplier = 1 + (waste / 100);
var totalCubicFeet = cubicFeet * wasteMultiplier;
var totalCubicYards = cubicYards * wasteMultiplier;
// Calculate Bags
// Standard concrete weight is roughly 145 lbs/ft^3 for cured,
// but approx 133 lbs/ft^3 (approx 0.6 ft3 per 80lb bag) for dry mix estimation.
// 80lb bag yields approx 0.6 cubic feet.
// 60lb bag yields approx 0.45 cubic feet.
// Using yield formula: Volume Needed / Yield per bag
var bags80 = Math.ceil(totalCubicFeet / 0.6);
var bags60 = Math.ceil(totalCubicFeet / 0.45);
// 4. Update Result Display
document.getElementById('res_yards').innerText = totalCubicYards.toFixed(2);
document.getElementById('res_feet').innerText = totalCubicFeet.toFixed(2);
document.getElementById('res_bags80').innerText = bags80;
document.getElementById('res_bags60').innerText = bags60;
// Show the result container
document.getElementById('cc_result_area').style.display = 'block';
}
How to Calculate Concrete for Slabs and Footings
Whether you are pouring a patio, a driveway, or footings for a deck, calculating the correct amount of concrete is crucial for budget control and structural integrity. Ordering too little results in "cold joints" which weaken the structure, while ordering too much wastes money and creates disposal issues.
The Concrete Formula
Concrete is measured by volume, typically in Cubic Yards for ready-mix truck deliveries, or by the bag (cubic feet) for smaller DIY projects. The formula to determine the volume is:
Length (ft) × Width (ft) × Thickness (ft) = Cubic Feet
To convert Cubic Feet to Cubic Yards, divide the total by 27.
Standard Thickness Guide
The thickness of your slab depends heavily on its intended use:
- 4 Inches: Standard for residential sidewalks, patios, and garage floors used for passenger cars.
- 5-6 Inches: Recommended for driveways that accommodate heavier vehicles (trucks/SUVs) or areas with poor soil conditions.
- 8+ Inches: Heavy-duty industrial floors or commercial driveways.
Understanding Pre-Mix Concrete Bags
For smaller projects (typically under 1 cubic yard), using pre-mixed bags from a hardware store is often more economical than paying the delivery fee for a truck. Here is the general yield for standard bags:
- 80lb Bag: Yields approximately 0.60 cubic feet of concrete.
- 60lb Bag: Yields approximately 0.45 cubic feet of concrete.
Pro Tip: Always add a "Waste Margin" of 5-10% to account for spillage, uneven subgrade depths, and material that stays in the mixer. Our calculator defaults to a 5% safety margin.
Preparation Checklist
Before you pour, ensure you have properly prepared the site:
- Compact the Subgrade: Ensure the soil beneath is firm and level.
- Add a Gravel Base: A 4-inch layer of compactable gravel improves drainage and stability.
- Reinforcement: Use rebar or wire mesh to increase the tensile strength of the slab and reduce cracking.