What Is Ad Refresh and Should Publishers Use It?

Ad refresh reloads an ad unit with a new paid creative after a set time interval or user interaction, generating additional impressions from a single page view. Done right, it increases total session revenue by 20 to 40%. Done wrong, it triggers DSP bid shading, SSP policy violations, and advertiser complaints. This article covers refresh mechanics, policy compliance, CPM impact math, and how to implement viewability-based refresh within your publisher ad monetization strategy.

How Does Ad Refresh Work?

Ad refresh replaces the creative in an active ad slot with a new ad after a trigger condition is met. Each refresh fires a new bid request, runs a new auction, and serves a new impression. The original ad slot generates multiple paid impressions during a single user session.

Three trigger types exist:

Time-Based Refresh

The simplest model. A timer starts when the ad loads. After a set interval (30, 60, or 90 seconds), the ad refreshes with a new creative. The timer resets and the cycle repeats. A user spending 3 minutes on a page with a 30-second refresh sees up to 6 ads in a single slot.

Event-Based Refresh

The ad refreshes when the user takes a specific action: clicking a navigation tab, submitting a form, scrolling past a content section, or interacting with an on-page element. Event-based refresh ties impressions to engagement signals, which preserves ad quality better than blind timers.

Viewability-Based Refresh

The most sophisticated model. The ad only refreshes when three conditions are met simultaneously: the ad slot is in the active viewport (50%+ pixels visible), the minimum time interval has elapsed (30+ seconds), and the browser tab is active (not backgrounded). This combines time-based intervals with real-time viewability verification using the Page Visibility API and Intersection Observer API.

Viewability-based refresh is the only model that consistently passes SSP compliance checks and preserves CPM quality. Blind timers refresh ads that may be off-screen or in background tabs, generating impressions no human sees.

What Are the Policy Rules for Ad Refresh?

Google Ad Manager requires a minimum 30-second interval between refreshes, and you must declare ad refresh in your GAM ad unit settings. Undeclared refresh violates Google's policies and can result in account warnings or suspension.

Google AdSense prohibits publisher-initiated ad refresh entirely. If you're on AdSense, this tactic is not available to you. Mediavine and Raptive handle refresh as part of their managed ad stack with built-in compliance.

SSP policies vary. Magnite and PubMatic accept refreshed inventory but may apply bid modifiers (discounts) on impressions with refresh counts above 2 or 3. Index Exchange accepts refresh with 30-second minimum intervals. Some SSPs reject refreshed inventory outright if not properly declared via the OpenRTB instl or refresh-related fields.

The IAB Tech Lab recommends a 30-second minimum and requires that refresh behavior be declared in bid requests so buyers can make informed bidding decisions. Undeclared refresh is classified as invalid traffic (IVT).

How Does Ad Refresh Affect CPM Rates?

Each subsequent refresh typically earns a lower CPM than the previous one. The first impression in a slot clears at full market CPM. The second clears 15 to 30% lower. The third drops another 10 to 20%. DSPs apply bid shading to refreshed inventory because buyer-side studies show declining attention and engagement with each successive ad in the same slot.

Here's the revenue math:

• Without refresh: 1 impression at $6.00 CPM = $6.00 per 1,000 pageviews from that slot.
• With 30-second refresh (user stays 90 seconds): 3 impressions at $6.00, $4.20, and $3.00 CPM = $13.20 per 1,000 pageviews. Total yield more than doubles despite CPM decay.
• With 30-second refresh (user stays 3 minutes): 6 impressions at $6.00, $4.20, $3.00, $2.40, $2.00, $1.80 CPM = $19.40. Diminishing returns become visible by impression 4, but each additional impression still adds positive revenue.

The break-even question: does the total yield from refreshed impressions exceed the CPM penalty applied to your first impression? Some DSPs shade first-impression bids on ad units they know will refresh, reasoning that the publisher is extracting more value from each slot. In practice, this penalty is small (5 to 10% on first impression) when refresh is properly declared and intervals are 30+ seconds.

Model your specific scenario using the eCPM calculator with your current rates and average session duration.

When Should You Enable Ad Refresh?

Enable refresh on ad units that meet all four criteria:

• High average time on page. Refresh only pays off if users stay long enough to generate multiple impressions. Pages with under 30 seconds average time on page won't benefit. Long-form content, recipe pages, tutorial articles, and tool pages with 2+ minute average session duration are ideal candidates.
• High viewability. Only refresh units that consistently sit in the viewport: sticky sidebars, in-content units users scroll past slowly, and anchor ads. Never refresh below-fold units that users may never see.
• Proper declaration. GAM refresh declaration must be enabled. SSP partners must be informed. Bid requests must carry refresh signals. Undeclared refresh risks IVT classification.
• Not on AdSense. If AdSense is your only demand source, ad refresh violates their policies. Wait until you migrate to a managed network or GAM-based setup.

Avoid refresh on pages with high bounce rates, above-fold units where it causes visible creative swaps that distract readers, and any unit where lazy loading hasn't been properly configured (refreshing an ad that never entered the viewport generates invisible impressions that destroy your viewability score).

Check your refresh revenue contribution against CPM benchmarks by format. If refreshed impression eCPM drops below $1, the incremental revenue may not justify the viewability dilution.