ROAS is decreasing: first confirm you’re looking at the same “ROAS” as before
ROAS is a ratio, so it drops for only two reasons
Return on ad spend is simply conversion value divided by cost. That means your ROAS can fall even if your business is stable, as long as either (a) reported conversion value goes down, (b) ad spend goes up, or (c) both happen at once. The fastest wins usually come from proving which side of the fraction moved first: tracking/value/reporting (the numerator) or auction costs/traffic mix (the denominator).
Make sure your reporting columns still match what your bidding is optimizing for
A very common “mystery ROAS drop” is actually a reporting mismatch. In many accounts, the Conversions and Conversion value columns only include the conversion actions currently set as primary for optimization, while secondary actions show up in All conv. and All conv. value. If someone recently changed which actions are primary (or changed campaign conversion goals), your reported conversion value can drop overnight even when real sales didn’t.
Exclude the conversion delay period when judging “recent” ROAS
If you evaluate ROAS including the most recent days where conversions are still “in flight,” you’ll almost always understate performance—especially for longer consideration cycles. This matters even more right after you change targets, budgets, or conversion setup. A practical approach is to compare two equivalent windows that both sit far enough in the past to be “fully baked” (for example, look at 14–28 days ago versus the prior 14-day window, rather than yesterday versus last week).
The most common reasons ROAS decreases (and how to diagnose each one)
1) Your conversion tracking or conversion value collection is incomplete
If fewer conversions are being captured—or if conversion events are firing without complete value/user-provided data—ROAS will fall even when traffic quality is unchanged. This can happen after site releases, checkout changes, consent implementations, tag refactors, or when only some conversion pages are correctly instrumented.
If you rely on enhanced conversions, confirm it’s transmitting properly on every page where the conversion tag fires, and use the platform diagnostics after the system has had time to process the new signals (it’s normal to need a few days before diagnostics fully populate). If the tag fires but key parameters are empty on some pages, you’ll often see a slow bleed in reported performance rather than an obvious “tracking broke” outage.
2) You changed conversion goals (primary vs secondary) and your ROAS “numerator” shrank
ROAS is only as good as the conversion actions included in the conversion value column you’re using. When teams add new actions, demote purchase actions to secondary, switch goals at the campaign level, or split goals by campaign type, you can unintentionally remove meaningful value from the primary columns. The result looks like declining ROAS, but it’s really a measurement scope change.
This also comes up when you begin including additional omnichannel actions (like store-related conversions) in the set of conversions used for optimization. Historical reporting won’t retroactively “rebuild” the past using your new setting, so trend lines can look jagged right at the change date.
3) You shortened conversion windows, so late conversions stopped counting
If your conversion window was reduced (for example, from 30 days to 7 days), conversions that happen after that window simply no longer appear in reports. That can instantly reduce recorded conversion value and make ROAS look worse—especially in higher-AOV, longer-cycle categories. Window changes only apply going forward, which creates a clear “break” in trend lines starting on the change date.
4) You changed attribution settings/models and the credit shifted away from the campaigns you’re watching
Attribution changes can move conversion value between campaigns without changing total sales. If you recently adjusted attribution model settings or started using different attribution reporting columns, some campaigns will “lose” credit and others will “gain” it. That’s not inherently bad—but if you judge ROAS at the campaign level without accounting for the shift, it can look like a real decline.
Also watch out for campaign-type-specific reporting columns. Certain campaign types offer alternative “platform comparable” style columns that intentionally use different methodologies than the standard conversion columns. Mixing these views when comparing against Search, Shopping, or Performance Max can create false ROAS conclusions.
5) Smart Bidding is reacting to changes faster than your conversions can be observed
When you change ROAS targets, budgets, conversion goals, or the conversion values themselves, the bidding system can start optimizing toward the new goal quickly, but performance measurement lags because conversions lag. In practice, you should avoid stacking multiple target changes inside a single conversion cycle (the typical time it takes clicks to convert). Doing so gives the system moving goalposts before it can “see” the outcome of the previous change.
