Concrete

Concrete step volume

A step profile is not one large bounding box unless it is truly solid to those dimensions. The transparent method is to sketch non-overlapping rectangles so every volume is counted once.

First answer

Model each solid rectangular portion as length × width × height, add the portions without overlap, divide by the selected bag yield, and round up.

Run the calculator

Formula or decision rule

sum of non-overlapping rectangular volumes × allowance factor ÷ selected bag yield

Use finished concrete dimensions, not the outside of unrelated form bracing.
Avoid double-counting where rectangles overlap.
The product is specified for placements at least 2 inches (50 mm) thick.

Step decomposition check

Step decomposition check
Part	Volume	Check
Lower block	length × width × height	count once
Upper block	length × width × height	exclude overlap
Total	sum of blocks	same unit
Bags	total ÷ stated yield	round up

Work through the project

Draw a side profile
Label rise, run, width, and the actual solid portions before entering any volume.
Separate the blocks
Choose a set of rectangles that fills the profile without gaps or overlap and calculate each one.
Review the construction plan
Formwork, reinforcement, substrate, bonding, curing, and code are outside the quantity result.

Safety and scope

Steps are life-safety walking surfaces; verify geometry and applicable requirements.
Follow concrete product handling and curing instructions.

Sources and scope

Source links reviewed July 16, 2026. A review date is not the document's publication date.

QUIKRETE: Concrete Mix No. 1101 Technical Data SheetNorth America · manufacturer data sheet
Bag counts are based on stated approximate yield and must be rounded up to whole bags.
National Institute of Standards and Technology: NIST Guide to the SI, Appendix B — Conversion FactorsUnited States · government standard
Code retains exact defining constants where NIST identifies an exact relationship.