BookBub has widened its advertising platform for authors and publishers to cover cost-per-click (CPC) as well as cost per impressions (CPM) which was the sole choice originally.
It has launched a beta version of the CPC bidding option for any campaign and says this should enable authors to control their return on investment more easily.
At present, the BookBub CPC option is saying that other partners are on average bidding $0.30-$1.00 per click while on the CPM (cost per 1,000 impressions) the average bid is $7.29-$12.15 (which seems high to me).
Goodreads has an advertising programme for authors which charges a flat rate of $0.50 per click.
Should you choose CPC or CPM and what would be the effect on your ROI (return on investment)? This example puts your BookBub bid around halfway in the average bidding shown above.
We’ll say you’ll be paying $0.50 per click on a CPC ad and have a budget of $250, which means you will get a guaranteed 500 clicks.
If you pay $10 on a CPM basis for the same ad, also with a $250 budget, then your ad will be shown 25,000 times.
To get the 500 clicks that you’re guaranteed to get with the CPC model you would need a click-through rate of 2%, which is a relatively high CTR as click-through rates generally can range from well below 1% to 5%, which is considered an excellent CTR.
If you managed to run an ad with a lower CPM cost, such as $7.50 on a $250 budget then you’d get 33,333 impressions, so to get those 500 clicks you’d need a CTR of 1.5%, which is better but still not a sure thing.
You’d need a $5 CPM cost to get 50,000 impressions which would mean a 1% CTR would produce 500 clicks.
Some reports from independent authors say their experience is that CTR rates for BookBub CPM ads have been around 0.5%. One of the problems with BookBub ads is that they appear at the bottom of the emails which detail book offers, so opening the email counts as an impression but doesn’t guarantee that the ad is seen.
There is, of course, also the matter of whether those clicks using either CPC or CPM actually produce any real revenue in terms of sales.
Then there’s the fact that if you do opt for CPC at a low bid your ad might well be shown to very few people as when a reader opens an email, BookBub serves the ad of the highest bidder targeting that reader at that moment.
However, having pointed out some of the drawbacks, it’s also an inescapable fact that BookBub is undoubtedly the giant of the book promotion sites and can send your book soaring in sales if you get it right. Successful advertising requires careful targeting and great eye-catching creatives to get a healthy return on investment.