Another overlooked trigger: if you just started reporting conversion value (or changed the way values are sent), it takes time for value signals to come through consistently enough for value-based bidding to behave predictably. Expect a stabilization period before you treat the new ROAS as “truth.”
6) Your conversion values became less representative of profit (customer mix shifts)
ROAS can decrease even while conversions hold steady if average conversion value drops. Common causes include heavier discounting, selling lower-margin items, higher refund rates, or a surge of returning customers who buy smaller baskets. If you’re actively optimizing toward new customer acquisition, you may also be trading short-term ROAS for higher lifetime value—especially if your reporting doesn’t add incremental value for new customers in a structured way.
If you use conversion value rules to weight higher-value segments (by location, device, or audience), a configuration change can materially alter the value signal. Value rules are powerful, but they’re also easy to misapply if the “when/then” logic doesn’t match how your business actually values customers.
7) Post-purchase adjustments (returns/cancellations) are pulling value down
If you restate or retract conversion values to account for returns, partial refunds, or cancellations, reported conversion value will drop—often with a time delay. That can make ROAS look like it’s “randomly” falling days or weeks after a promotion. This is usually a good sign (your measurement is more honest), but it does require changing how you evaluate recent performance and how aggressively you set ROAS targets.
8) Costs rose due to auction pressure, budgets, or targeting changes
Sometimes ROAS is fine—the denominator moved. If cost per click rises because of competition, seasonality, broader match expansion, looser targeting, or more aggressive budget pacing, your spend can grow faster than conversion value. This is especially common after major structural edits (new campaign types, new bidding strategy, changes to locations/languages/schedules, audience expansion, or large creative refreshes) because traffic mix shifts before your site and funnel “catch up.”
A systematic fix: the fastest way to recover ROAS without guesswork
Step 1: Identify whether the drop is “value down” or “cost up”
- Compare conversion value, cost, and conversion value/cost over two equal time ranges that exclude the newest conversion-delay days.
- Check whether value per conversion fell (basket size/mix issue) or whether conversion rate fell (traffic/landing/funnel issue).
- Confirm whether the set of conversions included in reporting changed (primary vs secondary, campaign goals, newly included actions).
Step 2: Audit tracking and value integrity (the “ROAS numerator” health check)
In mature accounts, most ROAS declines trace back to measurement integrity. Validate that your purchase conversion fires on the correct confirmation state, fires once per order, and consistently includes value and currency. If you use enhanced conversions, ensure it’s implemented across all relevant conversion pages and that diagnostics show healthy coverage after the system has had time to process recent changes.
If you recently changed conversion windows, attribution settings, or which conversions are primary, mark the exact change date and evaluate performance before/after using consistent definitions—otherwise you’ll end up “optimizing” against a reporting artifact.
Step 3: Stabilize Smart Bidding before making more changes
If you’re on value-based automated bidding, treat ROAS target edits like surgery, not a dial you spin daily. Make one meaningful change, then wait at least one to two conversion cycles to judge impact. When you do set a ROAS target, ground it in recent historical conversion value/cost from a period that excludes conversion delay, and avoid setting a target higher than what the account can realistically sustain, because overly aggressive targets often reduce traffic volume and can starve the system of the data it needs to improve.
Step 4: Improve value quality, not just volume
If the core issue is lower value per conversion, start by aligning the value signal to what the business truly wants. That may mean refining conversion values (so different purchases or customer types are valued appropriately), using value rules carefully where they genuinely reflect incremental value, and ensuring returns/cancellations are handled consistently so you’re not optimizing toward revenue that won’t be kept.
Step 5: Control the “cost side” with tighter intent and cleaner traffic
If the core issue is cost rising faster than value, focus on tightening query quality and traffic mix. In practice, that usually means reducing wasted spend from low-intent queries/placements, aligning ad messaging to higher-intent segments, and ensuring landing pages match the promise of the ad so conversion rate doesn’t erode as you scale. When budgets are constrained or frequently changed, expect more volatility; stable budgets and fewer structural edits typically produce more stable ROAS because the system can learn and allocate efficiently.
