Crypto banner ads: sizes, formats and what gets rejected

Seven image sizes are accepted on PraxAds, and six of them are standard IAB display units. That's the complete creative surface area for crypto banner ads on our network, and it's smaller than you'd get elsewhere on purpose. We take images only, in PNG, JPG, GIF or WebP, and we don't accept HTML or JavaScript creatives at all. A banner that can't execute code can't fingerprint devices, redirect users, or carry a payload, and in crypto advertising that class of abuse is exactly what publishers and readers have learned to expect.

Here's what to build, at what size, and what will get a creative sent back.

The sizes and where they run

The campaign form lists the accepted dimensions when you upload. Six map directly to the fixed-size units in the IAB Standard Ad Unit Portfolio (July 2017, version 1.1):

• 300x250, medium rectangle, in-content and sidebar slots and mobile
• 728x90, leaderboard, top of page on desktop
• 300x600, half page, desktop sidebar
• 970x250, billboard, top of page on wide desktop
• 320x50, smartphone banner, anchored to the bottom of a mobile screen
• 160x600, skyscraper, desktop sidebar

The seventh accepted size, 1200x630, sits outside the IAB fixed-size set and serves image-led placements such as sponsored-content headers.

If you make only two, make the 300x250 and the 320x50. The medium rectangle runs in the widest range of contexts, and the smartphone banner covers mobile, where a large share of crypto traffic lives. If you make four, add the 728x90 and the 300x600.

File weight, resolution, and the mobile reality

The IAB portfolio publishes file weight guidance per unit, and it's worth respecting even where a network doesn't hard-enforce it: 150 kB initial load for a 300x250, a 728x90 or a 160x600, 200 kB for a 300x600, 250 kB for a 970x250, and just 50 kB for a 320x50. A heavy banner loads late, and a banner that loads after the reader scrolls past the slot is an impression you paid for and nobody saw.

Export at 2x resolution for sharp rendering on high-density screens, then compress. WebP typically lands well under the weight guidance at 2x. Test the result at actual size on a phone, since a 320x50 viewed on a designer's monitor at 400 percent zoom tells you nothing about legibility in the wild.

Design-wise, the constraints of a small static image are your friend. One line of text a reader can process in under a second, one visual element, one button-shaped call to action, your name or logo. If the value proposition needs a paragraph, the paragraph belongs on the landing page.

Why image-only is a feature

HTML5 creatives can animate, expand, and adapt. They can also spawn pop-ups, chain redirects, mine data, and deliver malware, and rich media has been a recurring vehicle for all of these across the ad industry. We removed the category of risk instead of trying to police it. Static and simple animated images can't execute anything.

For you as an advertiser, the practical consequences are mostly positive. Production is cheaper and faster. Files are reviewable at a glance, which keeps our moderation inside the published 48 hours from sign-off to live. And publishers accept the placements more readily, because nothing in the creative can damage their page or their readers.

Animated GIFs are allowed within the format list. Keep loops short and avoid strobing effects, and remember the file weight guidance applies with more force to animation than to stills.

What gets crypto banner ads rejected

Every creative on PraxAds is reviewed by a person before it serves, and every rejection comes back with a written reason. These are the reasons we write most.

• Guaranteed or implied guaranteed returns, "100x", "risk-free", fixed profit percentages
• Fake interface elements, counterfeit system dialogs, imitation play buttons, or fake close buttons designed to harvest misclicks
• Mismatch between the creative's claim and the landing page it links to
• Impersonation of exchanges, wallets, tokens, or public figures
• Unreadable text, stretched or blurry images, or missing advertiser identity

Two patterns are worth spelling out. The mismatch rule means we review the banner and the destination together, so a compliant image linked to a page promising guaranteed yield fails as a unit. And the fake-UI rule exists because tricked clicks poison everyone: the reader who got deceived, the publisher whose page did the deceiving, and you, since a click obtained by trickery converts at approximately zero and you paid for it.

A rejection isn't a ban. Fix the stated issue, resubmit, and your prepaid balance is untouched throughout, since campaigns only draw down when impressions actually serve.

Build for the click after the click

You can check whether your banners work because every placement carries UTM tags that land in your own GA4. That changes how you should design. A curiosity-gap banner ("You won't believe this chart") can win clicks and still lose money, because the sessions it produces bounce immediately. A plain banner that states the product filters out everyone who was never going to convert, before you pay for the click on a CPC campaign or burn the impression's attention on a CPM one.

Our auction sharpens this further. Allocation weights each bid by smoothed click-through rate, so a creative that earns clicks honestly wins more of the available impressions at the same bid price. The system pays you in delivery for making banners people genuinely want to click.

If your banner needs trickery to get clicked, the problem is the offer, and no file format will fix it.

Run two creatives per size from day one, let the click-through data pick the winner, and retire the loser without sentiment. The IAB's guidance puts a 320x50 smartphone banner at 50 kB on initial load, a third of what a 300x250 is allowed.