marketingmathcalc

About Marketing Math Calc

Last updated by Marketing Math Calc, published by AUSSIE-AI LTD

Marketing Math Calc is a set of free calculators for the arithmetic of paid media and growth: CPM, CPC, CTR, conversion rate, CAC, ROAS, break-even ROAS, ROI, lifetime value, ad budgets and social engagement rate. It is for people who check these numbers in a spreadsheet every week and want a quick, trustworthy second opinion.

Who publishes it

The site is published by AUSSIE-AI LTD, a company registered in England and Wales (company number 17193460). The calculators, guides and tests are written in-house. No ad platform, agency or software vendor has paid for a mention, and none of the companies whose help pages we cite has any connection with the site.

Where the formulas come from

The metrics here are definitions, so the first job is to use the definition the platforms themselves publish. For each calculator we read the relevant help page or guide and match its wording and worked example:

  • CPM, CPC, CTR and conversion rate follow Google Ads Help, which also supplies the 5-clicks-from-100-impressions CTR example and the 50-conversions-from-1,000-interactions conversion example.
  • ROAS follows Google's Target ROAS page ($5 of sales from $1 of spend is 500%) and Amazon Ads' ACoS guide ($50 of spend earning $100 is a 50% ACoS and a ROAS of 2).
  • ROI offers Google Ads' own method, which divides profit by all costs, next to the marketing-cost version most teams use. Both give the figures in Google's worked example.
  • CAC follows Shopify's and HubSpot's definitions, including HubSpot's ($300,000 + $100,000) ÷ 500 = $800 example.
  • Lifetime value follows Shopify's formula and its $50 × 3 × 2 = $300 example. The subscription version uses the standard steady-churn result that average lifetime is 1 ÷ monthly churn, and says so on the page.
  • Engagement rate has no single owner, so the calculator offers the denominators described in Hootsuite's guide and labels every result with the one used.

Where definitions differ between platforms, the page says so instead of picking one quietly.

How every calculator is checked

  1. Exact arithmetic. Inputs are converted to whole-number fractions before any division, and rounding happens once, at display: money and percentages to two decimals, half away from zero; counts to whole numbers. A non-zero amount that would show as 0.00 is given to four decimals.
  2. Published examples. Every worked example above is a test case. If the platform's number and ours ever disagree, the release stops.
  3. Every direction. Each calculator that can solve for more than one figure is tested in every direction, along with zero, negative, blank, non-numeric, very large, comma-formatted and percent-versus-decimal inputs.
  4. A second implementation. A separate program, written independently in another language, recomputes hundreds of random cases and must match the site to the last displayed digit.
  5. In the browser. An automated browser types into every calculator on phone and desktop widths, in light and dark mode, and checks the results and error messages.

What we leave out

Benchmarks. You will not find "average CTR for Facebook" or "a good ROAS" here. Those numbers vary by platform, country, industry, audience and year, and many published averages do not say how they were measured. A plan built on someone else's average is weaker than one built on your own data. If we ever add a benchmark, it will name its source and date on the page.

Advice. The calculators do arithmetic on the numbers you give them. They do not know your attribution model, your returns or your fixed costs, and they are not financial advice.

Your data

The calculations run in your browser. Nothing you type is sent to us or stored, apart from the currency symbol you choose, which your browser remembers for next time. The privacy policy has the details, including how ads on the site use cookies.

Paying for the site

The site carries advertising, which pays for hosting and upkeep. Ads never change a formula or a result.

Corrections

If a number looks wrong, use the contact page with the figures you entered and what you expected. We check the case by hand, fix any error, add the case to the tests, and update the date on the page.

References