Feet, Inches, Square Yards, Square Feet, Oh My!

Paving bids use several units of measure, mainly square feet, square yards, inches, and tons, and each one describes something different. One square yard equals 9 square feet, so a price per square yard cannot be compared directly with a price per square foot. Before comparing bids, confirm the unit on every line, and see how driveway paving estimates are typically laid out.

Why do bids use both square feet and square yards?

Square feet measure area, which is length times width, in the units most people know from a tape measure. Square yards measure the same area in larger units, and contractors often use them because they match how paving materials are commonly figured. To convert square feet to square yards, divide by 9. For example, an area of 900 square feet is 100 square yards. To go the other way, multiply square yards by 9.

How do inches of thickness change the amount of material?

Thickness is the depth of the pavement, and it is measured in inches. Area alone does not tell you how much material is needed. The amount of material depends on volume, which is area multiplied by thickness. Because thickness is usually written in inches, convert it to feet by dividing by 12 before multiplying. As a simple illustration only, 100 square feet at 3 inches thick is 100 times 3 divided by 12, or 25 cubic feet.

This is why a bid should state the thickness of each layer. Two areas of the same size can need very different amounts of material if one is designed thicker than the other.

Why are some materials priced by the ton?

Asphalt and crushed stone are often sold by weight, measured in tons, because weight is a consistent way to buy loose and bulk material. A ton of material covers a different area depending on how thickly it is spread and how dense it is. That is why a bid that lists tons should also show the target area and thickness, so you can confirm the quantities make sense.

How can I check a bid's quantities?

Start with the area in square feet or square yards, confirm the thickness, and then check that the tonnage is reasonable for those figures. If the calculation is not shown, ask the contractor to explain it. Ask for units on every line so you are comparing like with like, and make sure the area in the bid matches the area you measured or discussed on site.

What about linear feet?

Linear feet measure length in a straight line, not area. Items such as edging, curbing, and the length of a driveway apron are usually measured this way. Confirm which items in a bid are priced by area and which are priced by length, and do not add them together as if they were the same unit.

Frequently asked questions

Is one square yard the same as one square foot?

No. One square yard equals 9 square feet, so it is a much larger unit. Check the unit on each line of a bid before comparing totals.

Why do tons and square yards give different answers?

They measure different things. Tons measure weight, while square yards measure area. Converting between them depends on thickness and the density of the material, so a bid should explain how the quantities were calculated.

Do I need to do the math myself?

No, but checking a few numbers helps you catch errors. Ask for the area, thickness, and material units on each line, and ask about any figure you cannot trace back to the measurements.

Bruck Construction provides free estimates for asphalt and concrete projects in Columbus and central Ohio, and its written estimates list the units used. Request a free estimate to have your measurements reviewed.