Target ROAS tolerance is a percentage that tells Google Ads how far below a campaign's return on ad spend (ROAS) target its automated bidding may drift while it hunts for new search queries. It exists because a strict ROAS target makes Smart Bidding cautious: the system bids only where it already expects the target to be met, so queries without a conversion history rarely get a chance. Tolerance buys that chance. An advertiser accepts a lower return, up to a stated limit, in exchange for more traffic diversity and, in theory, more conversions.

The setting is not a bid strategy in its own right. It is the control at the centre of Smart Bidding Exploration, announced in May 2025, and since June 2026 the lever behind promotion mode, a scheduling tool for sales periods. As of October 2026 it applies only to campaigns bidding on Target ROAS or Maximize conversion value, and only inside Google's own ad products.

How the tolerance changes the target

The arithmetic is simple. Google subtracts the tolerance from the baseline target to produce an "effective" target, and the bidding system works toward that lower number. A campaign with a 200% Target ROAS and a 10% tolerance bids toward 180%, according to Google's setup page. The tolerance is a share of the target, not a number of percentage points, so 10% of a 500% target moves the effective target to 450%, not 490%.

The effective target feeds the usual auction-time calculation: Smart Bidding predicts conversion probability and value, then bids so that predicted value divided by cost lands near the target. A lower target raises the bid an auction can justify, so queries just below the old threshold now clear it.

Results need not stop there. Google's reporting guidance says actual ROAS should land "within about 15%" of the tolerance-adjusted figure while Exploration is active, according to the help page on measuring the feature. On a 200% target with a 10% tolerance, an outcome near 153% (180% less 15%) would still fall inside the range Google describes.

Settings, fields and typical values

In the Google Ads interface, the control sits in campaign settings under "Smart Bidding exploration", where a box labelled "Allow Smart Bidding to explore new traffic" switches it on and a tolerance is chosen. A PPC Land screenshot from May 2026 showed it as a slider set at 10%. Google recommends starting at 10%, according to its best practices page. Google's help pages do not publish the full range. The agency HawkSEM reported in October 2025 that advertisers could pick a tolerance between 10% and 30%.

Portfolio bid strategies can carry the setting too, which applies it to every campaign in the portfolio. That route is limited to Search campaigns. Portfolio bidding is not supported for standard Shopping or Performance Max campaigns running Exploration, Google says.

In the Google Ads API, the value is stored as target_roas_tolerance_percent_millis, an optional integer on both the MaximizeConversionValue and TargetRoas bidding messages. The field description, as shipped in Google's official Python client library, defines it as "the percent of ROAS (return on advertising spend) degradation tolerance allowed to increase traffic diversity and conversion volume", where 10,000 equals 10%. On the standalone TargetRoas message it is "only mutable for portfolio bidding strategies". A separate error blocks campaigns carrying a tolerance from AI Max experiments. The field is absent from API version 20 and present in version 21, whose client library was published on August 6, 2025, according to the Python Package Index.

The bid strategy report's "Avg. target ROAS" metric automatically factors in the tolerance, and a light green annotation marks the period when Exploration was on. Campaign columns count "unique search categories" with impressions, clicks and conversions. API version 22, released on October 15, 2025, added date segmentation for the matching unique query cluster metrics.

Who operates it

The setting is purely a buy-side control. Advertisers and agencies choose the tolerance; Google's bidding system decides which extra auctions to enter. Google pairs the feature with broad targeting, naming non-brand broad match keywords, dynamic search ads (DSA) and AI Max as the intended companions, because a tolerance can only widen reach if the campaign's targeting already permits wider queries.

Google warns that Exploration "won't work well" when a campaign is limited by budget and shows an alert in that case. HawkSEM listed at least 15 conversions in 30 days as a prerequisite. Google discourages testing on new campaigns without history, and advises excluding a ramp-up of one to two conversion cycles and running the feature for at least six weeks.

Origin and evolution

Google announced Smart Bidding Exploration on May 21, 2025, around Google Marketing Live, calling it "our biggest update to bidding in over a decade", according to the Google blog. The announcement spoke of "new, flexible ROAS targets" rather than tolerance. Based on internal data from March 11 to April 11, 2025, Google said campaigns using it saw on average 18% more unique search query categories with conversions and 19% more conversions.

Sources disagree on when it reached advertisers. PPC Land's June 2026 report described it as available for Search campaigns since 2024, which sits awkwardly with the May 2025 announcement. Google Ads Editor 2.11 added it as an opt-in for Search campaigns in 2025; PPC Land dated that release November 6, 2025, while other coverage placed it in September 2025.

Expansion came in steps. A toggle then began appearing in Performance Max accounts, Search Engine Land reported, and by May 2026 Exploration for Performance Max was running as a separate beta. On May 7, 2026, Josh Braverman, a group product manager for Google Ads, said Shopping and feed-based Performance Max campaigns would be able to "adjust your Target ROAS tolerance and capture new Shopping traffic", and that Search campaigns using the feature saw 27% more unique converting users on average. On June 15, 2026, Exploration became generally available for Performance Max campaigns without a product feed and entered beta for Shopping and feed-based Performance Max.

