Calculation Methodology

Every tool starts with a geometric, coverage, layout or cost model stated on its page. You supply the dimensions and the product-specific values. Worked examples use illustrative inputs and do not assert that every product has the same yield or coverage.

Units and conversions

Calculations use a consistent base system internally. One foot equals 0.3048 metres, one inch equals 25.4 millimetres, one square foot equals 0.09290304 square metres and one cubic foot equals 0.028316846592 cubic metres. One US liquid gallon equals 3.785411784 litres. Gallons in these tools are US gallons. One pound equals 0.45359237 kilograms.

Switching the display converts supported dimensioned inputs and results rather than changing the physical project. Some product ratios, densities or specialized dimensions retain the explicit units printed on their fields. Calculation breakdown notes may show the base units used in the formula. Prices remain in USD; this website does not fetch live currency exchange rates.

Waste, allowance and package rounding

When a tool applies a percentage allowance, it multiplies the applicable net quantity by one plus that percentage divided by 100. It then rounds up complete bags, rolls, sheets, boxes or stock lengths where appropriate. A continuous area estimate and a rectangular layout calculation answer different questions: dividing total area cannot guarantee that every offcut will fit.

Waste and contingency are separate. Material waste covers cutting, breakage or layout losses. Financial contingency covers uncertain project costs. Read the relevant tool to see which quantity receives an allowance; adding both to the same number without understanding the basis can double count costs.

Layout assumptions

Grid, strip, post and board calculations make the layout assumptions described on the tool page. Complex corners, mixed stock lengths, patterned installations and site-specific details may need a drawn cut plan. A stock-length calculation does not perform a structural design check.

Validation and results

Fields reject missing values, values outside their defined bounds and nonfinite results. Tools also check relationships such as deductions that exceed gross area. Displayed results are rounded for readability; the underlying calculation uses greater numerical precision. A rounded number is not a guarantee of measurement accuracy.

Product specifications take priority

Use the stated coverage, actual dimensions, compaction requirements and installation instructions from your chosen material. Moisture, surface porosity, pattern repeats, joint sizes and handling losses affect real quantities. Obtain appropriate professional advice for structural work, regulated systems and conditions beyond a material takeoff.

Reproducing an estimate

Record the measurements, units, allowance and package size. The CSV export includes inputs, results and the formula. A share link stores measurements in the URL fragment; anyone with that link can read them. Do not include personal or sensitive project information.