The only way an advertiser knows for sure whether clicks or impressions gives the best return on the advertising spend is by trialing the same ad on both systems.
Impression-based advertising displays a set number of impressions, or placements in a given time. Bidding 50 cents for an impression-based advertising campaign means paying 50 cents for 1,000 impressions. Any clicks you get are free. When all the impressions are delivered, the advertising stops.
Clickthru advertising guarantees that the only time you pay for advertising is when a user clicks your ad. Bidding 50 cents per click, means you are charged 50 cents every time someone clicks your ad—regardless of whether it is the first impression for your ad or the millionth. This is the advertisers favourite way to make sure the required number of prospects hit your marketing pages in a given time.
Sometimes, you can get the same marketing result for less money by opting for one payment method over the other.
If you want 50 clicks per day, but that costs 50 cents for each click, you have to spend $25 per day. You may find that you can get roughly 50 clicks per day by budgeting $15 for 30,000 impressions a day.
The same goes for impressions. You may want 30,000 impressions, but the cheapest way to do it may be by bidding 50 cents each for clicks.
To find out, you need to know how many clicks you get per 1,000 impressions by trailing the ad and then tweaking the delivery system to get the best deal.
You need to have web analytics set up on your landing page picking up your Facebook ad click thrus to work this out.