What is a Conversion?

Conversion is the generic term used for an action or acquisition completed on a CPA campaign. Basically if you are trying to track something like how many sales an online ad has generated, a conversion is when the thing that you want to happen, happens.

The term comes from the idea of converting a potential customer into an actual customer. The word sale isn’t used, as a conversion can mean anything that an ad was trying to get a user to do (such as sign-up for an email list, purchase a product or download an app). There are words which specifically mean different types of conversion (in the previous examples: lead, sale, download), but conversion is the umbrella phrase used.

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Technical Information

You often need a Conversion Pixel in place to track conversions, which can often be a bit fiddly as they require putting code directly on to a site’s confirmation page to work.

To track how many conversions an ad has generated isn’t as simple as seeing how many people clicked on an ad and then immediately made a purchase. This would be unfair to the publisher hosting the ad, as many people are convinced by ads to make conversions, but do not in fact make the purchase at that exact moment.

This is why Post-Impression and Post-Click Windows are usually agreed between the publisher and advertiser. These mean the amount of time after an ad is seen or clicked on (respectively) that an ad still counts as having made that conversion.

Of course many users will see an ad multiple times on multiple sites before making a purchase, and it wouldn’t be fair on the advertiser to have to pay multiple times for a single conversion. The rule of thumb is that the last website an ad was clicked on or seen usually gets paid for the conversion.

Therefore advertisers usually get the finally say on how many conversions a publisher has actually made, by putting the data from where all conversions have come from through a process called de-duplication.

Publishers can try and increase the amount of conversions their site(s) generate by optimising towards Conversion Rate, however this is often quite a fraught process, due to the nature of CPA campaigns.


Other names for Conversion (synonyms)

Acquisition, Action


Not to be confused with




Conversion Definition


Find out more

Conversion Rate

Conversion Rate Calculator

Conversion Tracking

CPA Calculator

CPA Definition

Buying Ads on a CPA Basis

Selling Ads on a CPA Basis

Author: Justin Driskill

Justin is the founder of The Online Advertising Guide and a freelance Digital Projects Manager.

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