Concrete Patio Calculator
Estimate concrete volume, pre-mix bag counts, and material costs for backyard patios and outdoor living spaces. Enter patio dimensions and thickness for instant cubic yards and bags.
How to Use This Calculator
- Enter your dimensions — feet for lengths, inches for thickness.
- Adjust the options — waste percentage, bag size and your local concrete price.
- Read your results — volume, bags, weight and cost update live as you type.
The Formula
Patio volume (yd³) = (Length ft × Width ft × Thickness in ÷ 12) ÷ 27 Worked example: A 12 × 16 ft patio at 4 in (0.333 ft): 192 ft² × 0.333 = 64 ft³ ÷ 27 ≈ 2.37 yd³ — order 2.75 yd³ with waste.
Use this concrete patio calculator to determine exact cubic yardage, bag counts, and material costs for backyard patios and outdoor living spaces. A 4-inch slab thickness is standard for foot traffic and patio furniture, poured over a 4-inch compacted gravel base with a 1/4-inch per foot slope away from the house foundation for positive drainage.
For small patios under 100 square feet (approx. 1.25 cubic yards), buying 80 lb pre-mix bags is practical. For patios larger than 12 × 12 ft, ordering ready-mix delivery avoids the backbreaking labor of hand-mixing 50+ bags and ensures a uniform, monolithic slab finish.
Remember to install expansion joint material (isolation foam or asphalt impregnated fiber) wherever the concrete patio abuts the house foundation or exterior steps to prevent structural binding.
Frequently Asked Questions
Common questions about the concrete patio calculator.
How much concrete for a 12x12 patio?
A 12 × 12 ft patio at 4 inches thick requires 1.78 cubic yards (48 cubic feet), or about 80 bags of 80 lb pre-mix concrete before waste. Add 10% for subgrade irregularity.
Is 4 inches thick enough for a concrete patio?
Yes. 4 inches is the universal standard for residential patios, walkways, and shed bases carrying foot traffic, grills, and outdoor furniture.
How much slope should a patio have?
Slope the slab 1/4 inch per linear foot away from the house to ensure rainwater drains away from the building foundation.
Should I use bags or ready-mix for a patio?
Under 1.5 yards (approx. 10 × 10 ft), bags are cost-effective. For anything larger than 12 × 12 ft, ready-mix truck delivery is faster, stronger, and more economical.
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