Incremental vs total conversions
Total (attributed) conversions are every conversion a channel gets credit for under some model. Incremental conversions are the subset that would not have occurred without that channel — the causal effect measured by a holdout. The difference matters because a channel can be credited with conversions it merely rode along on. Total answers 'how many did we attribute here?'; incremental answers 'how many did this channel actually cause?'
Definitions and the gap
Total conversions are model-attributed: under last-click, data-driven, or any rule, they sum every conversion the channel is credited for. Incremental conversions are causal: the conversions present when the channel runs minus those that occur in a comparable holdout where it does not.
The gap between the two is the non-incremental credit — conversions attribution assigned to the channel that would have happened regardless.
Why both numbers exist
Attribution is cheap, continuous, and granular but cannot prove causation; incrementality is rigorous but episodic and coarse. Teams use totals for day-to-day pacing and incrementality periodically to recalibrate how much of those totals to believe.
Branded search and retargeting are the classic cases: high attributed totals, often far lower increment, because they intercept demand other channels created.
- Total = model-attributed credit for the channel
- Incremental = causal lift over a comparable holdout
- Gap = conversions that would have happened anyway
How it appears in analytics and logs
When a channel's incremental count is far below its attributed total, much of its credit reflects conversions that would have happened anyway.
Diagnostic use case
Separate a channel's attributed volume from its causal contribution before deciding whether cutting it would lose real conversions.
What WebmasterID can help detect
WebmasterID's observed first-party conversions feed both views: the attributed totals you read daily and the holdout comparisons that estimate increment.
Common mistakes
- Treating attributed totals as causal contribution.
- Cutting a channel on increment without checking assist totals.
- Comparing increment and total across different periods.
Privacy and accuracy notes
Incremental measurement uses aggregated test-vs-control comparisons, not individual tracking. Educational, not legal advice.
Related pages
- Incrementality testing: what attribution cannot tell you
Incrementality testing measures the lift a channel actually causes by withholding it from a control group and comparing outcomes. It answers the question every attribution model dodges: would this conversion have happened anyway? It is causal where attribution is merely correlational, but it requires deliberate experiment design.
- Post-impression vs post-click
Post-click attribution credits a conversion to an ad the user clicked; post-impression (view-through) attribution credits a conversion to an ad the user saw but did not click, within a window. Post-click rests on a deliberate action; post-impression rests on an ad being served and (sometimes) viewable. They measure different strengths of evidence, and mixing them without labels inflates totals.
- Baseline and incremental lift
Every conversion total contains a baseline — what would have happened without the marketing — and an incremental portion driven by it. Incremental lift is that incremental portion: conversions a campaign actually caused, over and above the baseline. Confusing the two leads to crediting marketing for sales it did not cause. This page defines baseline and incremental lift and explains how experiments estimate the split.
- Attribution analytics
Read attributed totals beside holdout-based increment.
Sources and verification notes
- Google Ads Help — About conversion liftDefines incremental conversions via test-vs-control holdouts.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.