Concrete Patio Calculator
Calculate concrete for a rectangular patio, with waste, bag equivalent and supplier order rounding.
Quick answer
A 12 × 16 ft patio at 4 in needs 2.37 yd³ exact. With 10% extra it is 2.61 yd³, or 3.0 yd³ at a 0.5 yd³ supplier increment.
How this estimate works
Length × width × thickness in feet ÷ 27 gives exact cubic yards. Add your allowance, then round up to the supplier increment you entered. Bags use an example yield of 0.60 ft³ per 80 lb bag.
Before you order
Measure finished patio dimensions. If the edge is thicker or the patio is L-shaped, split it into separate pours in the multi-pour calculator. This tool estimates volume, not structural design or drainage slope.
Ask the supplier about minimum loads, order increments and delivery charges. The suggested quantity is a rounding aid, not a supplier quote.
Common patio sizes
Each row assumes a uniform 4 in rectangular pour, 10% extra and 0.60 ft³ of finished concrete per 80 lb bag. Actual product yield and patio thickness can differ.
| Finished area | Exact at 4 in | With 10% extra | 80 lb bags |
|---|---|---|---|
| 8 × 10 ft | 0.99 yd³ | 1.09 yd³ | 49 |
| 10 × 12 ft | 1.48 yd³ | 1.63 yd³ | 74 |
| 12 × 12 ft | 1.78 yd³ | 1.96 yd³ | 88 |
| 12 × 16 ft | 2.37 yd³ | 2.61 yd³ | 118 |
| 16 × 20 ft | 3.95 yd³ | 4.35 yd³ | 196 |
For a 12 × 16 ft patio, 192 ft² × 4/12 ft = 64 ft³. That is 2.37 yd³ exact and 2.61 yd³ with 10% extra. A supplier accepting only 0.5 yd³ increments would round it to 3.0 yd³; confirm that increment before ordering.
What to measure beyond the rectangle
Curved edges, steps and built-in pads are easy to omit from a simple length × width entry. Split a patio outline into non-overlapping rectangles, or use the round slab calculator for a full circle. A circular cutout should be subtracted from the area before estimating, not treated as a separate positive pour.
A gravel base and reinforcement are separate material plans. Use the gravel base calculator and rebar grid calculator after the finished patio dimensions are settled. This tool does not choose drainage slope or structural thickness.
Questions before you order
Does this calculate an L-shaped patio?
Not in one entry. Divide the L shape into two rectangles that do not overlap and add them in the multi-pour estimator.
Why does the suggested supplier order exceed the volume with extra?
The suggestion rounds upward to your entered ordering increment. It does not assume a supplier minimum load.
Are the bag counts exact for every mix?
No. They assume 0.60 ft³ finished yield per 80 lb bag; use the actual yield printed on your mix.
Continue planning
Content and calculator by pourmeasure. Formula and assumption notes: methodology and sources. Updated October 2026. No independent engineering review is claimed.