Methodology

The formulas are standard, and they're shown to you

Every calculator here uses the conventional definition of its metric — the one you'd find in a finance textbook or a platform's own help docs. Nothing is proprietary and nothing is hidden.

That's why each page prints the formula and defines every variable in it. If you disagree with how a metric is defined, you can see exactly what we did and rebuild it your own way in a spreadsheet. A calculator that won't show its math is asking for trust it hasn't earned.

Worked examples are checked numerically

Each page includes a worked example with real numbers. Those examples are computed and verified against the same function that powers the live calculator, so the walkthrough and the tool can't drift apart.

If an example ever disagrees with the result you get from entering the same inputs, that's a bug — treat the live calculator as authoritative and let us know.

Benchmarks are directional, not authoritative

The benchmark tables are compiled ranges reflecting commonly reported figures for each business type. They exist to answer “is my number roughly normal?”, not to certify a target.

Some of these figures move fast — ad platform CPMs, channel conversion rates, and email engagement in particular. Anything you're going to plan a budget around should be checked against your own historical data first, and against a current primary source second. Your own last twelve months beat any industry average.

Gauge thresholds (the healthy / borderline / risky bands) follow the same logic. They're a reading aid, not a verdict.

Some calculators are explicitly simplified models

A few metrics have no single agreed formula — the value of a backlink, the CPC impact of a Quality Score change, and diminishing returns across a marketing mix are the clearest examples. Where that's the case, the calculator says so on its own page rather than implying a precision that doesn't exist.

Use those as structured thinking tools: they'll tell you the direction and rough magnitude of a change, and they will not tell you what will happen next quarter.

What this is not

None of this is financial, investment, tax, or legal advice. These are arithmetic tools for marketing planning. Decisions with real money behind them deserve your own data and, past a certain size, a professional who is accountable for the answer.

Privacy: nothing you type leaves your browser

Every calculation runs client-side in JavaScript. Your inputs are never sent to a server, never stored, and never logged. There is no account, no email gate, and no “unlock your result” step — the answer appears as you type.

Corrections

If a formula, benchmark, or example here is wrong, it should be fixed rather than defended. Report it and it gets corrected on the page.