“Back to School” week continues as Hayley provides formulas that you should consider using to determine your visibility and spend during this important time of the year.  

If you haven’t yet, read Amanda’s post on “4 Steps  To Back To School Success.

Back to school means increased consumer shopping. Your target audience will be in the market to purchase and may not be back until next year. Make sure you are present when they are showing the signs of researching, comparing and purchasing.

With this increased volume come potentially higher cost per clicks (CPCs) and therefore the need for larger budgets. If you are in an industry that relies on this time period to garner the most revenue, you are likely prepared. If not, don’t fret! I’ve outlined a tutorial to project ad spend spend during back to school season.

First, go into AdWords and pull a campaign report for last year’s back to school season. It is important to look at last year’s period so you can get an accurate portrayal of what type of volume (impressions) you could garner during this time frame.

Include the following columns:

Image of search impression share columns

This information can be used to show you where you stand in terms of how you can most quickly and easily boost your share of voice (impression share). Most importantly, the above should give you the impression share lost due to budget. This is the most straightforward way to boost your share. This percentage equals the amount of impressions you can garner by simply increasing your campaign daily budgets while keeping bids, campaign structure and settings consistent.

For example, if you have 30% impression share loss due to budget, you can figure out how much budget you will need to gain that 30% using a simple formula. Take your current impression share percentage and the total number of impressions you have. Now you want to find out what the total availability is by dividing your total impressions by your impression share percentage.


Impressions / Search Impression Share = Total Impressions Available

234,655 / .45 = 521,456

Now that you know what the total opportunity is you can figure out how many impressions you are loosing due to budget using your loss due to budget percentage.


Total Impressions Available * Impression Share Loss Due to Budget = Number of Impressions You Are Loosing Due to Budget

521,456 * .3 = 156,437

Now that you know how many impressions you could gain by expanding budget caps you can start to back into the actual cost of doing this. Take your average CTR % and multiply by the total available impressions.


Avg CTR % * Total Impressions Available = Total Incremental Clicks

1.34% * 156,437 = 2,096

Next, using your average CPC you can determine how much cost you should add to your daily budgets. Do this by multiplying the incremental clicks by the average CPC.


Avg CPC * Total Incremental Clicks = Additional Campaign Daily Spend

$2.10 * 2,096 = $4,401.60

At the most basic level you can now increase you average daily spend by this calculated amount and garner all of your missed impressions.

The next step is to take a look at the impression share loss due to rank. These are the impressions you loose due to a low bid, quality score and just generally being off the first page of results. To get the best view of where you should focus when it comes to projecting this cost you should pull a report at the keyword level.

Include the following columns:

Image of bid columns

Now that you have your budget gap filled, you can start to fill your loss due to rank. Run the same formula we used previously, only this time use Impressions Share Loss Due to Rank percentage. You will want to do this by keyword.

You will want to find out each keyword’s impression share loss due to rank. Do this by inserting a column and the following formula.

Total Impressions Available (Impressions / Search Impression Share = Total Impressions Available) * Impressions Share Loss Due to Budget Percentage

This formula will give you the incremental impressions you can gain by increasing your rank.

For the next step, take a look at the columns that include your estimated first page and top page bids. First page bids will give you the CPC needed to ensure your ad will show on the first page. Similarly, the top of page bid will give you the keyword CPC needed to ensure ad placement in the 1st – 3rd position. The top page bids will be more expensive than first page bids.

Insert a column and take your incremental impressions and multiply them by the keyword’s average CTR %. This will give you the incremental clicks. Once you have this metric you can insert two more columns. In the first, multiply the incremental clicks by the top of page CPC. This will give you the incremental cost needed to boost your keyword to top of page for each keyword. In the second do the same for first page bids.

Now you should have two columns that, when totaled, will give you incremental cost for garnering the impressions and clicks lost due to rank. If top of page is too expensive then start with first page bids. Be sure to update your CPCs and campaign daily budget caps and make a note of the upload date. Set a reminder to revisit in two weeks. The CPCs needed to be in the first position or on the first page can change quite frequently.

Finally, take your additional budget from your Loss Due to Budget calculation and add it to the Loss Due to Rank budget. This number will give you a conservative estimate of what your back to school seasonal investment ‘could’ be.

Remember that these are estimates, so keep a close eye on your keyword status column and make sure you are not missing from the first page on any of your important terms.  You may also find that there is more, or fewer impressions available this year due to year over year changes in your industry. Be prepared to keep a close eye on your campaigns to make sure your budget is being spent appropriately.