Lost IS (Budget)
Paid MediaAlso: Lost Impression Share (Budget) · Search Lost IS Budget
Quick definition
Lost impression share (Lost IS) due to budget is the percentage of times your Google Ads or Microsoft Ads campaign was eligible to show but didn't, because your daily budget ran out. It's reported alongside impression share (IS) and Lost IS (rank), and the three figures always sum to 100 percent.
A high result means demand exceeds your budget, not that your ads are weak. Check CPA and ROAS before deciding whether to raise spend.
How it varies across Australia
Lost IS (budget) varies widely across Australian accounts depending on category competitiveness and how tightly budgets are set relative to demand. High-intent retail and finance categories tend to run tighter, hitting budget caps earlier in the day, while niche B2B accounts often show low Lost IS (budget) but high Lost IS (rank) instead. The two numbers tell different stories and should never be read together as one problem.
See paid media efficiency benchmarks across Australian industries →What it actually means
Think of impression share like a queue at a popular cafe. Every time someone searches a keyword you're bidding on, you're eligible to join the queue for that auction. Impression share (IS) tells you what percentage of those queues you actually got seen in. Lost IS splits the misses into two causes: rank (your ad wasn't competitive enough to win the auction) and budget (your ad would have won, but the campaign ran out of money for the day before it got the chance).
This distinction matters because the fixes are opposite. Lost IS (rank) is a quality score or bid problem, you improve ad relevance, landing page experience or raise your maximum cost per click (CPC). Lost IS (budget) is a spend ceiling problem, you either raise the daily budget or you narrow targeting so the budget you already have stretches further across fewer, better auctions.
A campaign can have excellent quality score and still show high Lost IS (budget). That's not underperformance. That's a budget that's smaller than the demand for the keywords you're chasing.
Lost IS (budget) isn't a quality problem. It's a math problem. You're winning auctions you can't afford to keep winning.
How to calculate it
Lost IS (budget) = 100% minus Search Impression Share minus Lost IS (rank)
Worked example. Your campaign shows 62% search impression share and 8% Lost IS (rank). Lost IS (budget) = 100 - 62 - 8 = 30%. Nearly a third of your eligible auctions were missed purely because the daily budget ran out.
The Australian context
Australia's smaller auction pool means budget caps get hit earlier in the day for high-intent categories than in larger markets, especially in the morning search spike common in eastern states. Businesses running national campaigns across time zones sometimes see Lost IS (budget) climb specifically during Western Australian business hours when eastern budgets have already been spent for the day. Splitting budgets by state or dayparting can recover impression share that's otherwise lost to timing rather than genuine demand limits.
Where people get this wrong
Related terms
Common questions
Is high Lost IS (budget) a bad sign?
Not automatically. It means your ads are winning auctions but running out of daily budget before capturing all of them. If CPA and ROAS are healthy, it's often a strong signal to consider raising budget rather than a warning sign.
How do I fix Lost IS (budget)?
Raise the daily budget if efficiency metrics support it, or narrow targeting so the existing budget covers fewer, higher-value auctions. Dayparting and geographic splits can also help if losses cluster at specific times or locations.
What's the difference between Lost IS (budget) and Lost IS (rank)?
Lost IS (budget) means you'd have won the auction but ran out of money. Lost IS (rank) means your ad rank wasn't competitive enough to win regardless of budget. They require opposite fixes, so diagnosing which one applies matters before you act.
Do Search Impression Share, Lost IS (rank) and Lost IS (budget) always add up to 100 percent?
Yes. These three figures are designed to sum to 100 percent for any given campaign or keyword. If your reporting shows otherwise, check whether you're mixing date ranges or campaign segments.
Debrief
Get the next one
No spam. No fluff. Just the next article, straight to your inbox.
Keep exploring
About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
How we think →