What a bid strategy actually controls
Each search triggers an auction. Whether your ad shows, and where, depends on Ad Rank: your bid, the quality of your ad and landing page, minimum thresholds, the competitiveness of the auction, the context of the search and the expected impact of your assets. The bid strategy is the part of that equation you choose: the rules by which your bid is formed.
There are two broad routes. With manual bidding you set a maximum cost per click per keyword or ad group. With automated bidding you give Google a goal and it sets a bid for each auction. The automated strategies that optimise for conversions or conversion value are called Smart Bidding; Google describes them as auction-time bidding, using signals such as device, location, time and language that no person could weigh search by search. How auction outcomes turn into your invoice is covered in our guide to Google Ads cost.
CPC, CPA and ROAS: the measures behind every strategy
Cost per click (CPC)
What you pay for one click. You often pay less than your maximum, typically what is needed to beat the advertiser below you. There is no meaningful general average CPC: it varies by sector, keyword, region and moment, and figures quoted online say little about your market.
Cost per acquisition (CPA)
What one conversion costs: an enquiry, a booking, an order. Divide ad cost by conversions. With Target CPA you ask Google to win as many conversions as possible at around that average cost.
Return on ad spend (ROAS)
Conversion value divided by ad cost. If £1,000 of spend brings £4,000 in tracked revenue, ROAS is 400%. Target ROAS steers towards that ratio. Remember that ROAS measures revenue, not profit: a retailer on thin margins can show a healthy ROAS and still lose money, which is why some advertisers feed gross profit rather than revenue into conversion values.
The bidding strategies in Google Ads at a glance
Google groups strategies by goal: conversions, clicks or visibility. Its own article on choosing a bid strategy based on your goals is the reference. For most businesses that want leads or sales, the choice lies among the first four rows.
| Strategy | Optimises for | Fits when | Precondition |
|---|---|---|---|
| Maximise conversions | As many conversions as possible within budget | Tracking is sound and you want to build volume | Reliable conversion tracking |
| Target CPA | Conversions at an average cost you set | You know what a lead or sale may cost | Steady conversion volume |
| Maximise conversion value | As much value as possible within budget | Conversions differ in value, as in ecommerce | Accurate values per conversion |
| Target ROAS | Value relative to ad spend | You know your margins and want to protect return | Stable value data over time |
| Maximise clicks | As many clicks as possible within budget | A new campaign without conversion data | A maximum CPC limit is wise |
| Manual CPC | A fixed maximum per click that you set | Small accounts, tight control or testing | Time to adjust bids weekly |
| Target impression share | Visibility in a chosen position | Brand protection as a deliberate aim | A clear bid ceiling |
Manual CPC or Smart Bidding?
Manual CPC gives direct control. You see exactly what you are prepared to pay per keyword and can react quickly. That helps when conversions are scarce, in a small niche, or while you learn which keywords work. Its limit is that you bid per keyword while every search differs: someone searching on a phone in your area on a weekday evening may be worth far more than a desktop search from the other end of the country. Manual bidding weighs that only crudely.
Smart Bidding weighs it in every auction, but you see less and steer indirectly, through your goal, budget, conversion settings and the values you assign. That only works if those inputs are right. If every tap on a phone number counts as a conversion, Google learns to buy taps on phone numbers, whether or not a client is behind them.
For years there was a middle option, Enhanced CPC, which let Google raise or lower manual bids. Google states that from the week of 24 March 2025 Enhanced CPC is no longer available for Search and Display campaigns; campaigns not moved in time now effectively run on manual CPC. Older guides that recommend it are out of date.
Setting a Target CPA in Google Ads
A target is an instruction, not a wish. Set it too tight and Google bids so cautiously that impressions dry up; too loose and you buy conversions you cannot afford. Google's article on Target CPA bidding explains the mechanics. The number itself should come from your business.
- Start with client value. Average margin per order, or the value of a new client over a sensible period.
- Translate it to a lead. If five enquiries produce one client, an enquiry can cost at most a fifth of what a client is worth to you, less the margin you want to keep.
- Check current performance. Set the first target close to what the account has actually achieved recently. A target far below today's CPA chokes the campaign.
- Adjust in small steps. Large jumps force the strategy to recalibrate.
Labels are shifting: Google notes that from June 2026 'Maximise conversions with a Target CPA' is being renamed 'Target CPA', and the value equivalent 'Target ROAS'. The underlying bidding behaviour stays the same, so do not be thrown if your account shows either name.
Target ROAS for online shops
Target ROAS is often the natural destination for ecommerce, provided conversion values are right: the order value without VAT and delivery if that is how you assess margin, consistent across Shopping, Performance Max and Search. Set the target from margins rather than from a figure you heard elsewhere, and accept that a higher target usually means less volume. For catalogue businesses, feed quality and product margins matter as much as the bid strategy; that is the core of our Google Shopping agency work.
The learning period: why patience pays after a change
When you switch to a new Smart Bidding strategy, or change the target, budget or conversion settings significantly, the system needs time to recalibrate. Performance swings more than usual in that period. What not to do:
- draw conclusions after two days and switch back;
- make several large changes at once, so you cannot tell what had an effect;
- move the target every few days.
How long it takes depends mainly on conversion volume and how long customers think before converting. An account with daily conversions settles faster than one with a few enquiries a week. Google recommends evaluating Smart Bidding over periods with at least 30 conversions, such as a month or longer, or 50 conversions for Target ROAS. Judge in weeks, not days.
When to move to a different bid strategy
Most accounts follow a recognisable path. It is not a rule, but it is a sensible order.
- Launch, no conversion data. Manual CPC, or Maximise clicks with a maximum CPC, so budget does not vanish on expensive clicks.
- First conversions. Tracking is tested and conversions arrive regularly: move to Maximise conversions.
- Stable volume. You know what a conversion costs and what it may cost: add a Target CPA close to actual performance.
- Different values. Some conversions are worth much more than others: pass values and move to Maximise conversion value, later perhaps with a Target ROAS.
Avoid switching while a learning period is running, just after tracking changes or in the middle of a seasonal peak. Bidding and keyword choice are closely linked: broad match gives Smart Bidding more room, which makes search term reviews and negatives more important. See our guide to Google Ads keywords.
No strategy works without sound measurement
Smart Bidding optimises for whatever you label a conversion, so tracking is the foundation.
- Primary conversions should be genuine business outcomes: an enquiry, an order, a booked appointment. Page views do not belong among them.
- Consent. UK GDPR and PECR apply to tracking cookies, and Google's consent requirements cover UK users. Without a proper consent mode set-up you lose part of your conversions and bidding works from a distorted picture.
- Lead quality. A form submission says nothing about revenue. Importing CRM outcomes back into Google Ads teaches the system which enquiries became clients.
Our conversion tracking service builds that foundation. Typical mistakes: Smart Bidding on unreliable data, a target CPA plucked from a benchmark, a target higher than the daily budget so the campaign barely learns, and confusing revenue with profit. If you want to hand over bidding, tracking and weekly optimisation, PPC management is the natural next step; for an outside view first, a Google Ads audit reviews structure, tracking and bid settings.