Marketing analytics
CPM, CPC, CTR and CPA.
Enter spend, impressions, clicks and conversions to get every ad metric. Or enter a CPM, CTR and conversion rate to see the CPC and CPA they imply.
CPM = cost / impressions x 1,000. CTR = clicks / impressions. CPC = cost / clicks. CPA = cost / conversions. $500 on 100,000 impressions, 1,500 clicks and 45 conversions is a $5.00 CPM, 1.5% CTR, $0.33 CPC and $11.11 CPA.
Your numbers
Result
Worked example
Spend $500 for 100,000 impressions, 1,500 clicks and 45 conversions. CPM = 500 / 100,000 x 1,000 = $5.00. CTR = 1,500 / 100,000 = 1.5%. CPC = 500 / 1,500 = $0.3333. Conversion rate = 45 / 1,500 = 3%. CPA = 500 / 45 = $11.11. Converting instead: a $8 CPM at a 1.2% CTR means 12 clicks per 1,000 impressions, so CPC = 8 / 12 = $0.6667, and at a 3% conversion rate CPA = 0.6667 / 0.03 = $22.22.
How it works
CTR is clicks divided by impressions; Google gives 5 clicks on 100 impressions as 5%. Conversion rate is conversions divided by tracked interactions; Google gives 50 conversions from 1,000 interactions as 5%. This tool uses clicks as the interactions.
CPM is the cost per one thousand impressions (Google describes CPM bidding as paying per one thousand views). CPC is the cost per click (Google describes CPC bidding as paying for each click). CPA is total cost divided by conversions, the formula Shopify gives for cost per acquisition.
Converting between them is algebra. 1,000 impressions at a given CTR produce 10 x CTR% clicks, so CPC = CPM / (10 x CTR%). CPA = CPC / conversion rate. The results are effective averages for the inputs you give, not a forecast.
Leave fields blank to skip a metric. Spend with impressions gives CPM; spend with clicks gives CPC; clicks with impressions give CTR.
Sources and basis (opened 2026-10-08): Clickthrough rate (CTR): Definition - Google Ads Help; Conversion rate: Definition - Google Ads Help; Cost-per-thousand impressions (CPM): Definition - Google Ads Help; Cost-per-click (CPC): Definition - Google Ads Help; Cost Per Acquisition: What It Is and How To Calculate - Shopify. Everything else is arithmetic on your inputs.
Inputs are user-entered figures. Results are planning estimates, not financial advice or a forecast of future performance. Everything runs in your browser. Nothing you type is sent or stored.
FAQ
How do I convert CPM to CPC?
Divide the CPM by 10 times the click-through rate in percent. A $8 CPM at a 1.2% CTR is 8 / 12 = $0.67 per click.
How do I calculate CTR?
Divide clicks by impressions and multiply by 100. 5 clicks on 100 impressions is 5%.
How do I calculate CPA?
Divide total ad cost by the number of conversions. $500 and 45 conversions is $11.11 per conversion.
Why do my numbers differ from the ad platform?
Platforms may count clicks, interactions and conversions differently and apply attribution windows. Use the same period and the same definitions on both sides.