Ad Format Selection Guide

Which ad format should you use, where, and when? This guide breaks down every mobile ad format — banner, interstitial, rewarded, native, app open, and rewarded interstitial — with concrete guidance on when each one makes sense and when it doesn’t.

The Quick Answer

Most apps should use 2–3 formats together. The combination matters more than any single format.

Banner Ads

What They Are

Small rectangular ads (320×50 or 300×250) that sit at the top or bottom of the screen while the user interacts with your app. They’re always visible and refresh automatically every 30–60 seconds.

When to Use Banners

• Apps with long session times where a persistent ad doesn’t disrupt the experience
• Utility apps (calculators, weather, file managers) where full-screen ads would feel aggressive
• News and content apps where users scroll through content
• As baseline revenue alongside higher-eCPM formats (interstitials, rewarded)

When NOT to Use Banners

• Games with immersive UI — a banner during gameplay breaks immersion
• Apps with minimal screen space — if the banner covers important content or controls
• As your only format — banner eCPMs are too low to be your sole revenue source

Placement Tips

• Bottom of screen performs better than top in most apps (less interference with navigation)
• Hide during critical interactions — if the user is filling out a form or in a checkout flow, remove the banner
• Use adaptive banners that resize to the device width rather than fixed 320×50
• Don’t stack banners — one at a time, always

Revenue Expectations

Banners generate the lowest eCPM of any format but the highest impression volume. They’re a background revenue stream, not a primary monetization tool.

Interstitial Ads

What They Are

Full-screen ads that cover the entire interface. They appear at transition points and require the user to either engage with the ad or dismiss it. Available as static images, video, or interactive/playable formats.

When to Use Interstitials

• Between levels in a game
• After completing a task (saving a file, finishing an article, posting content)
• Screen transitions where the user expects a brief pause
• Apps with clear content units — between articles, recipes, workouts, etc.

When NOT to Use Interstitials

• Mid-action — never interrupt a user while they’re doing something
• On app launch — use app open ads instead (designed for that moment)
• Back-to-back — showing two interstitials in a row feels punishing
• During onboarding — let new users experience your app before showing full-screen ads

Placement Tips

• Frequency cap at 1 per 2–3 minutes of active use — more aggressive than this and retention drops
• Skip the first occurrence — don’t show an interstitial after the user’s very first level or action
• Pre-load early — load the next interstitial immediately after showing the current one
• Show a brief “ad loading” transition if the ad isn’t ready — never show a frozen screen

Revenue Expectations

Interstitials are a strong revenue driver — 5–10x the eCPM of banners. They’re the workhorse format for most games and content apps. The key is frequency discipline.

Rewarded Ads

What They Are

Full-screen video ads that users choose to watch in exchange for an in-app reward. The user taps a button (e.g., “Watch ad for 50 coins”), watches a 15–30 second video, and receives the reward upon completion.

When to Use Rewarded Ads

• In-game stores — “Watch ad for 50 coins” or “Watch ad to unlock this skin”
• Extra lives / continues — “Watch ad for another chance”
• Daily bonuses — “Watch ad to double your daily reward”
• Content gating — “Watch ad to read this premium article”
• Any time you can offer something valuable in exchange for the user’s attention

When NOT to Use Rewarded Ads

• If your app has no virtual economy or perks — you need something to reward the user with
• If the reward feels meaningless — 1 coin when items cost 1,000 won’t motivate anyone
• As required to use core features — this feels like a paywall disguised as an ad. App stores may reject it. Users will hate it.

Placement Tips

• Make the reward visible and compelling — show exactly what they’ll get before they tap
• Place the button where the user naturally wants more — game over screen, store, bonus section
• Don’t nag — show the option once, clearly. Don’t pop up “Watch an ad?” every 30 seconds
• Reward immediately — the reward should appear the instant the ad completes, not after a loading screen
• Pre-load aggressively — a user who taps “Watch ad” and sees a loading spinner will not tap again

Revenue Expectations

Highest eCPMs of any standard format because the user actively chose to engage. Completion rates are typically 80–95% because the user is motivated by the reward. The limitation is volume — not every user will opt in, and you can’t force them.

Getting the Reward Value Right

The reward needs to feel worth 15–30 seconds of the user’s time:

• Too low: User watches once, realizes it’s not worth it, never taps again
• Too high: You devalue your virtual economy — why buy coins if you can watch ads all day?
• Just right: Meaningful progress (20–30% of a typical purchase), available but not unlimited

A good rule: the reward should equal what the user would earn in 5–10 minutes of normal gameplay.

Native Ads

What They Are

Ads that match the visual design and layout of surrounding content. Instead of a standard banner or full-screen overlay, native ads look like another piece of your app’s content — a feed item, a list entry, a card.

