Attribution & Conversion Counting

First-Click Attribution vs Position-Based Attribution

In short: Both models give real weight to the touch that started a customer's journey, but position-based refuses to ignore the close the way first-click does. First-click hands the entire conversion to the earliest touch and nothing else. Position-based gives that same first touch a fixed 40 percent, gives another 40 percent to the last touch, and splits the remaining 20 percent across whatever happened in between. Both were retired as selectable models in Google Ads and GA4 in 2023. Use first-click only when you need to isolate discovery in total isolation; use position-based when you want discovery recognized without pretending the close did not matter.

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

First-Click Attribution

Assigns the full conversion credit to the first recorded ad interaction in a user's path, treating discovery as the decisive moment.

The earliest touch in the conversion path takes 100 percent of the credit, which highlights channels that create demand rather than harvest it. Teams reach for it when arguing that prospecting is undervalued by default reporting. Google Ads and GA4 retired it as a selectable model in 2023, so it now lives mainly in independent analytics. Its flaw is symmetrical to last click: it ignores everything that closed the sale.

Full definition

Position-Based Attribution

Assigns forty percent each to the first and last touchpoints and splits the remaining twenty percent across everything in between.

Also called U-shaped, this model rewards the two moments most advertisers care about, discovery and close, while acknowledging the middle without letting it dominate. It fits multi-step B2B paths where an early content touch and a final branded search both clearly matter. Google Ads and GA4 retired it in 2023. The weakness is that the weights are arbitrary conventions, not estimates derived from how your customers actually behave.

Full definition

Side by side.

The differences that actually change what happens in your account.

	First-Click Attribution	Position-Based Attribution
Credit to the first touch	100 percent.	A fixed 40 percent.
Credit to the last touch	0 percent.	A fixed 40 percent.
Credit to everything in between	0 percent.	The remaining 20 percent, split across however many mid-path touches exist.
What it implicitly claims	The close was irrelevant - only discovery mattered.	Discovery and close both mattered roughly equally; the middle mattered less.
Availability today	Retired as a selectable model in Google Ads and GA4 in 2023.	Also retired as a selectable model in Google Ads and GA4 in 2023.
Sensitivity to path length	None - first touch always gets everything.	Only the middle 20 percent gets diluted by more touches; the 40/40 bookends stay fixed.
Failure mode	A campaign that closed the sale gets literally zero recognition, however decisive it was.	The fixed 40/40 split can overstate a coincidental first touch just as much as first-click does, it is just capped at 40 percent instead of 100 percent.

What actually separates them.

First-click is the extreme, single-recipient version of what position-based does more moderately - both reward the opening touch, but position-based caps that reward at 40 percent and reserves the rest for the close and the middle.

Position-based always produces at least two credited touchpoints per conversion, first and last, assuming they differ; first-click always produces exactly one, so position-based inherently gives you more channels to evaluate from the same data.

First-click completely erases the closing touch's role; position-based deliberately preserves it at an equal 40 percent weight to the opening touch, which makes position-based a meaningfully different story whenever the first and last touches are different channels.

Both were removed from Google Ads and GA4 reporting in the same 2023 change, so unlike pairs involving last-click, neither of these is a live platform setting today - both require external path reconstruction.

A channel that only ever opens journeys will show 100 percent credit under first-click and a flat 40 percent under position-based, meaning switching between the two models can cut that channel's apparent value by more than half without the channel's actual behavior changing at all.

Which one should you use?

Use First-Click Attribution when

You need to isolate the discovery touch in total isolation, with nothing else diluting the number.
You are specifically arguing that upper-funnel spend gets undervalued and want the starkest possible contrast against last-click.
You have the timestamped multi-touch data to compute it externally.
Your paths are typically short enough that first-click and position-based would barely differ anyway, so the simpler model is fine.

Use Position-Based Attribution when

You run longer paths where both the discovery touch and the closing touch are clearly different channels that both mattered.
You want to acknowledge the close without letting it erase the value of what started the journey, or vice versa.
You are building a B2B or considered-purchase attribution view where a content touch and a branded search touch both deserve recognition.
You have the ordered path data to compute it, since neither model is live in Google Ads or GA4 anymore.

Common questions.

Is position-based attribution just first-click and last-click averaged together?

Not quite - it is closer to first-click and last-click each getting a fixed 40 percent share, with the remaining 20 percent held back for whatever happened in the middle, rather than a true average of the two models' outputs. The middle touches get some recognition under position-based that they would get zero of under either first-click or last-click alone.

Why would I use position-based instead of first-click if I care about discovery?

First-click's 100 percent credit to the opening touch can make it look like nothing else in the path mattered, which is rarely true for a multi-step purchase; position-based keeps the discovery touch meaningfully weighted at 40 percent while still acknowledging that something else, the close, also happened and also deserves credit.

Are either of these models available in Google Ads today?

No, Google Ads and GA4 removed both first-click and position-based as selectable models in 2023, along with linear and time-decay, leaving data-driven attribution as the default and last-click as the remaining rule-based option. To see either model now you would need to export path-level data and calculate it yourself.

What happens under position-based if the first and last touch are the same channel?

That channel simply collects both 40 percent shares, effectively 80 percent of the credit, while the remaining 20 percent still gets split across any middle touches. It is mathematically identical to running the rule on any other path - the model does not special-case a repeated channel.

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