Free tool
How Google Ads Smart Bidding Works
With Smart Bidding, Google Ads sets your bid at every search, based on the conversion chance it predicts. Set your target CPA or target ROAS: your bid line turns, and the search profiles you win change colour.
At Google Ads, Smart Bidding optimises for conversions or conversion value in every auction. With Target CPA, Google Ads uses your target to set a bid based on the likelihood of the ad to convert. Some conversions may cost more than your target and some may cost less, but altogether, Google Ads will try to keep your cost per conversion equal to your target CPA.
- Won, costs less than your target
- Won, costs more than your target
- Lost
Profile 37
Mobile · Night · Distant location · Already visited your site
- Predicted chance
- 2.7%
- Your bid
- €0.87
- Price to beat
- €0.87
- Cost per conversion
- €32.48
Won: it costs more than your target, offset by the cheaper profiles.
Hover or tap a profile to see its bid.
Set your target
Predicted conversions
17
Average CPA
€21.58
26 profiles won out of 40 · spend €356
Of the profiles you win, 16 cost more than your target and 10 less: on average, a conversion costs you €21.58.
What Google reads at every auction
- Device
- mobile, desktop or tablet.
- Location
- the city the person is in.
- Weekday and time
- local time and day of the week.
- Remarketing list
- the person already visited your site, and how recently.
And other signals, exclusive to Smart Bidding.
Simplified model, example figures: each point is a search profile, a combination of signals, with its predicted conversion chance and the price to beat to win the click. Your bid is proportional to the predicted conversion chance (or to the predicted value of a click with Target ROAS), and its coefficient is set so that the average matches your target: some profiles you win cost more than your target, others less. Google does not publish its formula, and the budget is not simulated here. Google also explains these differences by factors outside its control, like changes to your website or ads and increased competition, and by an actual conversion rate that can be lower or higher than the predicted one. Google Ads Help: Target CPA, Target ROAS, Smart Bidding.
Is Your Target CPA Set At The Right Level?
A target that’s too low gives up clicks that would have converted; one that’s too high pays more for conversions than they bring you. Your conversion history and your margins tell where to set it.
20 minutes · No commitment · 100% confidential
How To Read The Simulator
Bid = coefficient × predicted conversion chance (simplified model, Google does not publish its formula)
Each point is a search profile: a combination of signals (device, time, location, a past visit to your site), with its predicted conversion chance and the price to beat to win the click. Every point under the “Your bid” line is won. Hover one to see its bid.
The two lines show Google’s sentence: some conversions cost more than your target and some cost less. In the example, at a €22 target CPA, your campaign wins 26 profiles out of 40: 16 cost more than your target, 10 less, and the average stays at €21.58.
What Changes With Your Target
- A target CPA that’s too low: Google says it may cause you to forgo clicks that could result in conversions, so fewer conversions in total.
- A higher target: your campaign wins more profiles, including some that cost more than your target, and the average cost moves up towards the target.
- Target ROAS: the average conversion value you want for each euro you spend. Google bids higher when a search is likely to generate a high-value conversion, and a target that’s too high limits your traffic.
- The signals: device, location, weekday and time, remarketing list, and other signals exclusive to Smart Bidding, read at the moment of each auction.
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Théo MaupiléFreelance Paid Media
Google PartnerSuperMalter
