Concrete Patio Calculator
Calculate cubic yards of concrete for a patio slab from its length, width, and depth, plus material cost at your price per yard.
How this calculator works
A patio slab is a straightforward rectangular pour: length, width, and a consistent depth across the whole footprint. This calculator multiplies those three measurements to get cubic feet, then divides by 27 for the cubic yards you’d order from a ready-mix supplier.
Formula: Cubic yards = (Length ft × Width ft × Depth ft) ÷ 27.
Worked example
A 12 ft × 12 ft patio at a 4-inch depth:
- Depth in feet: 4 ÷ 12 = 0.3333 ft
- Cubic yards: (12 × 12 × 0.3333) ÷ 27 ≈ 1.78 yd³
- At $150/yd³, that’s $266.67 before waste.
Cost reference
| Patio size | Depth | Cubic yards | Cost at $150/yd³ |
|---|---|---|---|
| 6 ft × 6 ft | 4 in | 0.44 yd³ | $66.67 |
| 12 ft × 12 ft | 4 in | 1.78 yd³ | $266.67 |
| 24 ft × 24 ft | 4 in | 7.11 yd³ | $1,066.67 |
How to measure your patio
Measure the finished patio footprint’s length and width in feet at the surface, and use the poured slab thickness as the depth rather than the depth of any excavation or gravel base beneath it. If the patio includes a curved or angled edge, treat it as the largest enclosing rectangle for ordering purposes — a small overage is cheaper than a truck coming up short.
Frequently asked questions
What depth should a concrete patio be?
4 inches is the standard depth for a patio carrying foot traffic, furniture, and grills — the default this calculator uses. If you plan to drive or park a vehicle on part of the patio, thicken that section to 5-6 inches to handle the added load.
Does a patio need rebar or wire mesh?
Most residential patios use welded wire mesh or rebar for crack control, especially on patios over roughly 10 ft in any dimension or in areas with expansive or poorly compacted soil. This calculator estimates concrete volume only — reinforcement is a separate material cost that depends on your local soil and code requirements.
Broom finish or stamped concrete — does it change how much concrete I need?
No, the volume of concrete needed is the same either way since it's determined by the slab's footprint and depth, not the surface treatment. Stamped and decorative finishes do add labor cost and sometimes require a slightly richer mix design, but the cubic yardage calculation itself doesn't change.
How do I plan for expansion joints on a patio?
Expansion or control joints are typically placed every 8-12 feet in both directions to control where the slab cracks as it shrinks while curing, but they don't change the total concrete volume — the joints are cut or formed into the same poured slab, not separate pours.
Estimates only. Verify quantities with your supplier before purchasing.