Use this calculator to estimate the materials and associated costs for your retaining wall project. It provides calculations for both concrete block and poured concrete walls, along with the necessary gravel backfill.
(For poured concrete, this is the wall thickness. For block walls, use the block's depth in feet.)
Gravel Backfill Dimensions
(Width of the drainage layer behind the wall.)
(Height of the drainage layer, typically up to the wall height or slightly less.)
Material Specifics & Costs
Enter the dimensions and unit costs for the materials you are considering. The calculator will provide estimates for both block and poured concrete walls, allowing you to compare.
Concrete Block Details
Poured Concrete & Gravel Costs
Calculation Results
General Wall Metrics
Wall Surface Area (front face): 0 sq ft
For a Concrete Block Wall:
Estimated Number of Blocks: 0 (includes 10% waste)
function calculateRetainingWall() {
var wallHeightFt = parseFloat(document.getElementById('wallHeightFt').value);
var wallLengthFt = parseFloat(document.getElementById('wallLengthFt').value);
var wallDepthFt = parseFloat(document.getElementById('wallDepthFt').value); // Used for poured concrete volume
var gravelBackfillWidthFt = parseFloat(document.getElementById('gravelBackfillWidthFt').value);
var gravelBackfillHeightFt = parseFloat(document.getElementById('gravelBackfillHeightFt').value);
var blockLengthIn = parseFloat(document.getElementById('blockLengthIn').value);
var blockHeightIn = parseFloat(document.getElementById('blockHeightIn').value);
var blockDepthIn = parseFloat(document.getElementById('blockDepthIn').value); // Not directly used in block count, but good to have
var blockCost = parseFloat(document.getElementById('blockCost').value);
var concreteCostPerCubicYard = parseFloat(document.getElementById('concreteCostPerCubicYard').value);
var gravelCostPerCubicYard = parseFloat(document.getElementById('gravelCostPerCubicYard').value);
var errorMessages = [];
// Input validation
if (isNaN(wallHeightFt) || wallHeightFt <= 0) errorMessages.push("Please enter a valid Wall Height (must be a positive number).");
if (isNaN(wallLengthFt) || wallLengthFt <= 0) errorMessages.push("Please enter a valid Wall Length (must be a positive number).");
if (isNaN(wallDepthFt) || wallDepthFt <= 0) errorMessages.push("Please enter a valid Wall Depth/Thickness (must be a positive number).");
if (isNaN(gravelBackfillWidthFt) || gravelBackfillWidthFt < 0) errorMessages.push("Please enter a valid Gravel Backfill Width (cannot be negative).");
if (isNaN(gravelBackfillHeightFt) || gravelBackfillHeightFt < 0) errorMessages.push("Please enter a valid Gravel Backfill Height (cannot be negative).");
if (isNaN(blockLengthIn) || blockLengthIn <= 0) errorMessages.push("Please enter a valid Block Length (must be a positive number).");
if (isNaN(blockHeightIn) || blockHeightIn <= 0) errorMessages.push("Please enter a valid Block Height (must be a positive number).");
if (isNaN(blockDepthIn) || blockDepthIn <= 0) errorMessages.push("Please enter a valid Block Depth (must be a positive number).");
if (isNaN(blockCost) || blockCost < 0) errorMessages.push("Please enter a valid Block Cost (cannot be negative).");
if (isNaN(concreteCostPerCubicYard) || concreteCostPerCubicYard < 0) errorMessages.push("Please enter a valid Concrete Cost per Cubic Yard (cannot be negative).");
if (isNaN(gravelCostPerCubicYard) || gravelCostPerCubicYard 0) {
document.getElementById('errorMessages').innerHTML = errorMessages.join(");
document.getElementById('wallSurfaceAreaSqFt').textContent = '0';
document.getElementById('numBlocks').textContent = '0';
document.getElementById('estimatedBlockCost').textContent = '0.00';
document.getElementById('pouredConcreteVolumeCuYd').textContent = '0.00';
document.getElementById('estimatedPouredConcreteCost').textContent = '0.00';
document.getElementById('gravelVolumeCuYd').textContent = '0.00';
document.getElementById('estimatedGravelCost').textContent = '0.00';
return;
} else {
document.getElementById('errorMessages').innerHTML = ";
}
// Calculations
var wallSurfaceAreaSqFt = wallHeightFt * wallLengthFt;
// Poured Concrete Volume
var pouredConcreteVolumeCuFt = wallHeightFt * wallLengthFt * wallDepthFt;
var pouredConcreteVolumeCuYd = pouredConcreteVolumeCuFt / 27; // 1 cubic yard = 27 cubic feet
// Number of Blocks
var wallAreaSqIn = (wallHeightFt * 12) * (wallLengthFt * 12);
var blockAreaSqIn = blockLengthIn * blockHeightIn;
var numBlocks = (wallAreaSqIn / blockAreaSqIn) * 1.10; // Add 10% for waste, cuts, and breakage
numBlocks = Math.ceil(numBlocks); // Round up to the nearest whole block
// Gravel Volume
var gravelVolumeCuFt = gravelBackfillWidthFt * gravelBackfillHeightFt * wallLengthFt;
var gravelVolumeCuYd = gravelVolumeCuFt / 27;
// Costs
var estimatedBlockCost = numBlocks * blockCost;
var estimatedPouredConcreteCost = pouredConcreteVolumeCuYd * concreteCostPerCubicYard;
var estimatedGravelCost = gravelVolumeCuYd * gravelCostPerCubicYard;
