Area
A cul-de-sac is a circle and a corner lot rarely squares off. Measuring round work as a rectangle is where the quantity goes wrong, not the arithmetic.
Asphalt tonnage
Paving is measured by the square yard and bought by the ton. This is the step between.
Pounds per square yard per inch is the mix, and it isn't fixed — 110 is the number the trade has used for decades, but a coarse base mix weighs less than a surface course and the plant knows theirs. Thickness is compacted, not what leaves the paver.
Divide by nine, not three
A yard is three feet, so a square yard is three feet by three feet — nine square feet. Dividing square feet by three instead of nine is the single most common error in the conversion, and it leaves you ordering a third of what the job needs.
The other one worth memorising is 43,560 square feet to the acre. On sitework it comes up constantly: disturbed area sets the erosion control permit, and seed, straw and matting are all priced by the acre.
Quick conversions
| From | To | Multiply by |
|---|---|---|
| Square feet | Square yards | ÷ 9 |
| Square yards | Square feet | × 9 |
| Square feet | Acres | ÷ 43,560 |
| Acres | Square feet | × 43,560 |
| Square yards | Acres | ÷ 4,840 |
The shapes that cost money
Rectangles are the easy part and rarely the expensive part. A cul-de-sac bulb is a circle: diameter × diameter × 0.7854. A 90 foot bulb is about 6,362 square feet — 707 square yards. Call it 90 by 90 and you have just bought 27 percent more asphalt than the job takes, which is real money at paving prices.
Odd lots break down into rectangles and triangles. Split them, figure each piece, add them up. That beats averaging the width by eye every time, especially on a corner lot where the two frontages aren't parallel.
Why paving is in square yards
Convention, and one convenient number: a square yard of asphalt an inch thick is exactly 0.75 cubic feet. Compacted hot mix runs around 145 pounds per cubic foot, so that square yard inch weighs roughly 110 pounds — which is the figure the trade has used for as long as anyone can remember.
So square yards × inches × 110 ÷ 2,000 is your tonnage. A 1,000 square yard lot at 2 inches is about 110 tons. Get the poundage from the plant when you can — a coarse base mix is lighter than a surface course, and the thickness in that formula is compacted, not what leaves the paver.
Questions people ask
How do you convert square feet to square yards?
Divide by nine. A yard is three feet, so a square yard is three by three — nine square feet, not three. Dividing by three is the most common mistake in the conversion and it leaves you a third of the quantity you needed.
How many square feet are in an acre?
43,560. It is worth knowing by heart on sitework, because disturbed area drives the erosion control permit and the seeding quantity, and both are priced by the acre.
Why is paving measured in square yards?
Convention, mostly, and the fact that a square yard an inch thick is a convenient 0.75 cubic feet. Plans note pavement in square yards, plants sell the mix by the ton, and the number tying them together is the weight of a square yard at one inch.
How many tons of asphalt do I need?
Multiply square yards by the compacted thickness in inches, then by about 110 pounds, then divide by 2,000. A 1,000 square yard lot at 2 inches is roughly 110 tons. Confirm the poundage with the plant — a base mix and a surface course are not the same weight.
How do you figure the area of a cul-de-sac?
As a circle: radius times radius times pi, or diameter squared times 0.7854. A 90 foot diameter bulb is about 6,362 square feet, or 707 square yards. Measuring it as a 90 by 90 square would have you buying 27 percent more than the job takes.
Area is where a bid starts, not where it ends
Every one of these numbers becomes a line with a production rate, a crew and a markup behind it. DirtIQ takes quantities off the plans and prices them from your own costs, for excavation, grading and site utility contractors.
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