function calculateAsphalt() {
// 1. Get input values
var length = document.getElementById("lengthFt").value;
var width = document.getElementById("widthFt").value;
var thickness = document.getElementById("thicknessIn").value;
var density = document.getElementById("density").value;
var price = document.getElementById("pricePerTon").value;
// 2. Validate inputs
if (length === "" || width === "" || thickness === "" || density === "") {
alert("Please fill in Length, Width, Thickness, and Density.");
return;
}
// 3. Parse numbers
var lenVal = parseFloat(length);
var widVal = parseFloat(width);
var thickVal = parseFloat(thickness);
var densVal = parseFloat(density);
var priceVal = parseFloat(price);
if (isNaN(priceVal)) {
priceVal = 0;
}
// 4. Calculations
// Area in square feet
var areaSqFt = lenVal * widVal;
// Thickness converted to feet (inches / 12)
var thickFt = thickVal / 12;
// Volume in Cubic Feet
var volCuFt = areaSqFt * thickFt;
// Volume in Cubic Yards (27 cubic feet in 1 cubic yard)
var volCuYds = volCuFt / 27;
// Total Weight in Pounds (Volume ft³ * Density lbs/ft³)
var weightLbs = volCuFt * densVal;
// Total Weight in Tons (2000 lbs in 1 ton)
var totalTons = weightLbs / 2000;
// Total Cost
var totalCost = totalTons * priceVal;
// 5. Update UI
document.getElementById("resArea").innerText = areaSqFt.toFixed(2) + " sq ft";
document.getElementById("resVolume").innerText = volCuYds.toFixed(2) + " cu yds";
document.getElementById("resTons").innerText = totalTons.toFixed(2) + " Tons";
if (priceVal > 0) {
document.getElementById("resCost").innerText = "$" + totalCost.toFixed(2);
} else {
document.getElementById("resCost").innerText = "N/A";
}
// Show result box
document.getElementById("resultBox").style.display = "block";
}
How Do You Calculate Asphalt Tonnage?
Calculating the correct amount of asphalt for a paving project is critical for budgeting and ensuring structural integrity. Whether you are paving a residential driveway, a parking lot, or a highway, ordering too little material causes work stoppages, while ordering too much leads to expensive waste.
The calculation requires three primary dimensions: length, width, and thickness. Additionally, you must account for the density of the asphalt mixture being used. The standard formula used by contractors and engineers is relatively straightforward once you convert your measurements into the correct units.
The Asphalt Tonnage Formula
To determine how many tons of asphalt you need, you first calculate the volume of the area in cubic feet and then multiply it by the density of the asphalt. Finally, divide by 2,000 to convert pounds into tons.
Convert to Tons: 36,250 lbs ÷ 2,000 = 18.125 Tons.
Why is Asphalt Density Important?
Density refers to how much a cubic foot of the compacted asphalt weighs. While 145 lbs/ft³ is the standard default used for general estimates, different aggregate mixes can vary slightly. Fine mixes might be lighter, while coarser mixes with heavy stone might be denser. If you are working with a specific supplier, ask for their mix density to get the most precise calculation.
Factoring in Waste
No project goes perfectly. It is standard practice to order slightly more asphalt than the exact math suggests to account for:
Irregularities in the subgrade (ground unevenness).
Material stuck in the truck bed or paver.
Spillage during transfer.
Most contractors recommend adding a 5% to 10% safety margin to your total tonnage. For the example above (18.125 tons), adding 5% would mean ordering approximately 19 tons.
Cost Estimation
Once you have the total tonnage, estimating the material cost is simple multiplication. If local asphalt prices are $100 per ton, a 19-ton load would cost $1,900 for the material alone. Keep in mind that this does not include labor, trucking fees, or equipment rental.