Let AI handle
the Google Ads grunt work
| Area | What to check | Why ROAS can drop | How to diagnose in Google Ads | Relevant Google Ads docs |
|---|---|---|---|---|
| ROAS definition & timeframes | Confirm you’re looking at the same ROAS and date ranges as before. | ROAS is conversion value ÷ cost, so it falls when reported value goes down, costs go up, or both. Comparing different “flavors” of ROAS or including days with incomplete conversion data makes it look like performance dropped when it didn’t. |
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| Conversion tracking & value collection | Check if all conversions and their values are still being recorded correctly. | If tags stop firing, fire multiple times, or fire without value/currency or user data, reported conversion value drops even when traffic quality is unchanged. |
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| Primary vs secondary conversions & goals | Confirm which conversion actions are set as primary, which are secondary, and which goals each campaign is optimizing toward. | Switching purchase actions to secondary, changing campaign conversion goals, or newly including/excluding omnichannel actions can remove value from the Conversions and Conversion value columns overnight, making ROAS appear to fall even when true sales are unchanged. |
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| Conversion windows | Review how long each conversion action’s window is and whether it was shortened recently. | Reducing a conversion window (for example from 30 days to 7 days) stops counting conversions that occur after the new window, causing a step change down in reported conversion value and ROAS, especially for longer purchase cycles. |
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| Attribution models & reporting views | Confirm whether attribution models or attribution reporting columns changed. | Shifting from one attribution model to another, or using alternative attribution-style columns for certain campaign types, moves conversion value between campaigns without changing total sales. Some campaigns “lose” credit and show lower ROAS purely due to the model change. |
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| Smart Bidding changes vs conversion lag | Look at recent changes to ROAS targets, budgets, conversion goals, or value definitions versus your typical conversion delay. | The bidding system can adjust bids immediately based on new targets or value signals, but conversions may take days or weeks to materialize. Stacking multiple target or goal changes within a single conversion cycle creates noisy, misleading short-term ROAS trends. |
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| Average order value & customer mix | Check if average conversion value or profit per conversion has fallen even when conversion count is steady. | More discounted orders, lower-margin products, higher refund rates, or a shift toward smaller repeat purchases reduce average conversion value. ROAS drops even if the number of conversions and traffic quality are stable. |
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| Returns, cancellations, and value adjustments | Review how post-purchase events (returns, partial refunds, cancellations) are fed back into Google Ads. | If you restate or retract conversion values to account for returns and cancellations, reported conversion value for past days will decrease and historical ROAS will drift down, especially after promotions. |
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| Auction pressure, budgets, and targeting | Check whether cost per click, impression share, or traffic mix changed around the time ROAS began to fall. | ROAS can decline when the denominator (cost) rises faster than conversion value due to auction competition, broader match or audience expansion, relaxed location/language settings, or aggressive budget increases. |
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| Systematic ROAS recovery – measurement | Step 1–2: Separate “value down” vs “cost up” and audit measurement integrity. | Most “mysterious” ROAS drops trace back to measurement changes or inconsistencies rather than true demand shifts. Fixing tracking and value inputs often restores ROAS without major bidding overhauls. |
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| Systematic ROAS recovery – bidding & value strategy | Step 3–5: Stabilize Smart Bidding, improve value quality, and tighten traffic. | Frequent target tweaks, misaligned value signals, and loose targeting make ROAS volatile. Grounding targets in realistic recent data, sending high‑quality value signals, and improving traffic intent stabilizes and improves ROAS. |
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If your ROAS is decreasing, it usually comes down to a shift in one side of the ratio (conversion value down, costs up, or both) or a reporting/measurement change that makes performance look worse than it really is—common culprits include incomplete conversion value tracking, primary vs. secondary conversion or goal changes, shortened conversion windows, attribution model updates, Smart Bidding reacting faster than your conversion lag, changes in average order value (discounting, product mix, refunds), or higher auction pressure and broader targeting driving up CPCs. If you want a structured way to spot what changed and what to do next without living in spreadsheets and change history, Blobr connects to your Google Ads account and continuously analyzes performance, then turns best practices into concrete recommendations, with specialized AI agents that can help tighten wasted traffic, align keywords to the right landing pages (Keyword Landing Optimizer), and refresh underperforming ad assets (Headlines Enhancer) while you stay in control of what gets applied.
