CPM, also known as cost per mille, is the amount you’re willing to pay per thousand impressions on your advertisement on our page. For instance, if you bid $2.00 CPM, that means you have to pay $2.00 per 1000 impressions of your product on our web page.
How do I bid and set my budget?
The more you’re willing to pay for impressions (i.e. the higher your CPM), the higher the likelihood of getting your advertisement shown.
The way bids work is - the highest bidder will always get the impressions first until they run out of budget. Then, the next highest bidder will receive the featured spot. This goes on until there are no more impressions or bids left.
In the example above, Bidder would get the first 25,000 impressions (as their budget is $100, and they’re paying $4 CPM). When they run out of budget, it goes to Bidder 2 - who gets the next 40,000 impressions (as their budget is $100, and they’re paying $2.50 CPM). The same goes for Bidder 3 - however, their budget is not fully used as there aren’t enough impressions left. Finally, Bidder 4 completely misses out as there aren’t enough impressions.
As you can see in the above example - the higher your CPM bid is, the higher in the priority you’ll take when it comes to getting a spot.
You'll see that there are two slots to input when bidding - one for the price per thousand impressions, and one for your budget.
Something that's important to keep in mind whilst bidding are these equations:
CPM = Cost per thousand LIMIT = Price limit you want to pay Figuring out how many impressions you'd get: (LIMIT / CPM) * 1000 = estimated impressions
Please be sure to read our article on how the auctions bid limit works.
Minimum Bids, Impressions, and Increments
When bidding for impressions, each category has a minimum bid that must be met. Globally, this limit is currently set to $1 USD. However, each category might have a higher bid limit than this.
You must also bid for at least one thousand impressions for a category. An easy way to make sure you are meeting this minimum is to check if your CPM and your limit are the same. For example, if you bid $1 @ $1.00 then you are bidding for one thousand impressions. The only time that you can bid for less than one thousand impressions is if the category you are bidding on has an estimated impression count of less than 1,000.
If you are bidding on a category that already has bids purchasing all of the estimated impressions, to place a winning bid of your own, you must place your CPM a certain increment based on how much the current lowest winning bid is. Winning bids include any bids that have estimated impressions on them.
if a category has 10k impressions available, and the leaderboard currently looks like this -
Product 1: $2 @ $10 (gets 5k impressions)
Product 2: $1.5 @ 20 (gets 5k impressions)
Product 3: $1 @ 100 (gets 0 impressions)
If you want to bid for impressions, you must bid at least $.25 above the lowest winning spot (AKA Product 2), which means you need to bid at least $1.75. If you do not want a winning spot you can bid $1.01 - $1.49.
Here is a helpful chart on the minimum increments for different budgets:
Paying for your Impressions
Since the amount you initially pay for is based on the estimated amount of impressions from previous data, any impressions that are overcharged will then be refunded to you in credits, if applicable. In addition, if your budget was not used up and there happens to be more impressions than expected, you will be charged the additional amount afterwards, via retroactive charging.