How Smart Bidding Works and What It Can't Fix

Smart Bidding is Google’s group of bid strategies that set a separate bid for every auction. Each bid rests on a prediction of whether the click will convert and, for value strategies, what the conversion will be worth. In a store account, it decides which auctions you enter and what you pay per click, optimising for the conversions you mark as primary and their values. It cannot raise your site’s conversion rate or average order value, and it learns from every order amount it receives, right or wrong.

Which bid strategies count as Smart Bidding

According to Google Ads Help (About Smart Bidding), Smart Bidding covers bid strategies that use Google AI to bid in every auction. They optimise for conversions or for conversion value, the amount each conversion is reported to be worth. Google names four such strategies. Two count orders (conversion strategies), and two count money (value strategies).

Since June 2026, Search campaigns list Target CPA and Target ROAS as standalone strategies. Before that, they appeared as “Maximize conversions with a Target CPA” and “Maximize conversion value with a Target ROAS”. Google says only the labels changed and the strategies work the same way (Changes to how Smart Bidding strategies are organized for Search campaigns).

Performance Max runs on Smart Bidding alone. Its only options are Maximize conversions with an optional target CPA, or Maximize conversion value with an optional target ROAS (Create a Performance Max campaign, Google Ads API documentation). Google stopped offering Enhanced CPC in Search and Display campaigns in the week of 31 March 2025. Campaigns left on it now run on manual CPC (Your guide to Smart Bidding).

Our guide to bidding strategies for online stores covers which of the four fits your store, given how many conversions it gets a month. This article covers what all four share: what they learn from, and where their reach ends.

How Smart Bidding sets a bid in each auction

With manual bidding, you set one bid for a keyword or a group of products, and it stays until you change it. Smart Bidding sets a bid for each auction at the moment it happens. Google calls this auction-time bidding.

For every auction, a value strategy reads the context of the search and predicts two things: the chance that this click converts and the likely value of the conversion. Then it sets a bid that fits your target or your budget. A conversion strategy predicts only the chance of a conversion. That is how Google’s guide to automated bidding, Setting Smarter Search Bids, describes the calculation (pp. 11–12).

Google Ads Help (About Smart Bidding) lists the signals Smart Bidding reads at auction time. Among them:

• device, physical location and location intent, weekday and time of day;
• remarketing lists, browser, operating system and interface language;
• the actual search query, in Search and Shopping;
• for Shopping: product attributes such as price, brand, condition and category, how your price compares with other advertisers in the same auctions, and seasonal trends.

Smart Bidding weighs how signals combine, not only each signal on its own. In the Shopping part of that list, it reads your price against other advertisers’ prices. Changing your price is up to you.

Smart Bidding also allows for late conversions. It gives more weight to recent data and accounts for the usual delay between a click and a conversion, known as the conversion cycle. After a change, Google advises judging performance only once one or two conversion cycles have passed (Setting Smarter Search Bids, p. 16).

What Smart Bidding learns from: your primary conversions and their values

Smart Bidding needs conversion tracking switched on. Its predictions are only as good as the conversions behind them. Two settings decide what those conversions are.

Which actions count. Bidding uses only the conversion actions set as primary. The interface marks them “Primary action used for bidding optimization”. Secondary actions still appear in the All conv. column, but bidding uses them only if you add them to a custom goal (Conversion goals, Google Ads API documentation).

What each conversion is worth. For a store, the conversion value should be the order amount your site sends with each purchase. If the tag sends no value or an invalid one, or you set the action to always use a default, Google records the default value instead (ValueSettings, Google Ads API reference).

The second setting matters most for value-based bidding. Maximize conversion value may bid higher in auctions likely to bring more value, so it needs values that differ the way your real orders differ. For this strategy, Google requires conversion tracking with transaction-specific values: each order sends its own amount (About Maximize conversion value bidding). Before you switch to a value strategy, Google asks for conversions with two or more different values (Your guide to Smart Bidding).

Bidding works on cost per click; the rest of ROAS comes after the click

ROAS breaks into three numbers. Bidding sets one of them directly:

• Cost per click — what you pay for one click. This is where the bid works.
• Conversion rate — the share of clicks that end in an order. Smart Bidding affects it in one way: it bids more for clicks it expects to convert.
• Average order value — what one order brings on average. It depends on your prices, basket size and product mix.

ROAS = conversion rate × average order value ÷ cost per click. This is arithmetic: revenue per click divided by cost per click.

Example store, not client data.