When to Use Native Ads

• Content feeds — news, social, recipe, or video apps where users scroll through items
• List views — search results, category listings, settings screens
• Between content sections — after every 5–10 items in a feed
• Apps where banners feel too “ad-like” and you want higher engagement

When NOT to Use Native Ads

• Games — native ads need a content layout to blend into. Most game UIs don’t have feeds.
• Apps with simple UI — if your app has 2–3 screens, there’s nowhere for a native ad to blend in
• If you can’t invest in design — a poorly implemented native ad that doesn’t match your UI looks worse than a standard banner

Placement Tips

• Match your app’s card/cell design exactly — same fonts, colors, padding, corner radius
• Label clearly — “Sponsored” or “Ad” label is required by policy and builds trust
• Place in natural scroll positions — every 5th–10th item in a feed, not at the very top
• Use the full native ad payload — headline, body, icon, CTA button, media. Don’t show just the headline.

Revenue Expectations

Higher eCPMs than banners because of better engagement. Lower implementation lift but higher design effort. Best ROI in content-heavy apps with strong feed UI.

App Open Ads

What They Are

Full-screen ads shown when a user opens or returns to your app. They appear between the splash/loading screen and your main content, capturing the transition moment.

When to Use App Open Ads

• Apps with frequent open/close cycles — utilities, tools, casual games that users open many times per day
• As supplemental revenue alongside other formats — captures a moment that other formats miss
• Apps with a natural loading moment — if your app already shows a splash screen, the ad fills that time

When NOT to Use App Open Ads

• On the user’s very first launch — they haven’t seen your app yet. Don’t start with an ad.
• On every single foreground — this trains users to dread opening your app
• If your app loads instantly — forcing users to wait for an ad when the app is already ready feels dishonest
• During time-sensitive returns — if the user is coming back to finish a timer, transaction, or game in progress

Placement Tips

• Frequency cap: every 3rd or 4th foreground — enough to monetize without fatiguing
• Skip cold starts — only show on returns (user has already seen the app before)
• Track time away — if the user was gone for less than 30 seconds, they’re probably just switching apps. Skip the ad.
• Pre-load on backgrounding — when the user leaves, load the next app open ad so it’s ready when they return

Revenue Expectations

Good eCPMs (comparable to interstitials) because it’s a full-screen, high-attention moment. Volume depends on how often your users open the app. Utility apps with 5+ daily opens per user see the most benefit.

Rewarded Interstitial Ads

What They Are

A hybrid format: full-screen ads that appear at transition points (like interstitials) but include an opt-in reward. The user doesn’t choose to trigger the ad — it appears naturally — but they earn a bonus for watching it.

When to Use Rewarded Interstitials

• Instead of standard interstitials — same placement, but users feel better about it because they get something
• Between levels in games — “Watch to completion for a coin bonus!”
• After completing actions — the ad appears, and if the user watches fully, they get a reward
• When you want interstitial frequency with rewarded sentiment

When NOT to Use Rewarded Interstitials

• If the reward is unclear — users need to immediately understand what they’re getting
• If you already have rewarded ads in the same flow — two reward-based formats back-to-back confuses the experience
• In apps without a reward economy — same limitation as standard rewarded ads

Placement Tips

• Make the reward visible immediately — show “Watch for 20 coins” on the ad overlay
• Same frequency rules as interstitials — 1 per 2–3 minutes max
• Don’t mix with standard interstitials in the same placement — pick one or the other for each trigger point
• Pre-load alongside your interstitial inventory — use the same trigger points

Revenue Expectations

Higher eCPMs than standard interstitials because of the rewarded component. Newer format, so demand is still growing — may have lower fill in some geos. Best used as an upgrade path from existing interstitial placements.

Format Combinations by App Type

Casual / Hyper-Casual Games

Mid-Core / Strategy Games

Utility / Productivity Apps

News / Content Apps

Social / Community Apps

Decision Framework

When deciding which format to add next, ask:

1. Does my app have natural break points? → Interstitials
2. Can I offer something valuable in exchange? → Rewarded
3. Does my app have a scrollable feed? → Native
4. Do users open my app multiple times per day? → App Open
5. Do I want persistent background revenue? → Banner
6. Do I want interstitial placements to feel less aggressive? → Rewarded Interstitial

Start with the format that maps to your strongest “yes.” Add the second format once the first is performing well. Don’t try to launch all six at once.

Further Reading

• Mobile Ad Monetization Guide — the complete strategy guide
• Ad Monetization Glossary — every term defined
• Android Integration Guide — step-by-step implementation