1. Measure — break the job into measurable parts
A driveway is not one number and a fence is not one rectangle. Each calculator asks for the parts you can actually measure on site: lengths, widths, depths, spacing, gate counts. Areas can be summed rather than forced into a single shape, so irregular projects stay honest.
Units are labelled on every field, and defaults are planning defaults (post spacing, joint width, layer depths) rather than arbitrary starting values — the same defaults the assumptions table shows.
2. Calculate — the form hands off to the engine
When you press Calculate, the page converts your form state into a typed engine input and calls one function. No arithmetic happens in the interface layer, and no formula is written twice — the engine under src/lib/calculations is the only place a calculation exists.
That is why the same number appears everywhere: the calculator page, the worked example in a guide and a line in Project Mode are all produced by the identical call.
3. Plan — results become one project
Any result can be added to Project Mode. The calculation arrives as a material line that keeps its inputs, its result values, its form state, the calculator it came from and the assumptions that were used — so months later the line can still explain itself.
From there the project grows into areas, quantities, costs from prices you enter, extra hand-written lines, a shopping list with checkboxes and a printable plan.
4. Verify — before anything is ordered
Estimates are planning aids. Before purchase or construction, confirm supplier packaging and yields, product density, site conditions, local requirements and manufacturer instructions. The site states this on every calculator and every guide, because the last mile of a project cannot be calculated from a browser.
5. One engine, one meaning per number
Because every calculator dispatches through the same engine, shared concepts have one definition: "waste", "compaction" and "tons" mean the same thing on the gravel page and the driveway page. The engine-bridge layer only adds presentation summaries on top of typed results — it never recomputes them.
The engine is covered by unit tests that assert quantity behaviour (spacing, rounding, waste interaction) rather than snapshots, so a formula cannot change silently.
6. Validation before arithmetic
Engine inputs are validated at the boundary: empty, negative or nonsensical values produce a named error instead of a plausible-looking wrong number. The interface shows those errors next to the field that caused them — you are told which input rejected the calculation, not given a NaN.
7. Assumptions are data, not prose
Waste percentages, densities, bag sizes, compaction factors, joint widths and rounding steps live in one centralized assumptions file shared by every calculator. The methodology page renders that file as a reference table, and every calculator shows the assumptions that applied to your result.
Where a number matters to your project — waste, density, compaction — the calculator lets you override it rather than forcing a default on you.
8. Results carry their provenance
Each result shows the inputs it was calculated from and the headline outputs that matter for ordering. When something cannot be derived from what you entered (for example, edge restraint without a perimeter), the result says so instead of inventing a figure.
Guide pages work the same way: every worked example states its inputs and is generated by calling the engine, so a guide and a calculator can never disagree about the same measurement.
9. Your prices only — no invented costs
The site does not publish current market prices, because it has no live feed of them. Cost fields use the prices you enter; a missing price is shown as "Price not entered" and excluded from the total rather than filled with a guess. A cost total is only ever as current as the numbers you gave it.
Cost calculations use the prices you enter. MeasureToBuild does not claim to know your local current market price.
10. Your project stays in your browser
Project Mode persists to your browser's local storage — no account, no server, no sync. Project Mode data is not transmitted to a MeasureToBuild server, and printing the plan works entirely on your machine. Clearing the project deletes the data, because there is no copy anywhere else. The privacy page spells out exactly what is stored.
11. Guides are built from the same material
The guide library — project, material and cost guides — is content data rendered through one accessible template. Its worked examples call the engine, its claims link to their sources where a claim is checkable, and every guide ends with what it cannot tell you. No page is given authority it has not earned: no fake bylines, no review scores, no invented statistics.
12. What the site will not do
It will not tell you a structure is safe, that a permit is not required, that a supplier will accept an order quantity, or what your project will cost at today's prices. Those decisions involve local code, site conditions and market information that a calculator cannot see. The site does the arithmetic honestly and tells you where its knowledge stops — then the methodology page and about page document both in full.