ROAS is decreasing: first confirm you’re looking at the same “ROAS” as before
ROAS is a ratio, so it drops for only two reasons
Return on ad spend is simply conversion value divided by cost. That means your ROAS can fall even if your business is stable, as long as either (a) reported conversion value goes down, (b) ad spend goes up, or (c) both happen at once. The fastest wins usually come from proving which side of the fraction moved first: tracking/value/reporting (the numerator) or auction costs/traffic mix (the denominator).
Make sure your reporting columns still match what your bidding is optimizing for
A very common “mystery ROAS drop” is actually a reporting mismatch. In many accounts, the Conversions and Conversion value columns only include the conversion actions currently set as primary for optimization, while secondary actions show up in All conv. and All conv. value. If someone recently changed which actions are primary (or changed campaign conversion goals), your reported conversion value can drop overnight even when real sales didn’t.
Exclude the conversion delay period when judging “recent” ROAS
If you evaluate ROAS including the most recent days where conversions are still “in flight,” you’ll almost always understate performance—especially for longer consideration cycles. This matters even more right after you change targets, budgets, or conversion setup. A practical approach is to compare two equivalent windows that both sit far enough in the past to be “fully baked” (for example, look at 14–28 days ago versus the prior 14-day window, rather than yesterday versus last week).
The most common reasons ROAS decreases (and how to diagnose each one)
1) Your conversion tracking or conversion value collection is incomplete
If fewer conversions are being captured—or if conversion events are firing without complete value/user-provided data—ROAS will fall even when traffic quality is unchanged. This can happen after site releases, checkout changes, consent implementations, tag refactors, or when only some conversion pages are correctly instrumented.
If you rely on enhanced conversions, confirm it’s transmitting properly on every page where the conversion tag fires, and use the platform diagnostics after the system has had time to process the new signals (it’s normal to need a few days before diagnostics fully populate). If the tag fires but key parameters are empty on some pages, you’ll often see a slow bleed in reported performance rather than an obvious “tracking broke” outage.
2) You changed conversion goals (primary vs secondary) and your ROAS “numerator” shrank
ROAS is only as good as the conversion actions included in the conversion value column you’re using. When teams add new actions, demote purchase actions to secondary, switch goals at the campaign level, or split goals by campaign type, you can unintentionally remove meaningful value from the primary columns. The result looks like declining ROAS, but it’s really a measurement scope change.
This also comes up when you begin including additional omnichannel actions (like store-related conversions) in the set of conversions used for optimization. Historical reporting won’t retroactively “rebuild” the past using your new setting, so trend lines can look jagged right at the change date.
3) You shortened conversion windows, so late conversions stopped counting
If your conversion window was reduced (for example, from 30 days to 7 days), conversions that happen after that window simply no longer appear in reports. That can instantly reduce recorded conversion value and make ROAS look worse—especially in higher-AOV, longer-cycle categories. Window changes only apply going forward, which creates a clear “break” in trend lines starting on the change date.
4) You changed attribution settings/models and the credit shifted away from the campaigns you’re watching
Attribution changes can move conversion value between campaigns without changing total sales. If you recently adjusted attribution model settings or started using different attribution reporting columns, some campaigns will “lose” credit and others will “gain” it. That’s not inherently bad—but if you judge ROAS at the campaign level without accounting for the shift, it can look like a real decline.
Also watch out for campaign-type-specific reporting columns. Certain campaign types offer alternative “platform comparable” style columns that intentionally use different methodologies than the standard conversion columns. Mixing these views when comparing against Search, Shopping, or Performance Max can create false ROAS conclusions.
5) Smart Bidding is reacting to changes faster than your conversions can be observed
When you change ROAS targets, budgets, conversion goals, or the conversion values themselves, the bidding system can start optimizing toward the new goal quickly, but performance measurement lags because conversions lag. In practice, you should avoid stacking multiple target changes inside a single conversion cycle (the typical time it takes clicks to convert). Doing so gives the system moving goalposts before it can “see” the outcome of the previous change.
