Editorial Policy

MakeCalcs is a calculator site, and accuracy is the product. This page explains how we build, verify, and maintain the tools and content on this site. It is written for users who want to understand the rigour behind the numbers, and for anyone evaluating whether our results can be trusted.

Formula sourcing

Every calculator formula is sourced from a verifiable reference. We prioritise, in order:

• British Standards — BS 5385 for wall and floor tiling, BS 8000 for workmanship, BS 3882 for topsoil grades, and other relevant standards
• Manufacturer specifications — coverage rates, mixing ratios, and application thicknesses from product datasheets
• Industry guidelines — published guidance from trade bodies and professional organisations

Each calculator page cites its formula source. Where multiple sources exist, we cross-reference and note any discrepancies. We do not invent values for waste percentages, coverage rates, or material densities.

Waste factors

Waste percentages are not arbitrary. They come from documented industry practice:

• Straight tile layout: 10% (BS 5385)
• Brick bond tile: 12%
• Diagonal tile: 15%
• Herringbone tile: 18%
• Laminate and hardwood flooring: 10% standard, 15% diagonal
• Wallpaper: calculated from pattern repeat formula, not a flat percentage

When a calculator auto-sets a waste factor based on pattern selection, the source rate is shown. Users can override this value if their project requires a different allowance.

Testing methodology

Every calculator undergoes two levels of testing before publication:

• Primary test: all inputs populated with a standard scenario. Every output value is verified against manual calculation using the cited formula.
• Variant test: an edge case or alternate scenario — for example, an L-shaped room, a diagonal laying pattern, or imperial units — to confirm the calculator handles non-standard inputs correctly.

Worked examples on each calculator page are verified against the calculation engine. The numbers in the narrative match the actual output. If they do not, the calculator does not publish.

Our calculators are independently reviewed by Glen Todd, a construction professional with 25+ years' experience, and Asst. Prof. Bojan Žugec, PhD, an academic mathematician at the Faculty of Organization and Informatics, University of Zagreb. Per-page reviewer assignment is by topic fit. Glen covers the 12 interior calculators and 4 construction-adjacent garden calculators within his trade scope. Bojan covers the mathematical correctness of all 22 calculators and is the primary domain reviewer for the 6 horticulture garden calculators pending engagement of a topic-matched horticulture specialist — see the reviewers page for the open seat and credential profile.

In concrete terms: every calculator has a minimum of two automated tests — one covering a standard scenario with all inputs populated, and one covering an edge case such as an L-shaped room or imperial units. Worked example values are verified programmatically against the calculate() function output, so the numbers in the narrative are confirmed results, not rounded estimates. Source links cited on each calculator page are periodically checked for availability.

Cost data

Where calculators include cost estimates, these are expressed as ranges (never single values) sourced from at least two UK retailers. Cost data includes a verification date and an expiry date set six months later. When cost data expires, the calculator is flagged for review.

Content review cycle

Every content page has three date fields that drive our review process:

• Last updated: when the content was last meaningfully changed (visible on the page and in search engine metadata)
• Content review date: when the content was last checked for accuracy, even if no changes were needed
• Cost data expiry: six months from the last cost verification (triggers a review when reached)

Content standards

Educational content on each calculator page is written to help you understand the calculation, not to pad word count. Each page includes:

• An explanation of how the calculation works and what inputs affect the result
• At least two worked examples with real-world scenarios, showing inputs, maths, results, and a practical takeaway
• A glossary defining technical terms used on the page
• Frequently asked questions with substantive answers (not one-liners)

Independence

MakeCalcs does not have commercial relationships with material manufacturers or retailers. Calculator results are not influenced by brand partnerships. When we reference products or brands, it is for illustrative purposes or because their datasheets are publicly available sources.

Corrections

If you find an error in a calculation, formula source, or educational content, please report it via the contact form. We investigate every report and correct confirmed errors promptly. Significant corrections are noted in the page's update history.

About the author

MakeCalcs is built and maintained by Danijel (Dan) Dadovic, a Commercial Director at Ezoic with over eight years in digital publishing, and a PhD candidate in Information Sciences at the University of Zagreb. Dan holds a Master of Informatics in Business System Organisation and a Master of Economics — a background in information systems and data accuracy that directly shapes the methodology described on this page.

This methodology is not new to MakeCalcs. Dan has applied the same approach — formula sourcing from authoritative references, known-value testing, and multi-material output — across a portfolio of six calculator sites including PrinterTools, VoltCalcs, HardHatCalc, and BinBosh— all part of the CalculatorCorp portfolio. The process has been refined across multiple projects over several years. More about the person behind the site is on the about page.