Blacktop Calculator Square Feet: How to Measure

This calculator works out the square footage of a blacktop (asphalt) area. You enter the length and width of the surface in feet, and it returns the total area in square feet. It also provides the area in square yards, which is the unit most paving contractors use when quoting a job.

Formula

The formula for a rectangular blacktop area is:

Area (sq ft) = Length (ft) × Width (ft)

To convert to square yards, divide by 9, because 1 square yard = 9 square feet.

• Length – the longer side of the rectangle, measured in feet.
• Width – the shorter side of the rectangle, measured in feet.
• Area – the total surface covered, in square feet or square yards.

Worked Example

Using the default values from the calculator above:

1. Length = 40 ft, Width = 20 ft
2. Area = 40 × 20 = 800 sq ft
3. Convert to square yards: 800 ÷ 9 = 88.89 sq yd

The calculator shows 800 square feet and 88.89 square yards. That matches the formula exactly.

Why Square Footage Matters for Blacktop

Knowing the square footage is the first step in estimating how much asphalt you need. Asphalt is typically sold by the ton, and the tonnage depends on the area and the thickness of the pavement. A standard driveway is about 2–3 inches thick after compaction. For a rough estimate, 1 ton of asphalt covers about 80 square feet at 2 inches thick, or about 53 square feet at 3 inches thick. These numbers vary with the mix density, but they give you a ballpark.

Square yards matter because most paving contractors quote prices per square yard. If you know the area in square feet, divide by 9 to get square yards. For example, a 40 × 20 ft driveway is 88.89 sq yd, and at a typical price of $4–$6 per square yard for materials and labor, the cost would be roughly $356–$533. Prices vary widely by region and material, so always get local quotes.

How to Measure a Blacktop Area

Most blacktop surfaces are rectangles or can be split into rectangles. Here is the process:

1. Measure the length of the area in feet using a tape measure or a measuring wheel.
2. Measure the width in feet.
3. Multiply the two numbers to get square feet.
4. If the area is L-shaped or irregular, divide it into rectangles, measure each, and add the areas together.

For a circular area (like a turnaround), the formula is π × radius². For a triangular area, it’s (base × height) / 2. Most driveways, parking pads, and walkways are rectangles, so the simple formula works for the majority of projects.

Common Mistakes and How to Avoid Them

• Mixing units – Always measure in feet. If you measure in inches, convert to feet by dividing by 12 before multiplying.
• Forgetting the thickness – The square footage alone does not tell you how much asphalt you need. You must also decide the thickness. A thicker pavement requires more material.
• Ignoring waste – Add 5–10% extra for cuts, irregularities, and spillage. For a 800 sq ft driveway, add 40–80 sq ft.
• Confusing square feet with cubic feet – If you need to order asphalt by the cubic yard, multiply the area by the thickness (in feet) to get cubic feet, then divide by 27 to get cubic yards.

Square Feet vs. Square Yards vs. Tons

Here is a quick comparison of the units you will encounter:

• Square feet – the basic unit of area. Useful for measuring the surface itself.
• Square yards – 9 square feet per square yard. Commonly used in contractor quotes.
• Tons – a unit of weight. Asphalt density is typically about 145 pounds per cubic foot. To find tons, multiply cubic feet by 145 and divide by 2000.

For example, an 800 sq ft driveway at 3 inches thick (0.25 ft) is 200 cubic feet. That is 200 × 145 / 2000 = 14.5 tons of asphalt. This is a rough estimate; the actual density can vary.

When to Use This Calculator

Use this calculator when you need to:

• Estimate the amount of asphalt needed for a new driveway or parking area.
• Compare quotes from contractors by converting everything to square yards.
• Plan a resurfacing project where you only need the surface area.
• Calculate the cost of sealcoating, which is priced per square foot.

For a simple rectangular area, the math is straightforward. For complex shapes, break them into smaller rectangles and add the results. The calculator works for any rectangular area, whether it’s a driveway, a parking lot, or a basketball court.

Frequently Asked Questions

How many square feet does a ton of blacktop cover?

At 2 inches thick, one ton of asphalt covers roughly 80 square feet. At 3 inches thick, it covers about 53 square feet. These figures assume a density of about 145 pounds per cubic foot. The exact coverage depends on the mix and compaction, so use these as estimates only.

How do I calculate square yards from square feet?

Divide the square footage by 9. For example, 800 square feet divided by 9 equals 88.89 square yards. This is the unit most paving contractors use in their quotes.

What if my driveway is not a perfect rectangle?

Break the area into smaller rectangles, measure each, and add the square footages together. For a triangular section, use (base × height) / 2. For a circular section, use π × radius². Add all sections to get the total area.

How thick should a blacktop driveway be?

For residential driveways, a compacted thickness of 2–3 inches is common. Heavier vehicles or poor soil may require 4 inches or more. The thickness affects the amount of material you need, so decide before ordering.

Can I use this calculator for concrete too?

Yes, the area calculation is the same for any flat surface. However, concrete is usually ordered by the cubic yard, so you would need to multiply the area by the thickness (in feet) and divide by 27 to get cubic yards. The square footage is the same regardless of material.

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in length | Length | ft | 40 | 0
in width | Width | ft | 20 | 0
out sqft | Square Feet | sq ft | length * width | 0
out sqyd | Square Yards | sq yd | (length * width) / 9 | 2