Another overlooked trigger: if you just started reporting conversion value (or changed the way values are sent), it takes time for value signals to come through consistently enough for value-based bidding to behave predictably. Expect a stabilization period before you treat the new ROAS as “truth.”
6) Your conversion values became less representative of profit (customer mix shifts)
ROAS can decrease even while conversions hold steady if average conversion value drops. Common causes include heavier discounting, selling lower-margin items, higher refund rates, or a surge of returning customers who buy smaller baskets. If you’re actively optimizing toward new customer acquisition, you may also be trading short-term ROAS for higher lifetime value—especially if your reporting doesn’t add incremental value for new customers in a structured way.
If you use conversion value rules to weight higher-value segments (by location, device, or audience), a configuration change can materially alter the value signal. Value rules are powerful, but they’re also easy to misapply if the “when/then” logic doesn’t match how your business actually values customers.
7) Post-purchase adjustments (returns/cancellations) are pulling value down
If you restate or retract conversion values to account for returns, partial refunds, or cancellations, reported conversion value will drop—often with a time delay. That can make ROAS look like it’s “randomly” falling days or weeks after a promotion. This is usually a good sign (your measurement is more honest), but it does require changing how you evaluate recent performance and how aggressively you set ROAS targets.
8) Costs rose due to auction pressure, budgets, or targeting changes
Sometimes ROAS is fine—the denominator moved. If cost per click rises because of competition, seasonality, broader match expansion, looser targeting, or more aggressive budget pacing, your spend can grow faster than conversion value. This is especially common after major structural edits (new campaign types, new bidding strategy, changes to locations/languages/schedules, audience expansion, or large creative refreshes) because traffic mix shifts before your site and funnel “catch up.”
A systematic fix: the fastest way to recover ROAS without guesswork
Step 1: Identify whether the drop is “value down” or “cost up”
- Compare conversion value, cost, and conversion value/cost over two equal time ranges that exclude the newest conversion-delay days.
- Check whether value per conversion fell (basket size/mix issue) or whether conversion rate fell (traffic/landing/funnel issue).
- Confirm whether the set of conversions included in reporting changed (primary vs secondary, campaign goals, newly included actions).
Step 2: Audit tracking and value integrity (the “ROAS numerator” health check)
In mature accounts, most ROAS declines trace back to measurement integrity. Validate that your purchase conversion fires on the correct confirmation state, fires once per order, and consistently includes value and currency. If you use enhanced conversions, ensure it’s implemented across all relevant conversion pages and that diagnostics show healthy coverage after the system has had time to process recent changes.
If you recently changed conversion windows, attribution settings, or which conversions are primary, mark the exact change date and evaluate performance before/after using consistent definitions—otherwise you’ll end up “optimizing” against a reporting artifact.
Step 3: Stabilize Smart Bidding before making more changes
If you’re on value-based automated bidding, treat ROAS target edits like surgery, not a dial you spin daily. Make one meaningful change, then wait at least one to two conversion cycles to judge impact. When you do set a ROAS target, ground it in recent historical conversion value/cost from a period that excludes conversion delay, and avoid setting a target higher than what the account can realistically sustain, because overly aggressive targets often reduce traffic volume and can starve the system of the data it needs to improve.
Step 4: Improve value quality, not just volume
If the core issue is lower value per conversion, start by aligning the value signal to what the business truly wants. That may mean refining conversion values (so different purchases or customer types are valued appropriately), using value rules carefully where they genuinely reflect incremental value, and ensuring returns/cancellations are handled consistently so you’re not optimizing toward revenue that won’t be kept.
Step 5: Control the “cost side” with tighter intent and cleaner traffic
If the core issue is cost rising faster than value, focus on tightening query quality and traffic mix. In practice, that usually means reducing wasted spend from low-intent queries/placements, aligning ad messaging to higher-intent segments, and ensuring landing pages match the promise of the ad so conversion rate doesn’t erode as you scale. When budgets are constrained or frequently changed, expect more volatility; stable budgets and fewer structural edits typically produce more stable ROAS because the system can learn and allocate efficiently.