A tableware shop gets 8,000 clicks a month at an average cost per click of 5, so it spends 40,000. Of those clicks, 3.75% become orders: 300 orders with an average value of 600, or 180,000 in revenue. ROAS = 3.75% × 600 ÷ 5 = 4.5.

Now a bestseller goes out of stock and the conversion rate drops to 3.0%. ROAS falls to 3.0% × 600 ÷ 5 = 3.6. To get back to 4.5 through bidding alone, cost per click would have to fall from 5 to 4, a fifth less. And the cheaper clicks would have to convert just as well.

Prices, stock, delivery terms and checkout speed are up to you. They sit after the click, and so does most of the formula.

In our data, ROAS moves with conversion rate and average order value rather than cost per click

We took 1,360 month-to-month changes in store accounts (GetProfit data, June 2025 – June 2026). For each one, we checked which part of the ROAS formula moved together with ROAS: conversion rate, average order value or cost per click. We measured each change against the median change across all stores in the same month, so seasons and platform-wide shifts cancel out.

The rank correlation (rho) with a change in ROAS was +0.527 for conversion rate, +0.540 for average order value and −0.100 for cost per click. Rho shows how closely two numbers move together: the further from zero, the closer the link. A minus sign means they move in opposite directions. The months with the largest swings show the same split:

Medians of month-to-month changes, each measured against the same-month median across all stores. GetProfit data, June 2025 – June 2026.

Cost per click moves little even when spend moves a lot. In the 155 months when stores raised spend by more than 70% against other stores, the median cost per click rose 9.2% (same data and method). The same holds across stores. Among 114 stores with at least eight months of data, a store’s ROAS level goes together with revenue per click (rho +0.633) far more than with cost per click (rho −0.221).

This is an observation, not an experiment. It cannot show how much of a swing in conversion rate came from the clicks Smart Bidding chose and how much from the site, prices or stock. We do not see what happens on stores’ sites. ROAS here is revenue reported in Google Ads divided by spend, not profit.

In practice: if ROAS dropped and cost per click barely moved, the formula points to conversion rate or average order value. Work out what to fix after the click before you change targets.

Wrong conversion data: when tracking works but Smart Bidding learns the wrong thing

Smart Bidding learns from every primary conversion exactly as Google receives it. The usual check asks whether data arrives at all. The cases in the table pass that check and still teach bidding the wrong thing. Setting up tracking is a separate job; our guide to conversion tracking for online stores covers it.

Example store, not client data.

A tableware shop has 300 real orders worth 180,000 on 40,000 of spend:

• Default value. If the purchase action always sends a default value of 100, Google sees 30,000 in conversion value and a ROAS of 0.75 instead of 4.5. Against a Target ROAS of 450% (4.5), the campaign looks far below target. Google’s guide to automated bidding says a strategy trending below target ROAS may lower bids until it reaches the target (Setting Smarter Search Bids, p. 12).
• Double count. If a Google Ads purchase tag and an imported GA4 purchase are both primary, each order can count twice. The account then shows up to 600 orders, 360,000 in conversion value and a ROAS of 9.0.
• One outlier. A single test order worth 30 times a typical order of 600 adds 18,000. That one conversion equals a tenth of the month’s real revenue.

A broken tag does similar damage over time. If tracking stopped for a few days, those days teach Smart Bidding that clicks stopped converting. Google’s data exclusions tell Smart Bidding to ignore data from dates with conversion tracking issues. Google also warns that using them often or for long periods can hurt performance (Create data exclusions).

How the GetProfit portal checks what Smart Bidding learns from

The Conversion check in the GetProfit portal looks at what your campaigns learn from. It runs four checks:

• the event: a purchase or a lead, not a page view;
• the value: real order amounts or one repeated number;
• duplicate goals that count the same order;
• amounts many times larger than your average order value.

The portal treats a conversion as anomalous when the value recorded for a product on one day is more than 30 times the account’s median order value. It lists each one with its date, campaign and product. For a product campaign with at least 10 conversions, it also flags an average conversion value below 0.30× or above 8× the median order value.

Where the value can’t be trusted, the portal hides ROAS and counts by the number of orders and the cost of one order instead. The account score gets a trust adjustment that explains why it is lower.

GetProfit’s methodology treats a value strategy (Target ROAS or Maximize conversion value) running on a default value as a settings conflict. The fix: send the real order amount, or move the campaign to Target CPA or Maximize conversions until you do.

What your ads are really learning on. An order counted twice. An amount substituted for the real one. A payment several times larger than your usual basket. The portal checks what stands behind them. The portal changes nothing without your consent.

Check your conversions →

Does Smart Bidding work?

