What is incrementality?
Incrementality is the additional outcome caused by marketing that would not have happened otherwise. One way to express it is incremental conversion share: for equally sized groups, subtract control conversions from test conversions, divide by test conversions, and multiply by 100.
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How to calculate incremental conversion share
For equally sized groups, subtract control conversions from test conversions, divide by test conversions, then multiply by 100. Normalize unequal groups before using counts.
Percentages in this equation use numeric percent values: 40 means 40%.
Why incrementality matters
Platform reports count every conversion that follows an ad, including from people who would have bought anyway. Incrementality isolates the conversions your marketing truly added, so you can pay for results and not for coincidence.
It's most valuable for channels that target people already likely to buy, such as branded search and retargeting, where reported results can be much higher than the real impact.
How incrementality is measured
The standard approach is a controlled experiment. You show ads to a test group, withhold them from a similar control group, and compare conversions. Holdout tests, lift tests, and geo experiments all work this way.
The formula above assumes the two groups are the same size. If they aren't, compare conversion rates instead of raw counts.
Disclaimer
This calculator is for informational purposes only, and we don't guarantee the accuracy of its results. You're responsible for verifying any results before relying on them. See our terms of use.
Common questions
How do you calculate incrementality?
The calculator measures incremental conversion share, not every possible incrementality metric. For equally sized groups, subtract control conversions from test conversions, divide by test conversions, and multiply by 100. For 1,000 test conversions and 800 control conversions, the share is 20%. Adjust for unequal group sizes before comparing.
What is the difference between incrementality and lift?
Incrementality is the general concept of outcomes caused by marketing. This calculator expresses the incremental difference as a share of the test result; a control-relative lift calculation divides by the control result instead. State which denominator you use because terminology varies.
What are incremental conversions?
They're the extra conversions caused by marketing, found by subtracting what the control group did from what the test group did.
Why isn't attribution enough?
Attribution splits credit among conversions that already happened. It can't show which of them the ads caused, which is what incrementality tests measure.
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