Free with a MASK account
Ad Metrics Calculator
Work out CTR, CPC, CPM, CPA, ROAS and ROI from the numbers you already have.
Runs entirely in your browser — what you enter is never sent to MASK. Your account records that you used this tool, and nothing else about it.
Results
Six numbers, six formulas, no black box. Each result below shows the formula it used and the figures it put into that formula, so you can check any of them by hand.
On ROAS. Meta reports return on ad spend as a multiple — 5x. Google Ads states the same idea as a percentage, dividing $5 of value by $1 of spend to describe a 500% target ROAS. Neither is wrong, so both forms are printed side by side.
On ROI. This page computes ROI as (revenue − cost) ÷ cost × 100, and divides by whatever you put in the cost box. That convention matters: Google’s own worked example uses the cost of goods sold as the denominator, while much marketing writing uses ad spend alone. The same sale can therefore return two very different ROI figures depending on which cost is meant, which is why the box is labelled cost rather than being quietly assumed to be your ad spend.
There are no “good” or “bad” thresholds anywhere on this page. A CTR that is excellent in one auction is poor in another, and we have no sourced basis for telling you which is which.
Questions
- Is CTR a percentage or a decimal?
- A percentage. Google Ads gives the worked example directly: 5 clicks and 100 impressions is a CTR of 5%. This calculator multiplies by 100 for you, so 0.05 is never the answer you get here.
- Why is ROAS shown twice, as 4.0x and 400%?
- Because the two big platforms disagree on the unit. Meta reports return on ad spend as a plain multiple, and Google Ads states it as a percentage — Google's own example divides $5 by $1 and calls it a 500% target ROAS. It is one number in two dialects, so this tool prints both rather than picking a side and looking wrong to half its users.
- Which cost does the ROI figure divide by?
- The cost box on this page, and nothing else. There is no single agreed denominator: Google's worked ROI example uses the cost of goods sold, while a lot of marketing writing divides by ad spend alone. Those give materially different answers from the same sale, so decide which cost you mean before you type it, and read the result as ROI against that cost.
- Is ROI just ROAS minus one?
- Only in the narrow case where the cost is nothing but ad spend and the revenue is gross. As soon as the cost of goods sold, shipping or fees enter the cost figure, the two stop tracking each other, so this tool computes them separately from what you typed instead of deriving one from the other.
- Why does a metric show a dash?
- Because it cannot be computed honestly. Either a number it needs is missing, or the number it would divide by is zero. Dividing by zero impressions does not produce a very big CTR, it produces no CTR at all, so you get a dash and a sentence saying which box to fill rather than a made-up figure.
- Does anything I type here leave my browser?
- Your numbers do not. The calculator is a few lines of arithmetic running on the page, and no figure you type — spend, revenue, conversions — is ever sent to MASK. It does talk to MASK for two things, neither of which is a figure you typed: to check whether you are signed in, and to record on your account that you used this calculator. That record is the tool and the time, and this tool is allowed to attach no numbers to it at all. So closing the tab discards the figures, and what stays behind is a line on your account saying you did some arithmetic here.