The same June package introduced promotion mode in beta for Search and Performance Max. "Promotion mode lets you set temporary changes to your ROAS tolerance and add extra daily budget during peak periods," according to Google's announcement. Windows run three to 14 days and switch off by themselves. "With Promotion mode, there's no need to remember to come back to turn it off," Ginny Marvin, Google's Ads Product Liaison, explained. While a window is active the baseline target is locked. A notice spotted by Arpan Banerjee read "You can't edit your Target ROAS while promotion mode is active", offering a tolerance edit instead, according to Search Engine Roundtable on September 25, 2026.

Why it matters for marketers

The meaning of a ROAS target was shifting. In June 2026 Google restored "Target ROAS" as a standalone strategy label, and from August 17, 2026 budget-limited campaigns began to be steered back toward the targets advertisers typed in rather than the better returns they had been getting. Smarter Ecommerce (smec) data showed the median budget-limited campaign beating its target by about 20%, a surplus that fell to about zero by August 31.

That made an explicit tolerance more significant, because some practitioners had set deliberately low targets to let the system explore. Joey Bidner, a freelance consultant, said some of his best accounts ran low Target ROAS settings for that reason, and he called the August change "one of the most self serving Google-centric changes we've seen in years". Tolerance formalises that trade in a separate, reportable setting. Marvin put Google's position this way: "We want advertisers to set targets that actually mean something to their business so we can appropriately act on it."

Limitations and disputes

The setting lowers efficiency by design. Jonni Lomax, company director at Lomax PPC, summarised both readings on X when the Performance Max toggle appeared: "Optimistically, this means that when competition is high, data quality is preserved," and, "Pessimistically, it will lower ROAS overall," according to Search Engine Land.

Evidence of benefit comes almost entirely from Google. The 18%, 19% and 27% figures are platform averages from internal data, not independently audited, and none measures incrementality. Google itself recommends pre- and post-test experiments to separate Exploration from seasonal demand. Visibility is limited: new queries reached through Exploration appear in the search terms report without a separate label, HawkSEM noted.

Google has not documented how promotion mode's tolerance combines with seasonality adjustments or an always-on Exploration tolerance. The budget condition is also awkward: Exploration needs uncapped budgets, yet the August 17 change hit exactly the budget-limited campaigns that had relied on overdelivery.

What it is not

Target ROAS is the efficiency goal itself; tolerance is a discount applied to it, while the baseline stays stored.

Seasonality adjustments tell Smart Bidding to expect a change in conversion rate over a set period and leave the ROAS target unchanged. Promotion mode changes the tolerance and the budget instead.

Meta's minimum ROAS bid control works as a floor that each ad set should not fall below. Google's tolerance moves in the other direction, explicitly permitting results under the target.

Bid limits on portfolio strategies cap or floor cost-per-click (CPC) bids. Tolerance instead shifts the return the whole strategy aims for.

Recent developments

On the October 15, 2026 episode of Ads Decoded, Tal Akabas, a Google Ads product manager, said promotion mode was leaving beta on Search and Performance Max, hedging the date with "I think this week". He also disclosed that a scheduled promotion turns on Smart Bidding Exploration for its duration, a detail absent from the June material, and warned that without uncapped budgets "the system will be constrained". Marvin said Exploration was rolling out to Performance Max campaigns with product feeds and coming to Shopping.

Timeline

  • March 11 to April 11, 2025 - Period of Google internal data behind the 18% and 19% Exploration figures.
  • May 21, 2025 - Google announces Smart Bidding Exploration with "flexible ROAS targets" for Search.
  • August 6, 2025 - Python client library for Google Ads API v21 published, the first version carrying target_roas_tolerance_percent_millis.
  • October 15, 2025 - Google Ads API v22 adds date segmentation for unique query cluster metrics.
  • 2025 - Google Ads Editor 2.11 adds Exploration as an opt-in for Search (dated November 6 by PPC Land, September by others).
  • May 7, 2026 - Google says Shopping and feed-based Performance Max campaigns will get Target ROAS tolerance.
  • June 15, 2026 - Exploration generally available for Performance Max without a feed; promotion mode enters beta.
  • June 23, 2026 - "Target ROAS" restored as a standalone strategy label.
  • August 17, 2026 - Budget-limited Target ROAS and Target CPA campaigns steered toward entered targets.
  • September 25, 2026 - Target ROAS edits reported blocked during active promotion windows.
  • October 15, 2026 - Google says promotion mode is leaving beta and that promotions switch on Exploration.

Summary

Who: Google sets the rules and runs the bidding; advertisers and agencies using Target ROAS or Maximize conversion value choose whether to enable a tolerance and how large it is.

What: A percentage, recommended at 10% to start and reported at up to 30%, by which Smart Bidding may undershoot a ROAS target to reach new queries, stored in the API as target_roas_tolerance_percent_millis.

When: Introduced with Smart Bidding Exploration, announced on May 21, 2025; extended to Performance Max and Shopping through 2026, and to scheduled promotion windows from June 15, 2026.

Where: Google Ads Search, Performance Max and Shopping campaigns, plus Search portfolio strategies, Google Ads Editor and the Google Ads API.

Why: Strict ROAS targets keep bidding inside proven queries; a bounded tolerance trades some efficiency for wider reach, though the evidence that it adds incremental conversions rests largely on Google's own data.