Why Meta reach should not be added across rows
Avoid double-counting people when combining reach across ads, days or overlapping audiences.
Reach concerns unique exposure within a defined scope. The same person can appear in several daily or ad-level rows, so those rows are not independent populations. Ask the source for the aggregate scope you need instead of building it by addition.
Work through it, step by step.
Write down the scope of the desired total: account, campaign or ad over a specific period. Keep that scope distinct from the detailed breakdown.
Request the aggregate reach at that level where supported. Retain daily or ad rows for pattern analysis rather than treating their sum as a unique audience.
When aggregating compatible additive measures, keep reach outside that calculation. Label any unavailable whole-period reach as unavailable.
Make it concrete.
An ad reaches 100 people on Monday and 100 on Tuesday. If 60 people appear on both days, the combined audience is 140, not 200.
What to keep in mind.
The overlap cannot generally be recovered from the two daily totals alone. A spreadsheet formula cannot deduplicate people it cannot identify.
Your next useful step.
Use whole-period provider reach and retain the breakdown separately. Apply the same caution when interpreting frequency derived from impressions and unique reach.
Working with this in Liftaven
Record the ad account, reporting level and attribution settings before comparing results. Delivery and conversion reports can be revised as events arrive. Liftaven reads Meta advertising data; changes to campaigns, creatives, audiences and tracking are made in Meta tools.
Explore the workspaceSources & context
This note combines original practical guidance with the reporting references below. Follow provider documentation for current definitions and availability; suggested investigations are not guarantees of a particular result.