Free US quantity worksheet
Concrete Calculator for Volume, Cubic Yards and Bags
Calculate a rectangular slab or trench, solid round column or round tube from your dimensions. See geometric volume, your chosen extra allowance, cubic yards and a whole-bag estimate using the product yield you enter.
Starting figures illustrate the calculation. Replace them with verified measurements and the actual product details. Allowances are your choice, not a recommended rate.
Your quantity result
- Geometric volume before allowance (cu ft)
- 20
- Volume with allowance (cu ft)
- 22
- Volume with allowance (cu yd)
- 0.815
- Whole bags with allowance
- 37
Volume planning only. The starting 0.60 cu ft per bag is the approximate yield for an 80 lb bag of QUIKRETE Concrete Mix 1101, not every concrete product. This does not select a mix, thickness, reinforcement or structural design.
Calculations stay in this browser. No signup or email is needed.
Convert inches before calculating the volume
For a rectangle, volume in cubic feet = length in feet × width in feet × depth in inches / 12. A solid round section uses π × (diameter in feet / 2)² × height in feet. A tube subtracts the inner circular area before multiplying by height.
One cubic yard is 27 cubic feet. Apply your selected allowance once, then divide by 27 for cubic yards or by the actual bag yield for bag quantity. Whole bags round up, not down.
For a 10 ft by 6 ft slab at an entered 4-inch thickness, geometric volume is 20 cu ft. With no extra allowance and an entered 0.60 cu ft yield, 20 / 0.60 requires 34 whole bags. This example does not recommend that thickness or product for a job.
Bag weight does not establish a universal yield
The QUIKRETE Concrete Mix 1101 data sheet lists approximate yields of 0.30 cu ft for 40 lb, 0.375 for 50 lb, 0.45 for 60 lb, 0.60 for 80 lb and 0.675 for 90 lb. These are identified product values; use the actual package details for another mix.
This worksheet does not design a slab, select strength, reinforcement or foundations, or estimate delivery access and minimum-order charges. Confirm the dimensions, product, allowance and ordering method for the actual project.