The most likely reason Google is withholding impressions for your ads is because of budget restrictions. Based on user traffic patterns, Google will pace your ads throughout the day to prevent your budget from being eaten up too early. If you are meeting your budget each day, and you donâ€™t have your ad delivery settings set to accelerated, this is a good indication that your ads are being restricted due to budget.
Ad rank is another likely cause for lost impressions.Â If your keywords are averaging a position of eight or lower you may be missing impressions by appearing on page two or worse in the search results. Simply increasing your keyword bids and/or quality scores will improve your positions and reduce your missed impressions due to ad rank.
Unfortunately, even with an unrestricted budget Google will still limit the number of impressions you receive. This is based entirely from a revenue perspective. Simply put, Google wants to show the ads that are making them the most money more often. This happens on a revenue per impression basis, therefore ads with high quality scores, CTRs, and max bids typically have the highest impression share.
You can view your impression share percentages in your AdWords account by clicking on the Campaigns tab and enabling Competitive metrics under Columns. This will detail if you are losing impressions based on budget, ad rank, or both. To increase your impression share, working on improving your ad and keyword quality scores will be the most effective approach. Increasing your bids will help as well but may not be the most profitable.