Concrete Patio Calculator
Estimate concrete volume, full bags, surface area, perimeter, placed weight and cost for a rectangular patio slab.
Default project preview
2.61 yd³
Concrete bags
118
Base volume
2.37 yd³
Patio area
192 ft²
Form perimeter
56 ft
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Patio length
Enter this project assumption in ft. The current imperial default is 16 ft.
Patio width
Enter this project assumption in ft. The current imperial default is 12 ft.
Slab thickness
Enter this project assumption in in. The current imperial default is 4 in.
Extra allowance
Enter this project assumption in %. The current imperial default is 10 %. Minimum: 0. Maximum: 50.
Concrete yield per bag
Enter this project assumption in ft³. The current imperial default is 0.6 ft³.
Ready-mix price
Enter this project assumption in per yd³. The current imperial default is 165 per yd³. Minimum: 0.
Price per bag
Enter this project assumption in a unitless value. The current imperial default is 7. Minimum: 0.
How to read the outputs
Concrete bags
rounded full bags. Default preview: 118.
Base volume
before allowance. Default preview: 2.37 yd³.
Patio area
finished surface. Default preview: 192 ft².
Form perimeter
outside edges. Default preview: 56 ft.
Placed weight
planning density. Default preview: 10,548 lb.
Cost comparison
ready-mix / bags. Default preview: $430.22 / $826.00.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Volume = length × width × slab thickness. Order volume applies the allowance before conversion to ready-mix units or full concrete bags.
Reviewed project guidance
How to use this estimate in a real project
Last reviewed: July 29, 2026
Use this calculator to estimate patio concrete volume and purchasing quantity from footprint, thickness and waste. It is intended for material planning while slope, drainage, joints and foundation conditions are handled separately.
Calculation steps
- 1Measure the finished patio footprint.
- 2Use the project-specified slab thickness.
- 3Add any thickened edges as separate shapes.
- 4Apply allowance and round according to supplier practice.
Worked numerical example
A 16 ft × 14 ft patio at 4 in thick contains 74.7 ft³, or 2.77 yd³. With 10% allowance, plan roughly 3.05 yd³ before supplier increments.
Purchasing and rounding
Ready-mix quantity should account for truck minimums, access and placement rate. Bag counts must use the yield printed on the selected mix.
Interpret the result
The estimate represents wet concrete volume. It excludes excavation, compacted base, reinforcement, forms, joints and finishing materials.
Page-specific assumptions
- Uniform slab thickness.
- Simple plan geometry or separately combined shapes.
- No volume deduction for reinforcement.
- Stable dimensions after form placement.
Common mistakes
- Measuring only the furniture area.
- Forgetting thickened edges.
- Using dry material weight as concrete volume.
- Ignoring drainage slope when setting forms.
Primary and technical references
BuildMeter provides planning estimates, not engineering, architectural, electrical, mechanical, plumbing, permit or code approval. Review the methodology and verify final decisions with product documentation and qualified professionals.
FAQ
Concrete Patio Calculator questions
Should a patio slope away from the building?+
Outdoor slabs commonly need positive drainage, but the required slope and finished elevations depend on the site and local requirements.
Does this include a gravel base?+
No. Base aggregate, excavation and compaction should be estimated separately.
Are control joints included?+
No. Joint layout depends on slab geometry, thickness and construction details.