What This Section Is For
These calculators answer the question you have standing in a builders' yard or on the phone to a supplier: how much of it do I buy. They work in the units the trade actually sells in, which is rarely the unit you measured in. Concrete is priced by the cubic yard but poured to a thickness in inches. Aggregate is sold by the ton but specified by the yard. Roofing is sold by the square, which is 100 square feet and not a square of anything. Getting from one to the other is where the money is lost.
Every page shows its arithmetic. If a page gives you a number you cannot reproduce on paper, that is a fault in the page, not a feature of the calculator.
Conversions Every Job Runs On
These are definitions, not estimates, so they are the same on every site and in every state.
| Unit | Equals | Where it bites |
|---|---|---|
| 1 cubic yard | 27 cubic feet | Concrete and aggregate are both sold this way. A cubic yard is not three cubic feet. |
| 1 cubic foot | 1,728 cubic inches | Bag yields are printed in cubic feet, so every inch has to become a foot first. |
| 1 inch | 1 ÷ 12 of a foot | Slab thickness. Entering 4 instead of 0.333 orders twelve times the concrete. |
| 1 square (roofing) | 100 square feet | Shingles are sold by the square and delivered in bundles. |
| 1 board foot | 144 cubic inches | Lumber priced by volume, which is 1 foot by 1 foot by 1 inch. |
| 1 short ton | 2,000 pounds | Aggregate is weighed, so tonnage depends on the material, not just the volume. |
| 1 acre | 43,560 square feet | Site areas, clearing and grading. |
What These Pages Will Not Tell You
Quantity is arithmetic and these pages will give you it. Three things are not arithmetic, and no calculator should pretend otherwise.
- How thick, how strong, how much steel. That is set by the loads and by the building code your project falls under. It belongs with your local building department or your engineer.
- What it costs. Suppliers set their own full load sizes, minimums and part load charges, and they differ by plant and by region. Take your quantity to the rate sheet.
- What the ground will do. Sub-base, drainage and frost depth decide whether a correct quantity of concrete turns into a slab that lasts.
For the plain geometry underneath all of it, the volume calculator and the area calculator take any shape in either unit system, and the length and weight converters handle the rest.
Construction Questions
How many cubic feet are in a cubic yard?
27. A yard is 3 feet, and volume cubes the linear factor, so 3 × 3 × 3 = 27 cubic feet. This single conversion sits behind concrete, aggregate, topsoil and fill quantities, and treating a cubic yard as 3 cubic feet is the most expensive arithmetic mistake on a small site.
Why is roofing measured in squares?
A square is a trade unit meaning 100 square feet of roof surface. It is not a square shape and it has no side length. Shingles are priced and delivered against it, so a roof of 2,400 square feet is 24 squares. How many bundles make a square is set by the product, so take it from the wrapper rather than from a rule of thumb. Roof surface is also larger than the footprint of the house, because the slope stretches it.
Why does the supplier want tons when I measured in yards?
Because aggregate is weighed on a bridge, not measured in a box. Converting the two needs the density of that particular material, and gravel, crushed stone, sand and topsoil all weigh differently, wet differently again. Give a supplier the volume in cubic yards and the material by name, and let them convert it, or ask them for the density they bill at.
Do these calculators tell me what the job will cost?
No, and that is deliberate. Quantity is arithmetic and the same everywhere; price is a rate sheet that differs by plant, by region and by week. What these pages do is give you a quantity you can hand to a supplier in the unit they sell in, which is the number you need before anyone can quote you.