How We Source Our Numbers

Policy last updated:

A calculator that gives you the wrong number costs real time and money, whatever it's calculating: an under-ordered patio base, ad spend planned around the wrong CPM, a seeding rate doubled by mistake. So it matters where the numbers come from. This page states the rule every tool on this site follows, and who is answerable for it.

Who builds these

Every calculator on this site is built and checked by the Bunny Corner team. No figure is invented, no formula ships unchecked, and no page carries a byline more specific than that — the team, not one individual, is accountable for what's published.

This is published reference data applied with care, not original research, and not a substitute for a licensed professional or a platform's own reporting on a decision where getting it wrong carries real consequences. Where a calculation approaches that line, the tool says so.

Where the numbers come from

The rules on this page apply everywhere. The sources themselves are specific to what a calculator covers, so they're grouped by category below — each ordered by preference, with a lower tier used only when nothing higher publishes a figure.

Landscaping

Retaining walls, drainage, grading and material take-offs draw on published civil and horticultural references, not on other calculators.

  1. University extension services

    State cooperative extension programmes: Penn State, Oregon State, Texas A&M AgriLife and their peers. Regionally specific and peer-reviewed. Default first stop for seeding rates, soil amendment quantities and plant spacing.

  2. Federal agencies

    USDA and the Natural Resources Conservation Service for soil classification, plant hardiness and conservation practice standards. NOAA and the National Weather Service for frost dates, rainfall and evapotranspiration.

  3. Published material specifications

    Manufacturer technical data sheets and product labels for figures that are properties of a specific product: aggregate densities, block dimensions, emitter flow rates, coverage rates printed on the bag.

  4. Industry standards bodies

    ASTM, the Interlocking Concrete Pavement Institute, the Irrigation Association and equivalents, for installation tolerances and design conventions that no public agency publishes.

Marketing

Ad-spend and performance metrics (CPM, ROAS, CTR, CPC) draw on the platforms that actually report them, not on secondary blog posts repeating a number.

  1. Platform documentation

    Official help centres and documentation from Google Ads, Meta Ads Manager, LinkedIn Campaign Manager and equivalents, for how a metric is defined and calculated on that platform.

  2. Measurement standards bodies

    The IAB and the Media Rating Council, for viewability and impression-counting standards that apply across platforms.

  3. Published benchmark reports

    Industry benchmark reports from recognised publishers, used only for reference ranges — never treated as a substitute for a platform’s own definition of its metric.

Generators

This niche is for inspiration and novelty, not a factual claim. It generates prompts and ideas, not measured figures, so the sourcing rules above don’t apply to it — there is nothing here to trace to a source.

How a figure is accepted

Every published number traces to a source

If a figure appears in a calculator, a reference table or a worked example, it came from one of the tiers above. Sources are listed on the page itself, not buried in a site-wide disclaimer.

Formulas are confirmed against two independent sources

Before a calculator ships, its underlying formula is checked against at least two sources that do not cite each other. Where they disagree, the page says so and explains which convention it follows.

Ranges are reported as ranges

Real materials vary. Gravel density depends on the stone; seeding rates depend on the cultivar and the season. Where a source gives a range, the calculator carries the range through rather than collapsing it to a false single number.

Regional and platform figures are labelled as such

Frost dates and watering rates are not universal; a CPM benchmark on one ad platform does not hold on another. Where a number only holds for a particular climate, market or platform, the page states which.

What we do not do

  • We do not copy figures from competing calculators. If another site is the only place a number appears, that is a reason to distrust it, not to repeat it.
  • We do not generate numbers with a language model. AI assists with drafting prose; it is not a source of engineering data, and no figure enters a calculator on its authority.
  • We do not invent precision. A number sourced as "roughly 2,800 lb per cubic yard" is not republished as 2,835.
  • We do not treat marketing copy as a specification. A product page claim is used only when it also appears on the technical data sheet or the label.

Reviews and corrections

Every tool page carries a last updated date. That date reflects the last time the page's figures and sources were checked against their originals, not a cosmetic edit.

Going forward, each tool is reviewed at least annually, and sooner when a source publishes revised guidance or when a reader reports a problem. Seasonal tools (frost dates, seeding windows) are reviewed ahead of the season they apply to. This is the commitment the site is run on; pages record their own history through the dates they carry.

If you think a number here is wrong, please tell us. Emailcontact@bunnycorner.com with the tool and the figure in question, and a source if you have one. Corrections to a published number are made on the page, and the page's updated date moves with them.