Why is the audience count in my Customer Journey different from the number shown in the Segment calculator?

A difference between the audience size shown in a Customer Journey and the size shown for the same segment is expected. The two numbers count different things, and the segment view itself reports more than one figure.

What the segment view shows

After you calculate a segment, the summary card Included in segment shows both:

• Unique users — the number of distinct users (User IDs) matching the conditions.
• Devices — counts broken down by channel (mobile, web, email, SMS, WhatsApp, Line). One user can contribute several devices here.

Make sure you are comparing against Unique users and not against a device or channel count.

What the Customer Journey shows

A journey enrols users, so its audience figure is a user count. Even against Unique users it can still differ, for three reasons:

• The number is a snapshot. The segment card shows the size at the last calculation ("Calculated" date). Click Update segment size to recalculate before comparing.
• Entry scope. An Audience-based entry can be set to Existing users only, Existing + new users or New users only, which changes how many of the matching users actually enter.
• Reachability and delivery rules. Users can be filtered later in the flow by a Reachability check, frequency capping, the silence period or the global control group.

If the two figures still diverge sharply after a fresh recalculation, check the entry scope first — that is the most common explanation.