How much ready-mix concrete should I order?
Ready-mix is usually ordered in cubic yards. Calculate project volume, add a practical waste buffer, then discuss rounding, minimum order size, and delivery timing with the supplier.
Ready-mix order planning
Suppliers may have minimum loads, short-load fees, delivery windows, truck access limits, and rounding rules. The calculator gives a quantity estimate, not a supplier quote.
Before the truck arrives
Forms, base prep, reinforcement, access, tools, finishers, and weather timing should be ready before delivery. Concrete quantity does not solve placement logistics.
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
- Ready mix is commonly ordered by cubic yard.
- Thickness is entered in inches.
- Confirm minimum order and delivery rules with the supplier.
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 Ready Mix 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 ready mix 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.
How is ready-mix concrete measured?
Ready-mix concrete is commonly ordered by cubic yard. One cubic yard equals 27 cubic feet.
Should I round up my ready-mix order?
Usually yes. Ask the supplier how they handle order increments, minimums, and short-load fees.
Does this include delivery cost?
No. It estimates quantity only. Delivery, short-load, pump, and scheduling fees vary by supplier.
Can I use bags instead of ready-mix?
For small pours, maybe. For larger volumes, compare the bag count, labor, mixing time, and ready-mix supplier minimums.
What is the example ready mix concrete result?
Using the default inputs, the example result is about 3.26 cubic yards. The calculation uses slab length, width, thickness, and waste.
Related calculators
This calculator is for planning estimates only. Verify final quantities with product labels, project conditions, and a qualified professional when accuracy matters.