What is Search lost IS (budget)?

The column is labelled Search lost IS (budget) in the interface. Google's definition reads: the percentage of time that your ads weren't shown on the Search Network due to insufficient budget. This data is available at the campaign level only. Search impression share, next to it, is defined differently: the impressions you've received on the Search Network divided by the estimated number of impressions you were eligible to receive.

Where it can and cannot appear. Google notes that in report editor, search lost IS (budget) is available in the Campaigns report, but not in the Ad group report, and that as of June 2022 the metric was removed from any previously saved reports that also used 'Ad group', 'Search Keyword', or 'Label (Ad group)'. Our reading: a saved report that used to carry the column and now does not has lost the column. It is not telling you the campaign stopped being short of budget.

Two timing facts are worth knowing. Google says all impression share metrics are updated within 1 to 2 days. Our reading: the most recent day in a window may not be reported yet. And for Shopping campaigns, impression share is available from September 2013, except for 'search lost IS (budget)', which is available from November 2014.

Google's general tips for improving impression share include increasing your campaign budget, and say your budget controls how often an ad is shown. They also warn that if you increase your regional targets you may see a decrease in impression share, because there are now more potential impressions available, and suggest re-adjusting your budget so that it'll cover the costs of your new campaign settings. Google reports impression share metrics separately for each campaign type and does not aggregate them across the account. Our reading: this column on a Search campaign is not a reading of a Shopping or Display campaign in the same account.