Concrete Patio Calculator
To pour a 12 × 16 ft patio at 4 inches thick you need about 2.37 cubic yards of concrete plus 10% waste — roughly 118 bags of 80 lb mix, though ready-mix delivery is usually cheaper at that size.
Reviewed by The ponderloop teamUpdated 2026-07-11How we calculate
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0 cu yd + 0% waste = 0 cu yd
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How this number is calculated
0 cu yd (no waste added) ÷ 0.0222 cu yd per bag = 0 bags
Shopping list
- 80 lb concrete mix
- Mixing tub
- Finishing trowel
- Rebar
- Concrete sealer
- Concrete edger
0.0 cu yd — ~0% of a standard truck load
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Methodology & assumptions
Volume is calculated as patio length × width × (thickness in inches ÷ 12), then divided by 27 to convert cubic feet to cubic yards. A waste percentage is added for spillage and uneven subgrade, and the result is divided by the coverage per bag (about 0.0222 cu yd for an 80 lb bag) and rounded up to the next whole bag. Because patios often exceed 1 cubic yard, ready-mix delivery is frequently the more economical and practical option.
- ACI 318 concrete practice (waste allowance)
- Manufacturer bag-yield specs (80 lb ≈ 0.60 cu ft)
- Typical US ready-mix and bag price ranges, 2026
Worked examples
| Room | Result |
|---|---|
| 12 × 16 ft patio, 4 in thick, standard waste | 2.37 cu yd + 10% waste ≈ 2.61 cu yd → 118 bags |
| 10 × 20 ft patio, 4 in thick, minimal waste | 2.47 cu yd + 5% waste ≈ 2.59 cu yd → 117 bags |
| 14 × 14 ft patio, 4 in thick, standard waste | 2.42 cu yd + 10% waste ≈ 2.66 cu yd → 120 bags |
Frequently asked questions
- How much concrete do I need for a patio?
- Multiply the patio length by width in feet, multiply by the thickness in feet (inches divided by 12), then divide by 27 to convert cubic feet to cubic yards. Add 10% for waste, then divide by the coverage per bag (about 0.0222 cu yd for an 80 lb bag) and round up.
- How many bags of concrete are in a cubic yard?
- About 45 bags of 80 lb mix per cubic yard, since each bag yields roughly 0.60 cu ft and a cubic yard is 27 cu ft. A 60 lb bag yields about 0.45 cu ft (around 60 bags per cubic yard), and a 40 lb bag yields about 0.30 cu ft (around 90 bags per cubic yard).
- Is bagged concrete or ready-mix delivery cheaper for a patio?
- Most patios need well over 1 cubic yard once you multiply out length, width, and thickness — at that volume, ready-mix delivered by truck is usually cheaper per yard and dramatically less labor than mixing dozens of bags by hand. Bagged mix is more practical for small patios, repairs, or footings under about 1 cubic yard.
- Do I need control joints or a gravel base for a patio slab?
- Yes for both, though neither changes the concrete volume this calculator estimates. A compacted gravel base (typically 4 in.) improves drainage and reduces cracking, and control joints cut every 8-10 ft limit where cracks form as the slab cures and shifts with temperature.
- Should I round up or down when figuring out how many bags to buy?
- Always round up to a full bag. Running short mid-pour is a serious problem with concrete since it starts setting once mixed — cold joints from a delayed second batch weaken the slab.