Smart Bidding does what it is built to do: it prices each click against the goal and the data you give it. Whether that raises revenue depends on two things outside it. Are the conversions it learns from true? And do the clicks it buys land on an offer that sells?

Judge it over enough time. Google recommends measuring Smart Bidding over a period with at least 30 conversions, such as a month or longer, and 50 for Target ROAS (About Smart Bidding).

In our data, the median store’s ROAS sits a typical 16% away from its own median from month to month. The median ratio of the best month’s ROAS to the worst is 3.1 (GetProfit data, 110 stores with at least eight months, June 2025 – June 2026). So judge a weak month against that normal swing before you blame the strategy.

What to check before you change the bid strategy

1. Confirm what the campaign learns from. Find the actions marked “Primary action used for bidding optimization”. For a store, that should be the paid order, not a page view, an add to cart or a checkout start.
2. Check that the value varies. Compare conversion value per conversion with your real average order value. If every conversion shows the same value, Google is getting one fixed number instead of the order amount.
3. Look for two goals counting one order. A Google Ads purchase tag and an imported GA4 purchase, both set as primary, count the same order twice.
4. Look for outliers. A conversion worth dozens of times your typical order (a test, a wholesale order, a checkout glitch) teaches Smart Bidding about a buyer who does not exist.
5. Exclude broken days. After a tracking outage, add a data exclusion for those dates so Smart Bidding ignores them.
6. Bid on value only when you trust it. Until the real amount arrives, run Target CPA or Maximize conversions. After you fix the value, Google recommends waiting one or two conversion cycles in Search and Shopping campaigns before switching to Maximize conversion value (About Maximize conversion value bidding).
7. Split a ROAS change into its parts. Check whether conversion rate, average order value or cost per click moved. If cost per click is flat, work on prices, stock and the site before you touch the target.
8. Give a change time. Judge it after one or two conversion cycles and against your normal monthly swing. For a planned sale of one to seven days, a seasonality adjustment tells Smart Bidding to expect a different conversion rate. Google says it may not work as well beyond 14 days (Create seasonality adjustments).

Sources

• About Smart Bidding — Google Ads Help: definition, the four strategies, auction-time signals including Shopping-only ones, conversion tracking required, evaluation over at least 30 conversions (50 for Target ROAS). Checked 2 October 2026.
• Your guide to Smart Bidding — Google Ads Help: Enhanced CPC unavailable in Search and Display since the week of 31 March 2025; two or more different values before switching to value bidding. Checked 2 October 2026.
• About Maximize conversion value bidding — Google Ads Help: transaction-specific values required; may bid higher in auctions with greater value; wait one or two conversion cycles after changing how value is reported. Checked 2 October 2026.
• Changes to how Smart Bidding strategies are organized for Search campaigns — Google Ads Help: June 2026 relabelling of Target CPA and Target ROAS; strategies work the same way. Checked 2 October 2026.
• Updates to Smart Bidding Strategy Naming and Organization in Google Ads — Google Ads Developer Blog, 16 June 2026: the same relabelling; bidding behaviour unchanged. Checked 2 October 2026.
• Setting Smarter Search Bids: Inside automated bidding with Google Ads — Google’s 2021 guide to automated bidding: prediction of conversion likelihood and value per auction, lower bids when below target ROAS, weighting of recent data, judging after one or two conversion cycles. Checked 2 October 2026.
• Create a Performance Max campaign — Performance Max supports only Maximize conversions (optional target CPA) and Maximize conversion value (optional target ROAS). Checked 2 October 2026.
• Bid strategy types — Enhanced CPC deprecated for Search and Display campaigns. Checked 2 October 2026.
• Conversion goals — primary actions are used for bidding, secondary actions are not unless added to a custom goal. Checked 2 October 2026.
• ValueSettings — when Google uses the default conversion value. Checked 2 October 2026.
• Create data exclusions — data exclusions tell Smart Bidding to ignore dates with tracking issues; frequent or long use can hurt performance. Checked 2 October 2026.
• Create seasonality adjustments — adjustments for short events of 1–7 days; may not work as well beyond 14 days. Checked 2 October 2026.
• GetProfit data: 1,360 store-months, June 2025 – June 2026 — which parts of ROAS move with it; 155 months with spend raised more than 70% against other stores — change in cost per click; 114 stores with at least eight months — ROAS against revenue per click and cost per click; 110 stores — month-to-month ROAS swing.
• GetProfit portal methodology — anomalous conversion values (more than 30× the median order; campaign average below 0.30× or above 8× from 10 conversions) and the rule for value strategies on a default value.