How to use the ad metrics calculator
- Choose the metric to solve: CPM, CPC, CTR, CPA, ROAS or conversion rate. Choose All metrics to see every one your numbers allow.
- Enter only the numbers the metric needs. The form shows the fields for your choice, and the instructions name anything missing.
- Read the result and the formula with your numbers filled in.
- If a number you need is zero or would make the ratio meaningless, the tool tells you instead of showing a result.
Formula
CPM = ad cost / impressions x 1,000
CPC = ad cost / clicks
CTR = clicks / impressions x 100
CPA = ad cost / conversions
ROAS = revenue / ad cost
Conversion rate = conversions / clicks x 100
ROAS is a ratio. A ROAS of 4.00x means each dollar of ad cost brought in four dollars of revenue, before any other costs.
Worked examples
CPC: $125 of ad cost and 250 clicks gives $125 / 250 = $0.50 per click.
CPM: $500 over 200,000 impressions is $500 / 200,000 x 1,000 = $2.50 per thousand impressions.
CTR: 250 clicks from 10,000 impressions is 250 / 10,000 x 100 = 2.50%.
CPA and conversion rate: 5 conversions on $125 of cost is $25.00 per conversion, and 5 conversions from 250 clicks is a 2.00% conversion rate.
ROAS: $500 of revenue on $125 of ad cost is 4.00x, which is $375 of revenue above the ad cost.
How the metrics connect
The metrics describe different steps of the same path: impressions turn into clicks (CTR), clicks turn into conversions (conversion rate) and conversions bring in revenue. CPM is the price of attention, CPC is the price of a visit and CPA is the price of a result. ROAS compares what you earn with what you spend.
They are linked by simple arithmetic. CPA equals CPC divided by the conversion rate: with a CPC of $0.50 and a 2% conversion rate, CPA is $0.50 / 0.02 = $25. That is why a small change in conversion rate moves your cost per acquisition so much.
Zero and impossible inputs
Every ratio divides by something. With no clicks there is no CPC, with no impressions there is no CPM or CTR, and with no conversions there is no CPA. The tool says which number must be above zero rather than showing infinity or a blank.
It also checks that clicks are not higher than impressions for CTR, and that conversions are not higher than clicks for a conversion rate. Some platforms count conversions that are not tied to a click. If your report does, calculate that figure against a different base.
Reading the results with care
Compare numbers from the same report, with the same date range and attribution settings. ROAS uses revenue, not profit, so a ROAS above 1.00x does not mean a campaign made money after product cost, fees and other expenses. For that, see the profit margin calculator and the break-even calculator.
Assumptions and limits
- The numbers you enter come from one ad report and one date range.
- Impressions and clicks are whole numbers. Conversions and money values may have decimals.
- ROAS uses revenue, not profit, and does not include costs other than the ad cost you enter.
- Percentages are rounded to two decimal places and money to four decimals for small per-unit costs.
Frequently asked questions
What is the difference between CPC and CPM?
CPC is the cost for each click, and CPM is the cost for every 1,000 times the ad is shown. CPC suits goals about visits, while CPM is common when the goal is reach or awareness.
What is a good CTR?
It depends on the platform, the format and the audience, so there is no single benchmark. Compare your CTR with your own earlier campaigns before comparing it with anyone else's.
How do I calculate ROAS?
Divide the revenue attributed to the ads by the ad cost. $500 of revenue on $125 of spend is a ROAS of 4.00x, or 400%.
Why does the tool refuse when clicks are zero?
Cost per click divides by clicks, and dividing by zero has no answer. Enter at least one click, or choose a metric that does not need clicks.
Can conversions be higher than clicks?
Sometimes, for example when one click leads to several purchases or when views count as conversions. For a conversion rate per click that is not meaningful, so the tool asks you to check the numbers.