Concrete Calculator
Volume for any pour — slabs, footings, walls and columns, added up.
Element
= 192" (16')
= 144" (12')
= 4"
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Concrete · Result
CalculatedORDER (INCL. 10% WASTE)
2.75 cubic yards to order, including 10 percent waste
- Net volume
- 2.37 yd³
- With waste
- 2.61 yd³
- Waste
- 10%
- Order step
- 0.25 yd³
Waste allowance 10%
SUGGESTED DEFAULTChangeOutput unit defaulted to cubic yards because at least one dimension was entered in imperial units
SUGGESTED DEFAULTReady-mix order increment 0.25 yd³ and minimum 1 yd³ are UI defaults; suppliers differ
SUGGESTED DEFAULTBag counts use each product's printed approximate yield; cubic-metre yields are derived from the printed cubic-feet figures — see Methodology
MFR SPECCode references & assumptions · 3
How this result is supported
- SUGGESTED DEFAULTOutput unit defaulted to cubic yards because at least one dimension was entered in imperial units
- ASSUMPTION
- SUGGESTED DEFAULTReady-mix order increment 0.25 yd³ and minimum 1 yd³ are UI defaults; suppliers differ
- ASSUMPTION
- MFR SPECBag counts use each product's printed approximate yield; cubic-metre yields are derived from the printed cubic-feet figures — see Methodology
- PRIMARY-VERIFIED
What do these evidence labels mean?
- PRIMARY-VERIFIED
- directly supported by one authoritative primary source, quoted with section/page/figure
- CROSS-VERIFIED
- independently supported by two or more appropriate authoritative sources
- DERIVED
- mathematically derived from PRIMARY-VERIFIED values; the derivation is preserved in data and in code
- INTERPRETED
- a source exists but translating it into calculator behaviour required interpretation
- CONVENTION
- recognised trade practice, not a mandatory provision
- ASSUMPTION
- product/design assumption or useful default with no authoritative basis
- UNVERIFIED
- insufficient authoritative evidence
Code references and product data are quoted in the units their source uses.
Reference checks are informational, not compliance determinations.
How concrete is calculated
A pour is rarely one shape. Each element is entered on its own, converted to a common unit and summed, so a slab with two footings and a column is one order rather than three sums done by hand.
Waste is applied once to the total, then the order quantity rounds up to the supplier's increment — a quarter yard by default, which you can change because it is a supplier term rather than a fact. Both figures are shown: net is what the forms hold, order is what to buy.
The quarter-yard step and the minimum order are reported as assumptions rather than folded into the number, so a supplier with different terms is a change to an input, not a reason to distrust the result.
slab / footing: V = length × width × thickness
wall: V = length × height × thickness
round column: V = π × diameter² ÷ 4 × height
order = ceil(V × (1 + waste) ÷ 0.25) × 0.25
Ready-mix is sold in quarter-yard steps, so the order is rounded up to one.