Best Practices for Ad Placement

Placement strategies that maximise viewability and revenue — prioritising viewable positions, using complementary formats, mobile-first sizing, ad density limits, and preventing CLS.

Where and how you place your ad units has a larger impact on revenue than almost any other publisher-controlled factor. This guide distils the most effective placement strategies based on viewability data, demand partner preferences, and user experience research.

Prioritise viewability above all else

The single most impactful thing you can do is ensure your ads are actually seen. Demand partners pay a significant premium for high-viewability inventory. The IAB standard is 50% of the ad in view for 1 second — placements that consistently exceed this attract higher bids over time.

Highest viewability positions (in order):

Sticky footer bar — always in view while the user reads. Near 100% viewability.
Top leaderboard / above the fold — seen immediately on page load.
Mid-article rectangle — visitors actively reading content scroll slowly past it.
Inline with content (between paragraphs or list items).

Low viewability positions to avoid:

Below long articles or comment sections that most visitors never reach
Sidebars on mobile (no sidebar on small screens)
Collapsed sections, accordions, or tabs
Below modal dialogs or cookie banners

Use multiple complementary formats

A typical high-performing page layout combines:

One leaderboard at the top of the content area (728×90 / 970×90 on desktop, 320×50 on mobile)
One or two medium rectangles inline within content (300×250)
One sticky footer bar for ambient monetisation across all scroll depths

Video (outstream) can be added between paragraphs for significant CPM uplift, but keep to one video unit per page.

Respect the space between ads and content

IAB and Google policies require that ads not be placed in a way that mimics content or tricks users into clicking. Practically:

Add at least 30px of whitespace between an ad and adjacent content.
Do not place an ad immediately before or after a navigation element, download button, or CTA in a way that could cause accidental clicks.
Do not label ads as "recommended articles" or similar content-like headings without clearly marking them as sponsored or advertisement.

Mobile-first considerations

More than half of web traffic is on mobile, and mobile CPMs have narrowed significantly with the growth of programmatic. Optimise for mobile:

Use 320×100 instead of 320×50 for the top mobile banner — it is twice the height and typically commands a 30–50% higher CPM.
Add a sticky footer — it is the highest-performing mobile placement and does not interrupt reading.
Keep the above-the-fold area free of ads on mobile. A page where the first thing a visitor sees is an ad (rather than content) has a high bounce rate, which reduces ad engagement and damages your site's long-term SEO and audience quality.

Pre-reserve slot height to prevent CLS

Content layout shift caused by ads loading pushes your content down, degrades user experience, and can damage your Core Web Vitals score. Always add min-height to your slot containers equal to the shortest creative you expect:

/* Leaderboard */
[data-advlume-slot="leaderboard"] { min-height: 90px; }

/* Mid-content rectangle */
[data-advlume-slot="mid-content"] { min-height: 250px; }

/* Mobile top banner */
[data-advlume-slot="mobile-top"] { min-height: 50px; }

Limit density

More ads does not always mean more revenue. Demand partners assess "ad density" — the ratio of ad surface area to content. Pages with more ads than content attract lower bids. As a rule of thumb, keep ads to 30% or less of the visible page area, and never place ads where no content separates them from each other.