Percentage of Search impressions lost because your daily budget was too low to show ads for all eligible searches.
What is Search Lost IS (Budget)? Lost IS (Budget): % of impressions lost due to insufficient budget. Part of: IS + Lost IS (Budget) + Lost IS (Rank) = 100%. >20% signals growth opportunity. Fix by increasing daily budget 40-50% (not 1:1 due to CPC increases). Always verify campaign is profitable before scaling budget.
Search Lost IS (Budget) measures the percentage of Search Network impressions your ads didn't receive due to insufficient daily budget. When your campaign runs out of budget partway through the day, it stops showing ads for remaining searches—these missed impressions are captured in Lost IS (Budget). Formula: Search Impression Share + Lost IS (Budget) + Lost IS (Rank) = 100%. If your campaign has 60% Impression Share and 25% Lost IS (Budget), you're missing 25% of eligible impressions purely due to budget constraints (remaining 15% is Lost IS Rank). High Lost IS (Budget) (>20%) signals clear growth opportunity: increasing budget directly captures more traffic at similar efficiency. Available at campaign level only in Google Ads. Updated within 1-2 days.
Official Source: Definition verified from Google Ads Help Center (Last verified: January 2026)
"Search lost IS (budget) is the percentage of time that your ads weren't shown on the Search Network due to insufficient budget."
E-commerce pet supplies store runs Search campaign with $500/day budget. Search Impression Share 52%, Lost IS (Budget) 38%, Lost IS (Rank) 10%. Campaign is profitable: ROAS 4.2x, CPA $32 (target $50). Wants to scale.
Current State: - Daily budget: $500 - IS: 52% + Lost IS (Budget): 38% + Lost IS (Rank): 10% = 100% - Monthly cost: $15,000 - Conversions: 468 orders/month - ROAS: 4.2x - CPA: $32 (profitable, target $50) Opportunity: 38% Lost IS (Budget) → missing 38% of traffic due to budget Budget Increase: Increase budget 55% ($500 → $775/day) to capture most of 38% lost impressions Projected Results (if CPA/ROAS maintain): Monthly budget: $15,000 → $23,250 (+$8,250) Expected impression share: 52% → 85% (+33pp) Projected conversions: 468 → 745 (+59%, proportional to IS increase) Expected ROAS: ~4.0x (slight decline due to marginal traffic, still profitable) Expected CPA: ~$36 (+12%, acceptable within $50 target) Actual Results after 30 days ($775/day budget): - Search IS: 52% → 82% (+30pp, captured most lost IS) - Lost IS (Budget): 38% → 8% (budget no longer primary constraint) - Lost IS (Rank): 10% → 10% (unchanged, not budget-related) - Monthly cost: $22,680 (vs $15,000 baseline) - Conversions: 702 (vs 468 baseline, +50%) - ROAS: 3.9x (slight decline from 4.2x, still strong) - CPA: $38 (vs $32 baseline, +19% but under $50 target) Incremental Analysis: - Incremental spend: +$7,680/month - Incremental conversions: +234/month - Incremental revenue: $88,452 (assuming $378 AOV) - Incremental profit: $88,452 revenue - $7,680 spend = $80,772 - Return on incremental investment: 10.5x Key insight: High Lost IS (Budget) + profitable metrics = clear scale signal. Increasing budget captured 30pp of lost impression share, adding 234 monthly orders at slightly higher but still-profitable CPA. Without monitoring Lost IS (Budget), would have left $80K monthly profit on the table.
Lost IS (Budget) directly quantifies budget-constrained growth potential. A campaign with 30% Lost IS (Budget) is missing 30% of qualified traffic due to money, not ad quality. Increasing budget 40-50% can capture most of that traffic at similar CPCs/CPAs. This guides investment decisions: CFO asks "If I give you $10K more monthly budget, what happens?"—30% Lost IS (Budget) means you can profitably deploy that budget capturing missed traffic. However, increasing budget without monitoring can backfire: if Lost IS (Budget) was artificially high due to showing in expensive time periods (midnight-3am low-quality traffic), adding budget may serve expensive impressions at poor ROAS. Always validate profitability (CPA, ROAS) before aggressively increasing budget based on Lost IS (Budget) alone.
Increasing budget without checking profitability first—30% Lost IS (Budget) + $200 CPA (target $100) means adding budget pours money into unprofitable campaign. Fix profitability before scaling budget.
Assuming Lost IS (Budget) = exact budget increase needed—if Lost IS (Budget) is 25%, increasing budget 25% won't capture all of it. CPCs rise as you compete in more auctions. Increase budget 35-50% to capture 25% lost impressions.
Ignoring dayparting insights—campaign out of budget at 2pm daily means budget is split across all 24 hours. Concentrate budget in high-converting hours (9am-5pm business hours) before adding more.
Use Lost IS (Budget) to size budget increases: Current budget $1,000/day, Lost IS (Budget) 30% → increase to $1,400-$1,500/day (40-50% increase) to capture most missed impressions. Monitor for 1 week, then adjust.
Check Hour of Day report before increasing budget for Lost IS (Budget)—if campaign runs out of budget at 10am, it's missing prime afternoon hours. Redistribute budget across fewer high-performing hours before adding more.
Set alerts for Lost IS (Budget) >15% on profitable campaigns—automate monthly check: if profitable campaign has >15% Lost IS (Budget), flag for budget increase review. Ensures you don't miss growth opportunities.
Prioritize budget increases by profitability × Lost IS—Campaign A: ROAS 6x, Lost IS (Budget) 35%. Campaign B: ROAS 2x, Lost IS (Budget) 45%. Increase Campaign A budget first despite lower Lost IS—better return on incremental investment.
Percentage of impressions your ads received out of total eligible impressions on Google Search Network (actual impressions ÷ eligible impressions × 100).
Percentage of Search impressions lost because your Ad Rank was too low to show ads in auctions (due to low bids or poor Quality Score).
The average amount you're willing to spend on a campaign each day over the course of a month.
A score that determines your ad position and whether your ad shows at all, calculated using bid amount, Quality Score, and other auction-time factors.
No, increase budget by 40-50% to capture most of that 30% Lost IS (Budget). Here's why: When you increase budget, two things happen: (1) You compete in more auctions (the goal), and (2) CPCs slightly increase because you're now competing in auctions you previously couldn't afford (marginal impressions are more expensive). Example: Current setup—$1,000/day budget, 60% IS, 30% Lost IS (Budget), $5 CPC. If you increase budget exactly 30% to $1,300/day, you'll capture some lost impressions, but CPCs will rise to ~$5.50 as you bid in more competitive auctions. The result: Instead of capturing all 30% lost impressions (taking IS from 60% → 90%), you only capture ~18-22pp (taking IS to ~78-82%). To reliably capture most of 30% Lost IS (Budget) and reach 85-88% IS, increase budget 45-55% ($1,000 → $1,450-$1,550/day), accounting for CPC inflation. General rule: Target Lost IS (Budget) reduction = 0.6 to 0.7 × Budget increase percentage. If Lost IS (Budget) is 30% and you want to reduce it to <10% (capturing 20-25pp), increase budget by 30-40%. If Lost IS (Budget) is 20% and you want to reduce it to <5%, increase budget by 25-30%. Monitor results after 1 week, adjust as needed. Sometimes CPCs rise less than expected (you capture full Lost IS with smaller budget increase), sometimes more (need additional budget).
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