Quantity · Ready-mix order
Ready Mix Concrete Calculator
Convert slab dimensions to cubic yards for a ready-mix order — with waste, quarter-yard rounding, and a short-load warning before you call the plant.
Pour dimensions
Order this many yards
3.25cy
Rounded up in ¼ cy steps from 3.11 cy with waste
- Raw volume
- 2.96 cy
- With waste
- 3.11 cy
- Area
- 240 sq ft
Short load: under 4 cy. Plants often add $50–150. Confirm when you call.
Material only (delivered)
$473–$800
Ready-mix $130–200/cy + short-load surcharge. Labor and forms not included — use the cost calculator for installed totals.
Breakdown
- 20 × 12 × (4 ÷ 12) = 80 cu ft
- ÷ 27 = 2.96 cy raw
- × (1 + 5%) = 3.11 cy
- Round up to 3.25 cy
Price data updated . National US ranges from published supplier and contractor averages. Not a bid. Local quotes vary.
How ready-mix yardage is calculated
Ready-mix is sold by the cubic yard. Get the volume right first; price and labor come second.
cu ft = length_ft × width_ft × (thickness_in ÷ 12) cu yd = cu ft ÷ 27 with waste = cu yd × (1 + waste %) order yards = ceil(with waste × 4) ÷ 4 ← ¼ cy steps
Worked example. A 20 × 12 ft × 4 in slab is 80 cu ft → 2.96 cy. With 5% waste → 3.11 cy, rounded to 3.25 cy for the plant. That sits near the short-load line — confirm surcharge policy with your plant.
Ready-mix order cues
Plants often round to quarter yards. Short loads under ~4 cy may carry a surcharge.
| Topic | Guidance |
|---|---|
| Order step | Round up to next 0.25 cy |
| Waste | Often 5% on simple rectangles |
| Short load | Under ~4 cy — expect surcharge |
| Bags crossover | Below ~1 cy bags may win |
Ready Mix Concrete calculator FAQ
- How do I calculate ready-mix concrete in cubic yards?
- Multiply length × width × (thickness in inches ÷ 12) to get cubic feet, then divide by 27. Add a waste percentage (often 5%) so you do not run short mid-pour. Plants commonly take orders in quarter-yard steps — this calculator rounds up to the next 0.25 cy.
- How much extra ready-mix should I order?
- Five percent covers most rectangular slabs with a decent subgrade. Bumpy excavation, thick edges, or first-time pours may need closer to 10%. Running short costs more than a leftover wheelbarrow load — leftover can become a pad or pier.
- Does this include labor to place the concrete?
- No. This page sizes the truck order and shows a delivered-material range only. For installed cost with labor, rebar, and forms, open the concrete cost calculator.
- What is a short-load fee on ready-mix?
- Many plants surcharge orders under about 4 cubic yards because the truck still makes the trip. Confirm your plant’s minimum. Below roughly 1 cy, bagged mix is often cheaper than calling a truck.