// Display Results
document.getElementById('wallSurfaceAreaSqFt').textContent = wallSurfaceAreaSqFt.toFixed(2);
document.getElementById('numBlocks').textContent = numBlocks;
document.getElementById('estimatedBlockCost').textContent = estimatedBlockCost.toFixed(2);
document.getElementById('pouredConcreteVolumeCuYd').textContent = pouredConcreteVolumeCuYd.toFixed(2);
document.getElementById('estimatedPouredConcreteCost').textContent = estimatedPouredConcreteCost.toFixed(2);
document.getElementById('gravelVolumeCuYd').textContent = gravelVolumeCuYd.toFixed(2);
document.getElementById('estimatedGravelCost').textContent = estimatedGravelCost.toFixed(2);
}
// Run calculation on page load with default values
window.onload = calculateRetainingWall;
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font-size: 0.85em;
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Understanding Retaining Walls and Their Construction
A retaining wall is a structure designed to hold back soil and prevent erosion, creating level areas in sloped landscapes. They are essential for landscaping, creating usable yard space, preventing soil runoff, and supporting foundations on uneven terrain. Building a retaining wall requires careful planning, considering factors like soil type, drainage, wall height, and material choice.
Why Build a Retaining Wall?
Erosion Control: Prevents soil from washing away on slopes, protecting property and plants.
Creating Usable Space: Transforms sloped yards into flat, functional areas for gardens, patios, or play areas.
Aesthetic Appeal: Adds architectural interest and definition to a landscape.
Foundation Support: Can be used to support the base of a building on a hillside.
Key Considerations for Retaining Wall Projects
Before starting your project, it's crucial to understand several key aspects:
Height and Engineering: Walls over a certain height (often 3-4 feet, depending on local codes) typically require professional engineering design and permits. This is due to the significant lateral pressure exerted by the soil, which can cause walls to fail if not properly designed.
Drainage: Proper drainage is paramount. Without it, water can build up behind the wall, increasing hydrostatic pressure and leading to failure. This usually involves a layer of gravel backfill, a perforated drain pipe (weep holes), and sometimes geotextile fabric.
Material Choice: Common materials include:
Concrete Blocks: Interlocking or dry-stacked blocks are popular for DIY projects due to their ease of installation.
Poured Concrete: Offers superior strength and durability, often used for taller or more critical applications, but requires professional forming and pouring.
Timber/Railroad Ties: More rustic look, but can be prone to rot over time.
Natural Stone: Offers a beautiful, natural aesthetic but can be labor-intensive to install.
Foundation/Footing: A stable base is critical. This often involves a compacted gravel base or a concrete footing, especially for taller walls.
Soil Type: The type of soil behind the wall (e.g., clay, sand, loam) significantly impacts the lateral pressure and thus the wall's design requirements.
How to Use the Retaining Wall Calculator
Our Retaining Wall Material & Cost Estimator helps you get a preliminary idea of the materials needed and their potential costs. Here's how to use it:
Wall Dimensions: Enter the planned height and length of your retaining wall in feet. The "Wall Depth/Thickness" should reflect the depth of your chosen material (e.g., the depth of a concrete block, or the thickness of a poured concrete wall).
Gravel Backfill: Input the desired width and height of your gravel drainage layer behind the wall. This is crucial for preventing water buildup.
Material Specifics & Costs:
Concrete Block: Provide the standard length, height, and depth of the blocks you plan to use (in inches), along with their individual cost.
Poured Concrete & Gravel: Enter the estimated cost per cubic yard for poured concrete and for the gravel backfill.
Calculate: Click the "Calculate Materials & Costs" button.
Understanding Your Results
The calculator will provide:
Wall Surface Area: Useful for estimating facing materials or sealants.
Estimated Number of Blocks: Includes a 10% waste factor for cuts and breakage.
Estimated Poured Concrete Volume: In cubic yards, based on your wall's dimensions.
Estimated Gravel Volume: In cubic yards, for your drainage layer.
Estimated Material Costs: Separate costs for blocks, poured concrete, and gravel, allowing you to compare options.
Disclaimer: This calculator provides estimates for material quantities and costs only. It does not account for labor, equipment rental, delivery fees, or complex engineering requirements. Always consult with a qualified engineer or contractor for detailed design, structural integrity, and accurate cost estimates for your specific retaining wall project, especially for walls over 3-4 feet in height or in areas with poor soil conditions.