Bidding Strategies

Target CPA vs Target Impression Share: Efficiency or Visibility

In short: Target CPA buys conversions at a cost you name and ignores where your ad ranks. Target Impression Share buys position and share of impressions and ignores whether anything converts. They optimize toward incompatible goals, which is why the second is almost entirely a brand-defense tool rather than a performance one.

By the AdFlint research team · Fact-checked against current Google and Meta platform behavior · Last reviewed July 2026

Target CPA

Bids automatically toward a chosen average cost per conversion, letting individual conversions land above or below that number.

It now lives as a target field inside Maximize Conversions rather than a standalone strategy. Google bids up on auctions it expects to convert near your target and backs off elsewhere, so a target far below recent actual CPA simply throttles volume. Set it close to what the account already achieves, then move it in increments and let the learning period settle before judging the outcome.

Full definition

Target Impression Share

Sets bids to reach a chosen share of impressions at a chosen page position, bounded by a maximum CPC ceiling you define.

You pick absolute top, top, or anywhere on the results page plus a percentage, and Google bids whatever is needed up to your ceiling. It is a visibility strategy, used mostly for brand defense and specific competitive terms where presence matters more than efficiency. The mistake is running it on non-brand terms with a high ceiling, since it buys position whether or not those impressions ever convert.

Full definition

Side by side.

The differences that actually change what happens in your account.

	Target CPA	Target Impression Share
What you name	An average cost per conversion.	A page position and a percentage of impressions.
What it optimizes	Conversion efficiency.	Visibility.
Cost guardrail	The target itself, plus the budget.	A maximum CPC ceiling you have to set yourself.
Uses conversion data	Required - it is the whole basis of bidding.	Not used by the strategy at all.
Where it belongs	Non-brand and remarketing campaigns carrying the performance load.	Brand terms and a small set of must-win competitive terms.
Failure mode	Target below achievable CPA, which throttles delivery.	Loose ceiling on non-brand terms, buying impressions that never convert.

What actually separates them.

tCPA prices auctions by predicted conversion; tIS prices them by whatever reaching your chosen position costs, up to your ceiling.

tIS ignores conversion data entirely, so it keeps buying position on terms that have never produced a sale.

The max CPC ceiling is the only cost control on tIS, and it is the setting most often left too high.

tCPA under-spends when the target is tight; tIS overspends quickly when the ceiling is loose.

On brand terms tIS is defensible because conversion rate is already high and the goal is denying a competitor the slot; on non-brand it usually is not.

Which one should you use?

Use Target CPA when

Non-brand campaigns judged on cost per lead or cost per sale.
Steady conversion volume and tracking you have verified.
Budget should follow efficiency rather than position.
You are scaling spend and want unit cost to stay anchored.

Use Target Impression Share when

Brand terms where a competitor is bidding on your name and absence is expensive.
A small set of high-stakes commercial terms where being missing loses the deal.
Launch moments where share of voice is genuinely the objective.
You have set a firm max CPC ceiling and will monitor spend closely.

Common questions.

Can I use Target Impression Share on non-brand keywords?

You can, and it usually goes badly. The strategy buys position regardless of conversion likelihood, so on broad commercial terms it spends against impressions that were never going to pay back. If non-brand visibility matters, express it through budget and coverage rather than handing the bidder a position target.

Does Target Impression Share improve Quality Score?

Not directly. It bids to reach a position; it does not improve ad relevance, expected CTR, or landing page experience, which are what drive Quality Score. Paying for position can mask a weak Quality Score for a while, at a price, but the underlying diagnostics do not move because of a bid strategy.

What should the max CPC ceiling be?

Set it from what the term is worth to you, not from what it currently costs. Because the strategy bids up to the ceiling whenever position demands it, the ceiling is your real spend control on that campaign. Revisit it after competitive shifts, since a stale ceiling either stops working or starts overpaying.

Or stop choosing between them.

AdFlint picks the setting, writes the ads, and keeps optimizing inside the Google and Meta accounts you already own.

Try AdFlint free See how it works

Related comparisons

All comparisons