Most ad-budget debates fixate on targeting and bidding. The creative dimensions? Usually an afterthought. That’s backwards. The wrong banner ad sizes will bury a strong campaign before a single auction runs, because half the inventory on the open web won’t even accept your file. We build display creative for agencies and in-house teams every week, and the size set is the first thing we lock. Pick well and your ad lands in the spots people look at. Pick badly and you’re paying for placements nobody sees. Same budget, same targeting. The reach gap comes down to the spec sheet.
So which sizes earn their keep this year? Let’s get specific.
Key Takeaways
- The 300×250 medium rectangle is the single most useful unit. Build it first.
- Google’s top performers are 728×90, 336×280, 300×250, 160×600, and 300×50. Start there.
- Mobile drives most web traffic now, so 320×50 or 320×100 isn’t optional.
- Coverage beats favourites: three to five sizes per campaign fill far more inventory than one.
- Keep image files under 150KB, mind the safe zones, and reach for HTML5 on anything animated.
The Sizes Google Puts First
Google publishes its own list of top-performing ad units, and it’s the cleanest starting point we know of. These five banner ad dimensions pull the most advertiser demand across Google’s network, which means more competition for your slot and, often, better rates.
| Size (px) | Name | Where it earns its place |
|---|---|---|
| 728x90 | Leaderboard | Above main content and on forum sites |
| 336x280 | Large rectangle | Inside article copy or at the end of a piece |
| 300x250 | Medium rectangle | Embedded in text, sidebars, end-of-article |
| 160x600 | Wide skyscraper | Sidebar rail, visible well below the fold |
| 300x50 | Mobile banner | Top or bottom strip on larger phone screens |
Desktop and Mobile Pull in Different Directions
Match the Size to the Job
Different goals reward different shapes. We map the size set to the campaign objective before any design starts:
- Chasing reach and brand recall? Go big and wide. The 728×90 and 970×250 plant your message where it can’t be missed.
- Want clicks from people already reading? The 300×250 and 336×280 slot into content, right at the moment attention peaks.
- Running mobile-first? Lead with 320×50 and 320×100. No desktop unit will rescue a campaign that ignores the phone.
- Retargeting warm visitors? The 300×600 half-page gives you space to make a real pitch, and Google calls it one of its fastest-growing units by impressions.
One pattern holds across all of them. The banner ad formats that read as part of the page beat the ones fighting it. An ad shaped to the layout pulls more attention than a louder unit jammed where it doesn’t belong.
Why One Size Is Never Enough
The most common mistake we fix? Campaigns built around a single size. The creative looks fine. The results stay flat. Coverage is the culprit, not the design.
Every publisher stocks a different mix of slots. Build for one size and you’re fishing in one small pond while the rest of the inventory sits untouched.
Here’s why a family of sizes wins. The same message, rebuilt across 300×250, 336×280, 728×90, 160×600, and 320×100, becomes eligible for slots a single unit could never fill. Same look, five shapes, far more places to appear. Fill rate climbs because the ad server has more options to place when an auction opens up. Three to five units cover most of the open web. Add the half-page and the billboard once the budget reaches for premium placements.
The Specs That Quietly Kill Performance
Sizing is only half the battle. These technical details sink more campaigns than weak creative does:
- File weight. Google caps uploaded image ads at 150KB. That’s a tight ceiling for motion. We hand-build animated banner ads in HTML5, since GIFs blow the limit fast and look rough doing it.
- Static or HTML5? Static JPGs and PNGs render everywhere. HTML5 scales without pixelating and carries motion. For most accounts, we ship both.
- Animation length. Google disapproves animated ads running past 30 seconds, and any loop has to stop at that mark. GIFs also need to sit below 5 frames per second. We keep movement to roughly 3 to 7 seconds, because nobody watches a banner loop for half a minute.
- Responsive display ads. Upload a few assets and Google reshapes them to fit slots you didn’t design for. Useful for coverage, weaker on brand control. Treat them as gap-fillers, not the whole plan.
- Safe zones. Logos and calls to action crowded against the edge get clipped on some placements. Keep the important stuff back from the border.
Right dimensions, wrong file, and the slot still turns you away.
FAQ
How many sizes should a small business build?
Start with three: 300×250, 728×90, and 320×50. That trio shows up across the bulk of standard display inventory. Add 336×280 and 160×600 once you’ve seen which placements convert. Little point paying to design ten units before the data tells you which ones matter.
Are responsive display ads making fixed sizes obsolete?
No. Responsive ads cover odd slots automatically, but they hand creative decisions to an algorithm. Brands that care how their logo crops, how their colours read, and where the call to action lands still build fixed sizes. The two work together rather than replacing each other.
Do social platforms use these same banner ad sizes?
Mostly not. Meta, LinkedIn, and the rest run their own feed-native formats built around square and vertical ratios, not the IAB display set. The dimensions here apply to the open display web and Google’s network. Plan social creative on its own track.
Is the old 468x60 banner still worth building?
Rarely. Google itself notes that advertiser supply for the 468×60 runs thin, which leaves it filling fewer slots and earning less. It was the default banner twenty years ago, back when screens were small. Modern displays swallow it whole. Put that production time into a 728×90 instead and you’ll reach far more inventory for the same effort.
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creative production?
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