How we build and check our calculators
A useful estimate needs a formula, suitable inputs and an explanation of its limits. Here is how to read our calculations, what our software checks cover and which decisions still depend on your product and project.
The short version
Each calculator publishes a formula and worked example. The software has automated checks for default inputs, selected examples and calculation behaviour. Coverage presets, densities and allowances remain estimating assumptions unless tied to the exact product you will use.
Separate the formula from the inputs
Three different kinds of information can appear in an estimate. They do not provide the same kind of assurance:
- Geometry and arithmetic. Area, volume, unit conversion and whole-pack rounding can be derived directly. For example, a rectangle 4 m by 3 m has an area of 12 m².
- Product information. Coverage, yield, permitted thickness and pack size belong to a particular product. Use its current label or data sheet, for the market where you buy it. A linked example is not a specification for every brand.
- Planning assumptions. Waste percentages, typical opening sizes and generic bulk densities are starting points. Compare them with your measurements, layout and supplier information.
Read presets as assumptions
A preset lets you try a calculation before you have selected a product. It does not mean that manufacturers have certified this estimate. The page explains its working, and reference links help you check relevant product information.
Where an input is editable, replace the default with your own figure. Where a tool offers only presets or a fixed conversion, compare its displayed formula with the product specification before ordering. A lower paint coverage rate increases the quantity; a different bag yield changes the bag count.
| Input or rule | Example on the site | How to check it |
|---|---|---|
| Paint opening deduction | 1.9 m² for each selected door | Measure the actual opening; use net-area mode when the default does not fit |
| Flooring pack coverage | 2.22 m² in the laminate default | Read the coverage on the exact pack; other products use other sizes |
| Cutting allowance | 8% in the straight-layout laminate example | Check board arrangement, cuts and product instructions |
| Concrete and mortar batching factors | Generic dry-volume and bulk-density assumptions | Confirm the mix design and yield with the supplier; these are not strength specifications |
| Wallpaper trim | 100 mm added to each drop before repeat rounding | Check wall heights, pattern matching and the wallpaper instructions |
What the automated checks cover
Our verification suite runs every calculator with its default inputs and checks for a valid result and required page information. Selected examples also assert expected quantities. Additional checks exercise unit conversions, material-pack coverage and the calculation code as it is prepared for the browser.
The verification command runs calculation tests, builds the static pages and validates their structure and links. A standalone page build is not itself a calculation test. Written examples and product references also need editorial review; passing software tests does not prove every sentence, every product or every possible input combination.
Automated tests help detect regressions in the cases they cover. They do not measure your room, test the materials or certify that the estimate meets building requirements.
Corrections and updates
- Reproducible reports. Include the calculator, units, input values, expected result and source of that expectation. This lets us distinguish a calculation problem from a different product assumption.
- Update dates. A changed content date identifies an update to the page. It is not a claim that a manufacturer has reviewed or approved it.
- Reader reports. Anyone can report a problem at contact@orderenough.com. We aim to respond within five working days.
What we deliberately do not do
- We distinguish allowance from rounding. Check the selected waste allowance separately from the extra quantity caused by buying whole packs. Some tools also use fixed planning assumptions explained on the page.
- We keep calculations independent of product links. Optional equipment suggestions never alter the formula or the amount of material calculated. Check the product specification against your own project.
- We do not gate results. No email address, no account, no "enter your postcode for a quote".
Independence and advertising
The site is set up to support Google AdSense. Display ad spaces, where enabled, are labelled and kept separate from calculator controls and results. Advertising does not change the formulas or quantities.
Some calculator pages also contain labelled Amazon affiliate links. We may earn commission from qualifying purchases. We check the listed product identity and describe its possible role in the job; we do not claim to have tested the equipment ourselves. The selection is not a price comparison or an exhaustive product review. See how the site is funded.
Limitations you should know about
Material calculators are estimates. They assume your measurements are accurate, your surfaces are typical, and the product performs as its data sheet claims. Real jobs have out-of-square rooms, absorbent patches and mixed substrates.
Treat our output as a well-founded starting point for an order, not as a guarantee. For anything structural, or where a mistake would be expensive or unsafe, get professional advice. Our terms set this out formally.