In marketing, incrementality is a metric of how marketing and advertising increase desired conversion rates, such as revenue, website traffic, and profitability. It refers to growth, traffic, and revenue that can be attributed to marketing efforts.

Incrementality can point to how much a certain campaign, channel, or project affected metrics like revenue and traffic. The point of incrementality is to prove the impact of a marketing variable by isolating it. Incrementality can be measured in a few ways, including holdout tests and multivariate tests.