Methodology

Our claim is verifiable accuracy, so this page explains exactly how the numbers are produced and where they come from. Nothing here is a black box.

How a calculation is derived

Each calculator is a pure function: inputs in, a structured result out, with no hidden rounding and no server round-trip. Every constant it uses is stored as a typed sourced value, a figure paired with its unit and the named standard it comes from, so the same constant drives the math, the citation shown next to the result, and the sources table. Intermediate values are not rounded; we round only the figures we display. The functions are covered by unit tests that assert specific sourced results, so a change to a constant that would move an answer shows up as a failing test.

Which standard each tool draws on

• Grout volume comes from CMHA TEK 09-04A, Table 2 (grout volume per 100 ft² of wall by thickness and grout spacing), which already includes a field-waste allowance for cell grout.
• Block geometry, nominal and actual dimensions, cell and web counts, and minimum face-shell and web thicknesses, comes from CMHA CMU-TEC-001-23, which reproduces the ASTM C90 physical requirements.
• Bag yields come from the manufacturer datasheet (QUIKRETE Concrete Mix No. 1101) for each bag size.
• Grout consistency references ASTM C476 and TMS 602, which specify the high (8 to 11 in) slump grout needs to flow into cells and around reinforcement.

Why we report two figures, not one blended number

For block fill we show two independent results and never average them. The CMHA Table 2 figure is the ordering number: it is drawn from filled walls and includes waste. The C90 minimum-thickness geometry figure is computed from the block’s actual dimensions minus the thinnest face shells and webs the standard permits, which produces the largest cell cavity the standard allows. The two approach the same answer from opposite directions: pure geometry from below, field data from above. Kept separate, they cross-check each other, and a reader can see the spread. Blended into a single number, that check disappears and the provenance is lost. So we keep them apart and label each. See how the two figures compare for the worked detail.

How constants are versioned

Reference data lives in typed modules under version control, not in a database or a CMS. Each constant records its value, unit, source, and an optional note, and changing one is a code change with a full history. The sources page is generated at build time by walking those modules, so it can never fall out of step with what the calculators actually use. Where a figure is not yet confirmed against a primary source, it is flagged in the data rather than guessed, and it is not presented as verified.

What these tools do not cover

Our calculators estimate material quantities for preliminary planning. They are not design tools and do not address:

• Permit and construction drawings
• Lateral bracing
• Connection design
• Footing sizing
• Seismic and wind loads
• Concentrated loads
• Reinforcement sizing
• Multi-span analysis

Any of these requires a qualified designer working from your project’s specifics and local code. Use our figures to plan and to order material, then confirm the design with the appropriate professional.