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Concrete Yard Calculator
Ready-mix concrete is ordered by the cubic yard, so this calculator leads with the yard number: enter the length, width and thickness of your pour and get the yards to order, waste allowance included. Bag counts are shown as a backup for small pours, and an optional price per yard turns the answer into a ready-mix cost. For round slabs and other shapes, use the concrete slab calculator; for a general-purpose tool, the concrete calculator — all three run the same verified math.
Results update as you type. Estimates only — confirm final quantities before ordering.
The formula
Cubic yards = ft³ ÷ 27 • Bags = ft³ ÷ yield per bag
One cubic yard is 27 cubic feet — a cube 3 ft on each side. Spun out flat, one yard covers 162 ft² at 2 inches thick, 81 ft² at 4 inches, or 54 ft² at 6 inches, which is the quickest sanity check on any yard figure. The waste allowance (10% by default) is applied to the volume before the yardage and bag counts are worked out. Bag counts use the yields published in the QUIKRETE Concrete Mix data sheet: an 80 lb bag yields about 0.60 ft³, a 60 lb bag 0.45 ft³ and a 40 lb bag 0.30 ft³ — so one cubic yard is 45, 60 or 90 bags respectively. This is the same verified math as our concrete calculator, framed around the number a ready-mix dispatcher actually asks for.
Worked example
Example: a 20 ft × 10 ft driveway pour, 4 inches thick, 10% waste, ready-mix at $150 per yard.
- Raw volume: 20 × 10 × (4 ÷ 12) = 66.67 ft³
- With 10% waste: 73.33 ft³ ÷ 27 = 2.72 yd³ to order
- In bags that would be 73.33 ÷ 0.60 = 123 × 80 lb | ÷ 0.45 = 163 × 60 lb | ÷ 0.30 = 245 × 40 lb — which is why a pour this size goes on a truck
- Ready-mix cost: 2.72 × $150 = $407 for the concrete itself (delivery and short-load fees, if any, are extra)
The familiar 10 × 10 ft patio at 4 inches works out to 1.36 yd³ with the same waste allowance.
Reference chart
| Slab size | 4 in thick | 6 in thick |
|---|---|---|
| 8 × 8 ft | 0.87 yd³ | 1.30 yd³ |
| 10 × 10 ft | 1.36 yd³ | 2.04 yd³ |
| 10 × 20 ft | 2.72 yd³ | 4.07 yd³ |
| 12 × 24 ft | 3.91 yd³ | 5.87 yd³ |
| 20 × 20 ft | 5.43 yd³ | 8.15 yd³ |
| 24 × 24 ft | 7.82 yd³ | 11.73 yd³ |
Frequently asked questions
How many yards of concrete do I need for a 10x10 slab?
At 4 inches thick, a 10 x 10 ft slab holds 1.23 cubic yards before waste and 1.36 yd³ with the standard 10% waste allowance — order 1.5 yards if your supplier rounds to half yards. At 6 inches thick it is 2.04 yd³ with waste. In bags, the 4-inch slab is 62 x 80 lb bags.
How many yards of concrete are in a truck?
A standard ready-mix mixer truck carries 8–10 cubic yards (road weight limits often cap the practical load near 10). Smaller volumetric and mini-mixer trucks deliver roughly 1–4 yards and are aimed at exactly the small pours a full-size truck handles badly.
What is a short-load fee?
A surcharge suppliers add when an order falls below their minimum economical load — commonly under about 5 cubic yards. Supplier guides put the fee anywhere from about $50 to $200 depending on the company and how far under the minimum you are. It is always worth asking about before ordering 2–3 yards: sometimes ordering the minimum, or combining two small pours into one delivery, works out cheaper.
How many bags of concrete make a cubic yard?
At the published QUIKRETE yields, one cubic yard is 45 bags of 80 lb mix, 60 bags of 60 lb, or 90 bags of 40 lb — before waste. That is the practical dividing line between bags and a truck: above roughly one yard, ready-mix is usually cheaper and far less labor than mixing 45+ heavy bags.
Should I round my yard order up or down?
Always up. Suppliers batch in quarter- or half-yard steps, so round the calculator's figure up to the next step (2.72 yd³ becomes 2.75 or 3). Running short mid-pour means a second delivery, a cold joint and mismatched color; a small leftover costs a fraction of that. Keep the waste allowance at 10% for formed, level bases and raise it for hand-dug or uneven ones.
Related calculators
- Concrete Calculator — Cubic yards and bag counts for slabs, patios and pads.
- Concrete Slab Calculator — Yards and bags for a concrete slab — rectangular or round.
- Gravel Calculator — Gravel in cubic yards and tons, by depth and density.
Sources & method: 27 ft³ = 1 yd³; bag yields from the QUIKRETE Concrete Mix No. 1101 technical data sheet (0.30 / 0.45 / 0.60 ft³ per 40 / 60 / 80 lb bag); mixer-truck capacity 8–10 yd³ and short-load practice (minimums commonly around 5 yd³, fees roughly $50–$200) per ready-mix supplier guides fetched October 2026. Yardage verified identical to this site's Concrete Calculator for the same inputs.