Patio concrete calculator
Patio concrete calculator
For a concrete patio, multiply patio length by width by thickness in feet, then divide by 27 for cubic yards. A 12 ft by 16 ft patio at 4 inches thick needs about 2.38 cubic yards before waste, or about 118 80-lb bags with a 10% buying allowance.
Quick answer
| Common patio thickness | 4 inches for normal pedestrian patios |
|---|---|
| Hot tub or outdoor kitchen | Often 5-6 inches or a separate reinforced pad |
| 12x16 patio example | 2.38 yd3 before waste / 118 80-lb bags with 10% waste |
| Default finish | Broom or light texture for exterior traction |
Concrete for common patio sizes
These estimates assume a 4 inch slab unless noted. The order and cost columns include 10% extra concrete.
| Scenario | Dimensions | Base volume | 80-lb bags | Ready-mix with 10% | Bagged with 10% |
|---|---|---|---|---|---|
| Small seating patio Compact seating pad or grill landing. | 10 ft x 10 ft x 4 in | 1.24 yd3 | 56 bags before waste | 1.36 yd3 / $204 | 62 bags / $310 |
| Square dining patio Works for a small table and chairs. | 12 ft x 12 ft x 4 in | 1.78 yd3 | 80 bags before waste | 1.96 yd3 / $294 | 89 bags / $445 |
| Dining patio Common backyard dining footprint. | 12 ft x 16 ft x 4 in | 2.38 yd3 | 107 bags before waste | 2.61 yd3 / $392 | 118 bags / $590 |
| Large patio Often ready-mix territory because bag counts are high. | 16 ft x 20 ft x 4 in | 3.96 yd3 | 178 bags before waste | 4.35 yd3 / $653 | 196 bags / $980 |
| Hot tub corner Use manufacturer load requirements for the final pad. | 8 ft x 8 ft x 6 in | 1.19 yd3 | 54 bags before waste | 1.31 yd3 / $197 | 59 bags / $295 |
Interactive calculator
Patio concrete calculator
Use the calculator for exact length, width, and thickness. Split L-shaped patios, grill pads, and hot tub pads into separate sections when thickness changes.
Use Quick estimates for common patios, then adjust thickness for hot tub or kitchen pads.
How to decide what to buy
Patio thickness is a load decision
Four inches is a common planning thickness for walking and furniture. Hot tubs, masonry kitchens, fireplaces, or vehicle access can require a thicker or reinforced section.
Finish affects cost
A broom finish is the simple planning default. Stamped, colored, exposed aggregate, or polished finishes can add more cost than the concrete volume itself.
Drainage belongs in the estimate
Patios need slope away from the house and should not trap water at doors, siding, or steps. Drainage changes excavation, base, forms, and sometimes the slab shape.
Material checklist
- Concrete yards and 80-lb bag count from patio dimensions
- 10% extra for spillage, depth variation, and edges
- Compacted base, forms, stakes, control joints, curing method, and finish tools
- Reinforcement or thicker pad where loads are higher than normal patio use
Cost assumptions
The table uses $150 per cubic yard for ready-mix and $5 per 80-lb bag. It is a planning comparison, not a delivered quote.
- The concrete-only cost in the table uses $150 per cubic yard for ready-mix and $5 per 80-lb bag.
- Installed patio bids can include excavation, base stone, forms, reinforcement, finishing, curing, and cleanup.
- Large patios usually favor ready-mix because bag mixing can create finish timing problems.
Common mistakes
- Treating a hot tub pad like a normal walking patio.
- Forgetting slope away from the house.
- Using one average thickness when the patio includes steps, thickened edges, or a separate equipment pad.
- Comparing stamped-concrete quotes with plain broom-finish material estimates.
Formula and methodology
Volume in cubic feet equals length x width x thickness in feet. Cubic yards equal cubic feet / 27. An 80-lb premix bag is estimated at 0.60 cubic feet. Ready-mix order size and bagged cost use a 10% buying allowance for field variation.