How to do a PPC forecast

Tom Shurville | 18th June 2015 |

PPC forecasting is an integral part of managing a paid search account. One of the most useful types of forecast is one which tells us how much we can spend based on our existing keyword list.

Did anyone ever ask you ‘how much do I need to spend to get full impression share for my keywords?’ or ‘how much can I spend without changing the structure of the account?’

We can guess but the most accurate way, of course, is to base our predictions on data.

This is how we do PPC forecasting:

  1. Start with downloading a keyword report from Google Ads for the last 30 days to give us robust and up to date data.

table 1

The first metric to be calculated is Market impressions, giving us the total number of possible impressions for that keyword. Market impressions is impressions divided by impression share (%).

table 22. Once we have market impressions, we can start to forecast. Assuming we will go after more generic terms, we should drop our CTR% by about 5%. Applying this reduced CTR% to our market impressions we can forecast traffic.

table 3

 3. Again, following the same principle we should expect a higher CPC. The reasoning behind this is that we will go after more generic keywords (our ratio of brand/longtail to generic will change) and we will go after higher positions (to reduce impression share lost to rank). Multiplying our ‘potential traffic’ by our new higher CPC we can forecast what we would expect to spend to gain full impression share for our current keyword list.

table 4


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