Banner Ad Sizes That Actually Perform (and Which to Skip)

Banner sizes look like a trivia question and behave like a strategy decision. The dimensions you choose determine which inventory you can even bid on, how much of the page you occupy, and — for publishers — whether a slot earns its keep or quietly costs you readers. This guide walks through the six sizes that matter, what each is genuinely good for, and how to choose from either side of the marketplace.

The six sizes worth knowing

Adgora serves six display formats, and they are not arbitrary — each maps to a real place on a real page.

300×250 — Medium Rectangle

The workhorse. It fits a desktop sidebar, drops cleanly into mobile in-content, and has the deepest demand of any size because everyone builds for it. Its shape is genuinely useful: nearly square, so an image and a few words both read at a glance. If you make one banner, make this one.

728×90 — Leaderboard

The classic top-of-page strip. Wide, shallow, and desktop-only in practice. Good reach, unremarkable engagement — it sits exactly where the eye has been trained for twenty years to skip. Reliable filler rather than a star.

300×600 — Half Page

A tall sidebar unit and one of the highest-earning display sizes. The height is the point: it stays in view as the reader scrolls, so it accumulates real attention instead of a glance. Strong bids follow. Needs a genuine sidebar to live in.

160×600 — Wide Skyscraper

The narrow tall one. Same scroll-persistence idea as the half page, less room to say anything. It survives on narrow-sidebar layouts where 300×600 will not fit. Fine, not exciting.

320×50 — Mobile Banner

The mobile strip, usually anchored. Tiny, but it is on the device where most traffic actually is, so volume is enormous. There is room for roughly five words and a logo — treat it as a reminder, not a pitch.

970×250 — Billboard

The big desktop statement unit. Huge canvas, high impact, high bids — and it eats the top of the page. Brilliant for brand, punishing if it shoves your content below the fold.

If you are buying: which to build

Do not make all six on day one. Build the trio that covers most inventory:

• 300×250 — the broadest reach, works desktop and mobile.
• 728×90 — desktop top-of-page coverage.
• 320×50 — mobile, where the volume lives.

Validate the campaign with those, then add 300×600 and 970×250 for the placements that proved they pay. Building eight sizes for an untested offer is work you may bin.

Design rules that survive contact with reality: one message, legible at actual size (zoom out to check — most banners are designed at 200% and shipped at 100%), a visible action, and a fast-loading file. And be honest about what display is for. Banner blindness is real; for direct response, native or push will usually beat a banner on the same budget. Display earns its place as cheap, scalable presence alongside a stronger format — see ad formats explained for the full comparison.

If you are publishing: which to place

Every slot is a trade between revenue and reader patience. A rough hierarchy of what tends to earn:

• Highest eCPM: 300×600 and 970×250 — big, in-view, hard to ignore.
• Best all-round: 300×250 — deep demand means it almost always fills.
• Volume: 320×50 — small money per impression, but on the majority of your traffic.
• Filler: 728×90 and 160×600 — dependable, rarely the star.

Two rules keep this from backfiring. First, fill beats size — a 970×250 that goes unsold is worth exactly nothing, while a 300×250 that always fills compounds quietly. Second, judge revenue per session, not per impression: a billboard that pushes your article below the fold can lift eCPM while shrinking the traffic that produced it. Set a floor eCPM per zone so a prime slot never clears cheap, and read the whole picture in the eCPM playbook.

Mobile is the default, not the afterthought

Most traffic on most sites is mobile, which quietly demotes half the desktop sizes. A layout built around 728×90 and 160×600 is optimizing for the minority of your readers. In practice the mobile-first stack is 300×250 in-content plus 320×50 anchored — and if your traffic skews to tier 2 and 3 geos, it skews even harder to mobile and to slower connections, where a heavy creative fails before your offer gets a chance.

How pricing works across sizes

Bigger units earn more because they earn more attention, and that flows through the auction rather than a rate card. Every bid — CPM, CPC, or CPA — is normalized to an effective CPM and ranked first-price, so a well-targeted 300×250 with a strong click-through rate can out-earn a lazy 970×250 bid for the same reader. Size gives you a ceiling; relevance decides whether you reach it. The mechanics are in CPC vs CPM vs CPA, and how to sharpen relevance is in the ad targeting guide.

Create an Adgora account to run display or place your first zone, or see the sizes and starting bids on the ad formats page.

Key takeaways

• 300×250 is the one to build first — deepest demand, works desktop and mobile.
• Buyers: start with 300×250, 728×90, 320×50; add 300×600 and 970×250 once a placement proves out.
• Publishers: 300×600 and 970×250 earn most, but fill beats size and revenue per session beats eCPM per impression.
• Mobile is the default — 300×250 in-content plus 320×50 anchored covers most real traffic.
• Display is weak for direct response alone — pair it with native or push rather than relying on banners.