Interstitials

What it is

A full-screen advertisement displayed between content transitions, with frequency capping that protects the surrounding user experience. Maximum visual impact when the creative earns it; high abandonment risk when it does not.

The comparative framing

Interstitial is the format buyers either over-value or dismiss, often in the same conversation. Three matchups that decide which.

• Interstitial vs popunder. Both go full-screen; interstitial blocks the foreground while popunder owns the background. For app-install offers with a 5-second creative sequence and a hard CTA, interstitial structurally beats popunder on installs-per-impression by a wide margin. For offers where the user wants the foreground content they clicked toward, popunder wins because it does not punish them for arriving. In iGaming player-acquisition parallel buys across Q3 2024 in Tier-1 Europe, popunder delivered roughly 2.1x interstitial deposit volume at matched spend; for the same offer reframed as a free-to-play app install, interstitial closed the gap to within 15 percent.
• Interstitial vs in-page push. Interstitial is the high-impact moment; in-page push is the in-content consideration. The advertiser who needs both is the advertiser who has split brand and performance correctly.
• Interstitial vs video pre-roll. Both are dwell-time formats. Pre-roll lives inside the video player and trades on the user’s intent to watch; interstitial lives at content boundaries and trades on the user’s tolerance for a frequency-capped interruption. For brand campaigns with budget, pre-roll usually wins. For performance campaigns with conversion-tracking discipline, interstitial often does.

Where interstitial is the wrong call

• Verticals where dwell-time creative is not the conversion driver. Pure-click offers (utility, basic VPN trials) under-perform on interstitial relative to in-page push and banner.
• Publishers without robust frequency-cap implementations. The format is only as good as the cap; a broken cap turns every campaign into a user-experience complaint.
• Small advertisers without the creative budget to produce a 5-second sequence per GEO. The unit punishes one-creative-fits-all worse than any other format I have benchmarked.

Specs

• Pricing models: CPM and CPA. CPM is the format’s native pricing; CPA available across the major networks for verticals with clean attribution.
• Devices: Mobile and desktop, with mobile carrying most of the high-impact app-install volume.
• Geo coverage: 240+ countries claimed. Inventory concentrates in the markets with mobile-first publishers — Tier-1 plus mobile-heavy Tier-2 and Tier-3 (SEA, LATAM, parts of MENA).
• Anti-fraud: Multi-layer filtering and ML scoring on every impression. The full-screen creative makes viewability easy to measure; the harder metric is intentional engagement, which the major networks treat differently.

Methodology in the appendix.