Estimate Concrete by Shape, Bags, Yards and Truckloads
Figure cubic yards for rectangular and triangular slabs, walls, footings, columns, round pads, tube forms, curbs and concrete steps. Every result shows the shape formula, waste-adjusted order, bags, truckloads, weight and cost.
Project geometry
Ordering assumptions
Bag and price options
Selected concrete shape
Concrete quantity
How to figure yards for concrete
Calculate the shape volume in cubic feet, multiply by quantity, and divide by 27 because one cubic yard contains 27 cubic feet. Add an explicit overage for grade variation, form leakage and handling. The calculator never hides this allowance inside the base geometry.
Triangular concrete slabs and footings
For a triangular plan, enter the triangle base as Length, the perpendicular plan height as Width, and the slab thickness separately. The calculator uses one-half × base × perpendicular height × thickness; it does not use a sloped side as the perpendicular height.
Calculating concrete for Sonotubes and circular forms
Select the Sonotube or round-column shape, choose a common form diameter in inches or select Custom, then enter the filled height and number of identical tubes. A solid circular form uses π × radius² × height. Do not use hollow-tube mode unless there is a real unfilled center.
Bagged concrete versus ready mix
Bag count uses the selected nominal yield and always rounds up. Actual yield can vary with mixing water, consolidation and product. Ready-mix truckloads are calculated from ordered cubic yards and the entered truck capacity.
Concrete calculator questions
Do I need extra concrete?
Most jobs use an overage because excavation and form dimensions are rarely exact. Select a project-appropriate percentage rather than relying on a fixed hidden assumption.
How are concrete steps calculated?
The tool treats a solid staircase as stacked rectangular steps: width × rise × run × n(n+1)/2.
Is square yardage the same as cubic yardage?
No. Square yards measure area. Concrete is ordered by cubic yards, which include thickness or height.