The same metric matters differently depending on what you sell.
You buy traffic, ship product and live on margin. The question is always whether the order paid for itself.
No cart, no checkout. A form fill or a phone call is the conversion, and the close rate happens weeks later.
Acquisition is an investment that pays back over months. Retention decides whether it ever does.
You defend numbers in front of clients. These are the ones that survive being questioned.
Three things every page does that most calculator sites skip.
Every calculator prints the formula it uses as a code block before the result. You can check the arithmetic instead of trusting a black box, and you can copy it into a spreadsheet when you need it somewhere else.
See it on break-even ROAS →Where a range exists, it is on the page with the channels and segments it came from. They are orientation, not targets - a $2 CPM that reaches nobody costs more per outcome than a $30 CPM that does.
See CPM benchmarks →The section nobody else writes: what goes wrong with this metric in practice. Peeking at A/B tests, annualising churn by multiplying by twelve, pricing on markup while reporting margin. That is the part worth reading twice.
See the A/B test trap →What the media costs before anyone buys anything.
What it costs to turn attention into a name or a sale.
Whether the campaign made money, not just revenue.
The numbers underneath every media decision.
What a customer is worth, and how long you wait for it.
Every metric here is one link in the same chain. A problem shows up at one link and gets blamed on another.
If cost per click rose but CPM is flat, the creative stopped working. If CPM rose and CTR is flat, the auction got harder. If both look fine and CPA still climbed, the landing page or the offer moved. Reading the chain in order is faster than guessing at the end of it.
Almost every bad decision in paid media starts with a target that nobody derived. A ROAS goal picked because it sounded ambitious. A cost-per-lead cap borrowed from a case study. A budget set by what was left over.
Each of those numbers has a correct value and it comes from the same place: contribution margin. Break-even ROAS is one divided by contribution margin. Maximum CPA is order value multiplied by contribution margin. Maximum CAC is profit LTV divided by three. Work those out first and every target below them stops being a guess.
1. Margin. Work out contribution margin – gross margin minus shipping, payment processing, packaging and a returns allowance.
2. Break-even. Convert that margin into the ROAS and CPA you must beat.
3. LTV and payback. If customers buy more than once, find what one is worth over the relationship and how long the money is tied up.
4. Budget. Plan backwards from a conversion target and check the resulting CPA against step two.
5. Diagnostics. CPM, CPC, CTR and conversion rate tell you where a campaign is breaking once it is running.
Every calculator runs in your browser. No values are transmitted, nothing is logged, there is no account and no cookie banner because there is nothing to consent to. Bookmark a page and it works offline.
Every calculator runs entirely in your browser. There is no account, no email field, no export gate and no server that ever sees what you typed. Close the tab and the numbers are gone.
No email wall in front of a result, and no upsell to a paid tier that does the same arithmetic.
No analytics by default, which is also why there is no cookie banner asking for consent to something that is not happening.
Every formula is the standard industry definition, written out on the page so you can check it rather than trust it.
The ranges are orientation, not targets. They move by country, vertical and how narrow the audience is.