How to convert concrete square feet to yards
Concrete square feet describe the surface area, but concrete is ordered by volume. Multiply square feet by thickness in feet, divide by 27, then add waste if needed. In this calculator, length and width create the square footage, and thickness turns that area into cubic yards.
Square feet alone is not enough
A 500 sq ft patio and a 500 sq ft driveway do not always need the same concrete. At 4 inches thick, 500 sq ft is about 6.17 cubic yards before waste. At 6 inches thick, the same area is about 9.26 cubic yards before waste.
Concrete coverage by thickness
One cubic yard of concrete covers about 81 sq ft at 4 inches thick, about 65 sq ft at 5 inches thick, and about 54 sq ft at 6 inches thick. Use these as planning checks, then run your actual length, width, thickness, and waste.
When a square-foot concrete calculator helps
This page is useful when plans, listings, or estimates give you floor area in square feet but the concrete supplier wants cubic yards. Break irregular areas into rectangles, calculate each area, then add the cubic yards together.
Concrete coverage by thickness
Coverage assumes 1 cubic yard of concrete, which is 27 cubic feet. Waste is not included.
| Thickness | Sq ft covered by 1 cu yd | Sq ft covered by 2 cu yd |
|---|---|---|
| 3 in | 108 sq ft | 216 sq ft |
| 4 in | 81 sq ft | 162 sq ft |
| 5 in | 65 sq ft | 130 sq ft |
| 6 in | 54 sq ft | 108 sq ft |
| 8 in | 41 sq ft | 81 sq ft |
Before you calculate
- Measure the actual formed length and width in feet.
- Enter slab thickness in inches, then handle thickened edges or footings as separate estimates.
- Break irregular slabs into rectangles so the volume calculation stays transparent.
Common mistakes
- Using square feet without converting thickness into volume.
- Missing thickened edges, turndowns, steps, or separate pads.
- Ordering exactly the calculated amount with no allowance for site variation.
Formula
cubic yards = (length * width * (thickness / 12) / 27) * (1 + wastePercent / 100)
Assumptions
- Length and width determine square footage.
- Thickness is entered in inches.
- The result is cubic yards of concrete.
Example
Estimated concrete needed (cubic yards): 3.26 cubic yards
How to use this calculator
- Enter length in ft.
- Enter width in ft.
- Enter thickness in in.
- Enter waste in %.
- Review the live estimate and compare it with the example result.
- Check the formula, assumptions, product labels, and site conditions before using the Sq Ft to Cubic Yards Concrete Calculator result to plan materials.
Before you buy materials
- Compare cubic yards, cubic feet, and bag counts before deciding between ready-mix and bags.
- Confirm final slab details with plans, product labels, or a qualified professional when accuracy matters.
FAQ
What is the example sq ft to cubic yards concrete cubic-yard result?
Use length, width, thickness or depth, and waste, then calculate the planning result. In the default example, the result is 3.26 cubic yards.
What formula converts sq ft to concrete yards?
Use cubic yards = (square feet x (thickness inches / 12)) / 27, then multiply by 1 plus the waste percent if you are adding waste.
How many yards of concrete for 500 sq ft at 4 inches?
At 4 inches thick, 500 sq ft needs about 6.17 cubic yards before waste. With 10% waste, plan about 6.79 cubic yards.
How many square feet does 1 yard of concrete cover?
One cubic yard covers about 81 sq ft at 4 inches thick, 65 sq ft at 5 inches thick, or 54 sq ft at 6 inches thick.
Can I order concrete from square feet only?
No. Square footage is only area. You also need slab thickness to calculate concrete volume in cubic yards.
Related calculators
This calculator is for planning estimates only. Verify final quantities with product labels, project conditions, and a qualified professional when accuracy matters.