Concrete for a 20×20 Slab — How Many Yards?
A 20×20 foot slab is typical for a two-car garage floor, large patio, or basketball court. At 4 inches thick, this slab requires 133.3 cubic feet (4.94 cubic yards). With a 10% waste factor, plan for 146.7 cubic feet. At this size, a ready-mix truck delivery is usually more economical than bags.
Quick Answer
Project Type
slab
Quantity
1
Includes Waste
10% factor
Use the full calculator below for custom dimensions, multiple zones, cost estimates, and to adjust the waste factor.
Concrete Calculator
Select your project type, enter dimensions, and get instant results with bag counts, weight, and cost.
Zone 1
Results
Total Volume
0.00 cu ft
0.00 cu yd
60 lb Bags
0
80 lb Bags
0
Total Weight
0 lbs
(0.00 tons)
💡 Ready-Mix Recommended
At 1+ cubic yard, truck delivery ($125–$175/yd) is usually cheaper and easier than mixing bags by hand.
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| freeconcretecalc.com · CALCULATION RECEIPT |
| Zone | Type | Dimensions | Qty | Volume (cu ft) |
|---|
Total Volume — | Cubic Yards — | Total Weight — |
60 lb Bags — | 80 lb Bags — | Est. Cost — |