Project Toolbench

Publication method

How calculator estimates are built.

Each live tool is scoped around a specific user task, documented with formulas and sources, tested against normal and edge cases, and reviewed in the browser before release.

  1. 01

    Define the task and limits

    Inputs, outputs, units, purchase options, error conditions, and excluded advice are specified before implementation. Related wording does not automatically become a separate page.

  2. 02

    Register formulas and sources

    Exact conversions use authoritative standards where available. Variable material properties, such as density and local price, remain user-entered rather than becoming unsupported defaults.

  3. 03

    Build one calculation core

    The calculator, result details, worked example, and copied estimate follow the same formula and rounding rules. Calculations run in the browser for the current tool.

  4. 04

    Test expected and unusual inputs

    Tests cover normal shapes, unit conversions, multiple areas, final purchase rounding, omitted optional fields, zero or negative values, unusual depth, large projects, and small results.

  5. 05

    Review the rendered page

    Desktop and mobile layouts, keyboard focus, error messages, resource loading, canonical URLs, links, printing, and public HTTP behavior are checked before a release is recorded.

Current calculator review basis

All three calculators use exact international length and volume conversions documented by NIST. Topsoil and gravel density remain supplier properties entered by the user. The concrete tool also requires package yield from a label or manufacturer data sheet instead of assigning one universal bag yield. The gravel tool does not hard-code a ton-per-yard conversion because rock type, grading, moisture, and supplier basis vary.

Formula review date: 2026-09-01