Typical values range from 90-120 lbs/cu ft. Consult your supplier for specifics.
Enter the dimensions and price to see your estimated rock needs and cost.
Understanding Your Driveway Rock Needs
Adding a layer of gravel or crushed stone to your driveway is a practical and cost-effective way to improve its appearance, durability, and stability. Whether you're building a new driveway or refreshing an old one, knowing how much material to order is crucial to avoid under or over-ordering. This calculator helps you estimate the volume and approximate cost of rock needed for your project.
How the Calculation Works
The calculation involves several steps:
Convert Units: The desired depth is usually given in inches, but for volume calculations (cubic feet), we need to convert it to feet. This is done by dividing the inches by 12.
Formula: Depth (ft) = Depth (inches) / 12
Calculate Volume: Once all dimensions are in feet, we can calculate the total volume of rock needed in cubic feet.
Convert Volume to Tons: Rock is typically sold by the ton. To convert the volume from cubic feet to tons, we use the density of the rock (weight per cubic foot). First, we find the weight in pounds.
Formula: Weight (lbs) = Volume (cu ft) * Density (lbs/cu ft)
Since there are 2,000 pounds in a ton:
Formula: Weight (tons) = Weight (lbs) / 2000
Calculate Total Cost: With the total weight in tons and the price per ton, we can determine the estimated cost.
Formula: Total Cost = Weight (tons) * Price per Ton ($/ton)
Example Calculation
Let's consider a driveway that is 50 feet long, 10 feet wide, and you desire a 4-inch depth of gravel. The gravel has a density of 100 lbs per cubic foot, and it costs $35 per ton.
Convert Depth: 4 inches / 12 = 0.333 feet
Calculate Volume: 50 ft * 10 ft * 0.333 ft = 166.5 cubic feet
Convert to Tons:
Weight (lbs): 166.5 cu ft * 100 lbs/cu ft = 16,650 lbs
In this example, you would need approximately 8.33 tons of rock, costing around $291.38.
Factors to Consider
Layering: For new driveways or those requiring significant stabilization, you might need multiple layers (e.g., a base layer of larger aggregate and a top layer of finer gravel). This calculator is for a single, uniform layer.
Compaction: Some materials compact more than others. You might need slightly more material to account for compaction.
Waste and Spillage: Always order a little extra (5-10%) to account for uneven distribution, spillage, and potential settling.
Rock Type: Different types of gravel and crushed stone have slightly different densities and sizes, affecting coverage and compaction. Consult your supplier for recommendations.
Existing Base: If you have a well-compacted existing base, you might be able to get away with a shallower depth than for a completely new sub-base.
Using this calculator provides a solid estimate to help you plan your budget and order materials efficiently for your driveway project.
function calculateRock() {
var length = parseFloat(document.getElementById("drivewayLength").value);
var width = parseFloat(document.getElementById("drivewayWidth").value);
var depthInches = parseFloat(document.getElementById("desiredDepth").value);
var density = parseFloat(document.getElementById("rockDensity").value);
var pricePerTon = parseFloat(document.getElementById("rockPricePerTon").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = "; // Clear previous results
if (isNaN(length) || isNaN(width) || isNaN(depthInches) || isNaN(density) || isNaN(pricePerTon)) {
resultDiv.innerHTML = 'Please enter valid numbers for all fields.';
return;
}
if (length <= 0 || width <= 0 || depthInches <= 0 || density <= 0 || pricePerTon < 0) {
resultDiv.innerHTML = 'Dimensions and density must be positive. Price cannot be negative.';
return;
}
// Calculations
var depthFeet = depthInches / 12;
var volumeCubicFeet = length * width * depthFeet;
var weightPounds = volumeCubicFeet * density;
var weightTons = weightPounds / 2000;
var totalCost = weightTons * pricePerTon;
// Rounding for display
var roundedTons = weightTons.toFixed(2);
var roundedCost = totalCost.toFixed(2);
resultDiv.innerHTML = 'Estimated Rock Needed: ' + roundedTons + ' tons' +
'Estimated Cost: $' + roundedCost + '';
}