Where to put ads (without wrecking your page)

Advertisers don’t pay for ads that load; they pay for ads that are seen. The industry measure is viewability — the MRC standard is at least 50% of the ad’s pixels on screen for one continuous second (30% of the area for large formats over 242,500 pixels). In 2026 the cross-network display average sits around 72% (digitalapplied 2026 benchmarks); 70% is the widely-accepted floor, strong publishers aim for 75%+, and anything under 60% is a signal to fix your layout. Where you place an ad is the biggest thing you control about whether it clears that bar.

Viewability by placement

Not all positions are equal, and the differences are large. These are typical viewability ranges by placement (PubPower 2026, Publift):

Placement	Typical viewability	Why
Mobile anchor / sticky footer	85–95%	Stays pinned in the viewport — the highest-viewability unit on mobile
Sticky vertical sidebar	80–90%	Persists as the reader scrolls; 2–3× the visibility time of a static unit
Leaderboard below the nav	75–85%	Best in-flow spot; ~19% higher than the same unit above the nav
In-content rectangle (after ¶2–3)	70–80%	Sits where engaged readers actually are
Header banner above the fold	55–70%	Overrated — it loads before the reader settles, and they scroll past

The myth worth killing: above the fold ≠ automatically viewable. A header banner that paints before the reader has focused, then scrolls out of view, underperforms an in-content unit they actually reach. Position for dwell, not just for “high on the page.”

The trade on the sticky units: a mobile anchor footer is near-ceiling on viewability but suffers banner blindness — high views, weaker clicks — so it earns its slot only if it doesn’t crowd the read.

Sizes: which units actually convert

Larger and taller wins, but “best” depends on whether you’re optimizing clicks or fill. By click-through rate, 2026 benchmarks rank the standard units like this (digitalapplied):

Size	Format	CTR
336×280	Large rectangle	0.71%
300×600	Half-page	0.61%
970×250	Billboard	0.54%
728×90	Leaderboard	0.42%
300×250	Medium rectangle	0.31%
320×50	Mobile banner	0.28%
160×600	Wide skyscraper	0.25%

Two things to read from that table. The 336×280 large rectangle is the CTR leader and worth preferring over a plain 300×250 in-content. And the 300×250, despite a middling CTR, is the volume workhorse — roughly 35% of all display impressions — so it’s your reliable baseline, not your ceiling. Advertisers specifically bid up the premium “high-impact” formats — 970×250, 300×600, and 336×280 — at higher CPMs. And vertical formats (300×600, 160×600) average about 22% higher viewability than 300×250 and 728×90 (Publift), because a tall unit stays in view through more of the scroll. If your layout only ships small horizontal units, you’re leaving money on the table.

Speed is a placement decision

This is the part most “ad placement” advice misses: viewability is downstream of performance. An ad that renders quickly is on screen before the reader scrolls past it; an ad gated behind a slow, janky load often misses its one-second window entirely. Google’s own analysis ties better Core Web Vitals to higher ad revenue (web.dev) — fast pages literally make your ads worth more.

Two non-negotiables:

1. Reserve every slot’s space in CSS (fixed dimensions or min-height) so ads don’t shove content down when they load. Unreserved slots are the #1 cause of bad CLS.
2. Load ad scripts asynchronously so they don’t block render and tank LCP / INP.

The reserve is a judgment call — too little and you still shift, too much and you get an empty gap on unfilled impressions. A working starting table:

Unit	Typical render	Reserve (min-height)
Mobile anchor / 320×50	50–100px	100px
In-content rectangle (300×250)	250–280px	280px
Large rectangle (336×280)	280px	300px
Half-page sidebar (300×600)	600px	600px

This is exactly why a lean, fast stack pays off twice — once in hosting cost, once in ad revenue (see you don’t need WordPress). And it’s the same reason the reserved-space unit shows up in every one of our platform setups, from Astro to Next.js.

How many is too many?

More slots isn’t more money past a point. AdSense removed its old hard cap — it once limited you to three ad units, three link units, and two search boxes per page — and now governs density through its Valuable Inventory policy: ads must not exceed your content, and Google may limit or disable serving on pages with little value or excessive advertising.

So the ceiling is judgment, not a number. Practical guidance that stays clear of banner blindness and policy risk:

• Long-form desktop article: ~4–5 units total, spaced through the content.
• Mobile: ~1 above the fold + 1–2 in-content.

Excessive density triggers banner blindness, drags down page experience, depresses per-unit viewability, and risks both rankings and network standing. Place fewer, better units in the spots that are actually seen — then make the page fast enough that they stay seen. Once your placement is dialed in, the number that tells you whether it’s working is your page RPM.