A reinstall is what happens when a user downloads an app they had previously installed and then removed. To the app store it can look like any other download, but for measurement it's a fundamentally different event from a true new install — the person is a returning user, not net-new acquisition. Getting this distinction right is essential for clean UAGlossaryPaid UA (Paid User Acquisition)Mobile app user acquisition via paid advertising channels — Meta, TikTok, Google, AppLovin, ironSource, and other ad networks. economics.
How attribution handles reinstalls
MMPs recognize a returning device/user and classify the event as a reinstall rather than a new install. They then apply reattribution logic: if a re-engagementGlossaryRe-EngagementMarketing activity aimed at bringing lapsed users back to the app — through push, email, retargeting ads, deep-linked notifications. or retargetingGlossaryRetargetingPaid advertising targeted at users who already installed your app — typically aimed at re-engaging lapsed users or driving specific in-app actions. campaign touched the user within a defined reattribution window before the reinstall, that campaign can be credited with the win-back — distinct from new-user [[install-attribution]]. This keeps "new users acquired" and "lapsed users won back" as separate lines rather than conflating them.
Why the distinction matters for economics: if reinstalls are silently bucketed as new installs, your acquisition volume looks bigger and your CACGlossaryCAC (Customer Acquisition Cost)The total cost of acquiring one customer — paid ads PLUS non-ad acquisition costs (SEO, content, sales, partnerships) divided by acquired customers. looks better than reality — you're partly paying to re-acquire users you already had. Mature programs report new installs and reinstalls separately, attribute win-backs to [[re-engagement]] / retargeting rather than acquisition, and treat a reinstall as a positive [[retentionGlossaryRetention (D1 / D7 / D30)The percentage of users from a cohort who return to the app N days after install. D1 = day-1 retention, D7 = 7-day, D30 = 30-day. The single most important non-reven...]]-recovery signal in its own right. Note that post-[[attGlossaryApp Tracking Transparency (ATT)Apple's iOS 14.5+ framework requiring apps to display a system prompt and obtain user consent before accessing the IDFA or tracking the user across other apps and we...]], detecting reinstalls on iOS is harder without the IDFAGlossaryIdentifier for Advertisers (IDFA)Apple's per-device advertising identifier — historically used for deterministic ad attribution, now only available when the user explicitly opts in via App Tracking..., so reattribution leans on SKAdNetworkGlossarySKAdNetwork (SKAN)Apple's privacy-preserving attribution framework for iOS — returns install credit to ad networks with a deliberate delay and aggregation, without exposing any device... and first-party signals.
