PROJECTCALC / OUR STANDARDS

Our calculation methodology

Every estimate should be explainable. ProjectCalc uses explicit measurements, published unit definitions and standard geometry. It does not hide guessed dimensions, market prices or design decisions behind a result.

1. Parse and validate the measurement

Empty entries, negative dimensions, zero divisors, unsupported formats and impossible geometry produce errors. Plain dimensions use the selected input unit. Explicit units override it: 4 in always means four inches, even when the input selector is set to meters.

Fractional entries such as 3/8 and 7 1/2 are evaluated before conversion. Compound feet-and-inches entries require the inches portion to be below 12. Lengths, counts and percentages have finite limits to reject impractical or unsafe numerical ranges.

2. Convert before calculating

Geometry is calculated in meters, square meters and cubic meters. We use the exact international foot definition of 0.3048 meters, with squared and cubed factors for area and volume. Mass conversion uses 0.45359237 kilograms per pound. See the NIST conversion tables.

3. Separate net quantity from purchase quantity

A measured volume is different from an order allowance. We show both. Waste is applied as net quantity × (1 + percentage ÷ 100), then whole bags or pieces are rounded upward. Fence bays and coverage pickets are counted per run before a purchasing allowance is applied. Post counts follow the layout without an automatic spare-post allowance.

4. Preserve precision

Calculations use full JavaScript numeric precision internally. Displayed values are rounded for readability. Whole-piece rounding includes a tiny floating-point tolerance so a result mathematically equal to 20 does not become 21 because of a machine-representation artifact.

5. State construction assumptions

Hole geometry assumes straight cylindrical walls and subtracts actual post displacement. Concrete estimates use uniform thickness. Gravel mass depends on the bulk density you enter. Our approximate concrete bag yields refer to the QUIKRETE Concrete Mix data sheet; other products can differ.

These tools estimate quantities. They do not select safe embedment depths, determine soil capacity, size structural members, verify codes or replace project drawings and supplier instructions.

6. Test and correct

Automated tests cover reference calculations, invalid inputs, fractions, conversions, zero values, extremes and purchase rounding. Worked examples let readers check the same arithmetic. When a correction is needed, we update the engine and add a regression case.

Report an issue with the tool name, exact inputs and your expected result. Explore the calculators to see the method applied.