An attribution window is the time period after an ad click or impression during which an install will still be credited to that ad. If your click-through attribution window is 7 days and a user clicks an ad on day 1 then installs on day 5, the install gets credited. If they install on day 10, it doesn't. The window defines the boundary of "this ad caused this install" — anything outside is treated as organic or attributed to a different source.
Two flavors that matter
- Click-through window: time between ad click and install. Typical: 7 days (Meta default), 30 days (legacy default for Apple Search Ads and some MMPs). Longer windows credit more installs but include more "click happened then user did unrelated things" noise.
- View-through window: time between ad impression (no click) and install. Typical: 1-24 hours. View-through attribution is weaker signal than click-through — the user saw the ad but didn't engage with it, then installed for some reason that may or may not be the ad.
The trade-off is signal vs noise
- Short windows (1-day click, 1-hour view-through): strict, low false-positive rate, but miss delayed conversions (the user who saw the ad, thought about it for 5 days, then installed).
- Long windows (30-day click, 24-hour view-through): generous, credit more delayed conversions, but include installs that were probably driven by other factors (the user clicked the ad weeks ago and would have installed anyway).
Mature UA programs run multiple window configurations side-by-side in analytics to understand the spread, then choose a "production" window for ad-platform optimization based on what aligns with realistic user-decision timeframes.
SKAN constrains iOS attribution windows. SKAdNetwork 4 fires postbacks at three windows after install: 0-2 days, 3-7 days, 8-35 days. These are defined by Apple, not by the advertiser. The 35-day overall maximum is shorter than the legacy 30-day click-through Apple Search Ads window (functionally similar), but the multi-window structure changes how you think about it — you see early-funnel signal in window 1, mid-engagement signal in window 2, and monetization signal in window 3, but they're all anchored from install date, not click date.
Network defaults differ — normalize before comparing**:
- Meta: 7-day click + 1-day view-through default (configurable).
- TikTok: 7-day click + 1-day view-through default.
- Google Ads (UAC): 30-day click default.
- Apple Search Ads: 30-day click.
- AppLovin / ironSource: typically 7 days click, configurable.
When you compare cross-network attribution counts, you'll find a 30-day window network credits more installs than a 7-day window network even on identical traffic. Always normalize to the same window before comparing.