Concrete Calculator
Calculate concrete for slabs, driveways, patios, and footings.
Last updated: January 15, 2026
Enter Measurements
Results
Concrete:1.23 cu yd
Area:100 sq ft
Volume:33.33 cu ft
Weight:5,000 lbs
Bags:56 x 80lb
Order 1.35 cu yd (+10% waste)
How to Use This Calculator
- Pick your project type - Slab, driveway, patio, sidewalk, or footing. This auto-sets the right thickness for you.
- Choose your shape - Rectangle works for most stuff, circle for round pads, triangle for those weird corners.
- Punch in your dimensions - Length and width in feet or inches. Measure twice, order once!
- Set the thickness - Use the presets (4", 5", 6") or go custom. Heads up: driveways need at least 5 inches.
- Get your numbers - Cubic yards for ready-mix orders, bag counts for DIY. Don't forget to add 10% for waste.
How We Calculate
Volume (cu ft) = Length x Width x Thickness
Cubic Yards = Volume (cu ft) / 27
Example Calculation:
- Slab: 10 ft x 10 ft x 4 inches thick
- Thickness in feet: 4" / 12 = 0.333 ft
- Volume: 10 x 10 x 0.333 = 33.3 cu ft
- Cubic yards: 33.3 / 27 = 1.23 cu yd
- 80lb bags: 33.3 / 0.60 = 56 bags
Concrete Bag Yields:
40 lb
0.30 cu ft
50 lb
0.375 cu ft
60 lb
0.45 cu ft
80 lb
0.60 cu ft
Formula based on ACI (American Concrete Institute) standards. Bag yields from Quikrete and Sakrete product specifications. Learn more