What concrete yardage means
Concrete yardage means cubic yards of concrete, not square yards. One cubic yard is 27 cubic feet. Ready-mix orders are usually discussed in cubic yards because the truck delivers volume, not area.
How to calculate concrete yardage
Multiply length by width, convert thickness from inches to feet, divide by 27, then add your waste percentage. For example, a 20 x 12 ft slab at 4 inches thick is about 2.96 cubic yards before waste and about 3.26 cubic yards with 10% waste.
Rounding yardage for ordering
Use the calculator result as a planning number, then ask the supplier how they handle minimum orders, short-load fees, truck spacing, and rounding. Do not reduce the order below the measured volume just to match a round number.
Yardage checks for common flatwork
A 10 x 10 ft slab at 4 inches is about 1.23 cubic yards before waste. A 16 x 20 ft patio at 4 inches is about 3.95 cubic yards before waste. A 12 x 40 ft driveway strip at 4 inches is about 5.93 cubic yards before waste.
Common concrete slab sizes
Cubic yards below are before waste. Add your project waste percentage before ordering.
| Slab size | 4 in thick | 5 in thick | 6 in thick |
|---|---|---|---|
| 10 ft x 10 ft | 1.23 cu yd | 1.54 cu yd | 1.85 cu yd |
| 10 ft x 12 ft | 1.48 cu yd | 1.85 cu yd | 2.22 cu yd |
| 12 ft x 12 ft | 1.78 cu yd | 2.22 cu yd | 2.67 cu yd |
| 20 ft x 20 ft | 4.94 cu yd | 6.17 cu yd | 7.41 cu yd |
| 24 ft x 24 ft | 7.11 cu yd | 8.89 cu yd | 10.67 cu yd |
| 30 ft x 40 ft | 14.81 cu yd | 18.52 cu yd | 22.22 cu yd |
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
- Yardage means cubic yards.
- Thickness is entered in inches.
- The estimate assumes a rectangular area.
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 Concrete Calculator Yardage 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 concrete calculator yardage 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.
Is concrete yardage the same as cubic yards?
Yes. In concrete ordering, yardage usually means cubic yards. One cubic yard equals 27 cubic feet.
How do I calculate concrete yardage?
Use cubic yards = length x width x thickness in feet / 27, then add waste if needed. Thickness should be converted from inches to feet.
Should I round up concrete yardage?
Many projects include a waste buffer for base variation, form loss, and ordering variance. Confirm final rounding and minimum order rules with the ready-mix supplier.
Is yardage the same as square footage?
No. Square footage is area. Yardage is volume, so slab thickness must be included.
Related calculators
This calculator is for planning estimates only. Verify final quantities with product labels, project conditions, and a qualified professional when accuracy matters.