A supplier increment is optional and comes from you. It changes only the rounded order line, never the underlying calculated quantity.
Cubic-yard conversion and supplier rounding
Calculated yd³ = order ft³ ÷ 27; rounded yd³ = ceil(calculated yd³ ÷ increment) × increment
One cubic yard contains 27 cubic feet. The first result is the calculated waste-adjusted quantity before any supplier purchase-unit rule.
When an increment is present, the tool rounds upward to that increment. It does not infer a minimum order, truck size, or delivery policy.
Worked example: preserve all three yard values
The 10 ft × 12 ft × 4 in slab is 40.00 ft³ exact, or 1.48 yd³. With 10% waste it becomes 44.00 ft³, or 1.6296 yd³ calculated.
If you enter a 0.25 yd³ supplier increment, ceil(1.6296 ÷ 0.25) × 0.25 = 1.75 yd³. The page continues to show 1.48 exact, 1.63 calculated, and 1.75 supplier-rounded instead of replacing one with another.
Assumptions you control
The conversion uses exactly 27 ft³ per yd³. Concrete waste begins at 10% and remains editable. Supplier increment is blank until you enter one.
An increment is stored as a local project assumption and should match information from the supplier you intend to contact.
Use local supplier information
Ask a supplier which increment applies, then enter it exactly. If no increment is entered, the unrounded calculated order quantity remains the final yard result.
No delivery model
This mode does not choose an increment or model plant minimums, short-load charges, delivery, truck capacity, returns, scheduling, tax, equipment, or labor.
It does not recommend bags or ready-mix. It only keeps the volume conversion and optional rounding reproducible.
Sources and review dates
- Concrete Cal calculation method v1.0 · Reviewed 2026-07-11 · Planning method
- QUIKRETE concrete quantity calculator · Reviewed 2026-07-11 · Official source