Definition
Incrementality refers to the additional conversions or revenue generated directly because of advertising, beyond what would have happened without the ads.
In other words, it measures the true causal impact of your campaigns in Google Ads, rather than just the conversions that were attributed to them.
How It Works
Standard attribution shows which ads were involved in a conversion.
Incrementality goes one step further and asks:
Would this conversion have happened anyway without the ad?
Incrementality is typically measured through:
- A/B testing (geo or audience split tests)
- Holdout groups (where a portion of users does not see ads)
- Conversion lift studies
- Controlled experiments
By comparing a test group (exposed to ads) with a control group (not exposed), advertisers can determine the true incremental lift.
Why It’s Important
Incrementality helps advertisers:
- Avoid overestimating campaign impact
- Prevent paying for conversions that would have happened organically
- Allocate budget more effectively
- Identify which channels truly drive growth
This is especially important for brand campaigns, remarketing, and Performance Max, where some conversions might occur without paid ads.
Example
If a campaign reports 1,000 conversions, but testing shows that 700 would have happened anyway, the true incremental impact is only 300 conversions.
That means the campaign’s real contribution is smaller than attribution reporting alone suggests.
Key Considerations
- Requires proper experimental setup.
- Works best with sufficient volume and data.
- Should be evaluated over a meaningful timeframe.
Incrementality provides a deeper understanding of advertising effectiveness by measuring real growth impact, not just attributed results.