Banner ad in 2026: standard sizes and file limits, design rules for a 3-second glance, costs, where to run them, and a step-by-step guide to making one.
A banner ad is a rectangular graphic or animation placed on a website, app, or other digital property to promote a product, service, or brand. Most people have scrolled past thousands of them. That’s both the opportunity and the problem: banner ads are everywhere and cheap to buy, but people have learned to ignore them. This guide covers what banner ads are, the sizes and file limits that matter in 2026, how to design one that earns a glance, what they cost, where to run them, and how to measure whether they’re working.
A quick note: “banner” can also mean the large image at the top of a website, sometimes called a hero banner. This article is about banner advertising, the paid ads placed on other sites.
What Banner Ad Are Good For (and Not Good For)
Banner ads belong to display advertising. Their strengths:
- Awareness. They put your brand in front of many people at a low cost per impression.
- Retargeting. They remind people who already visited your site, which is often their best use.
- Reach. They run across a large network of sites and apps.
- Support for other channels. They keep your message visible alongside search, email, and social.
Their limits are just as real. Click-through rates are low, people develop “banner blindness,” and display clicks rarely convert as well as search clicks, because the viewer wasn’t looking for you. Treat banners as a way to build awareness and bring warm audiences back, not as a replacement for high-intent channels.
Standard Banner Ad Sizes
The Interactive Advertising Bureau (IAB) publishes standard sizes, and Google’s display network accepts a long list of fixed sizes. Sources agree on which ones carry the most inventory:
| Size (pixels) | Name | Where it runs | Notes |
|---|---|---|---|
| 300 × 250 | Medium rectangle | In-content, sidebars, mobile | Widest coverage, the usual first choice |
| 336 × 280 | Large rectangle | In-article placements | A larger alternative to 300 × 250 |
| 728 × 90 | Leaderboard | Top of page on desktop | A desktop standard |
| 300 × 600 | Half page | Sidebar | Big canvas with strong viewability |
| 160 × 600 | Wide skyscraper | Sidebar | Tall and narrow |
| 970 × 250 | Billboard | Top of page | High impact |
| 970 × 90 | Large leaderboard | Top of page | A wider leaderboard |
| 320 × 100 | Large mobile banner | Mobile | More room than 320 × 50 |
| 320 × 50 | Mobile banner | Mobile | Compact mobile standard |
| 468 × 60 | Banner | Legacy placements | Less common today |
Sources suggest starting with 5 to 7 core sizes, typically 300 × 250, 728 × 90, 336 × 280, 300 × 600, 320 × 100, and 320 × 50. Creating a handful of strong sizes beats making ten weak ones.
Responsive Display Ads
Google’s responsive display ads take images, logos, headlines, and descriptions and assemble them automatically to fit almost any slot. Recommended image sizes are a 1.91:1 landscape (1200 × 628) and a 1:1 square (1200 × 1200). They give you reach across more inventory without building every size by hand, but you control the final look less. A common approach is to use responsive ads for coverage and fixed banners in your best-performing sizes so your design appears exactly as intended in premium spots.
File Size and Format Limits
Ads that exceed limits get rejected, and heavy files slow pages down. Reported limits for the Google Display Network:
| Item | Limit |
|---|---|
| Uploaded image ads (JPG, PNG, GIF) | 150 KB per file |
| HTML5 ads | A 600 KB ZIP bundle in one source, with another source citing 150 KB |
| Responsive display ad image assets | Up to 5 MB, with a smaller size recommended |
| IAB guidance | A 150 KB initial load budget for standard units |
Sources conflict on a few of these, especially HTML5 and responsive assets, so check Google’s current specifications before you build. Animation rules also apply: Google’s specs limit how long an animation can run (30 seconds in the guidance I found), so confirm the current limits too.
Design Rules for a Three-Second Glance
Your banner has about as long as a glance. The design needs to do three things quickly: show who you are, say one thing, and tell people what to do.
- One message. Pick one benefit or offer. A banner that tries to say three things says nothing.
- Your brand, visibly. Put your logo where it’s easy to see, since many people won’t click and you still want the impression to count.
- A clear call to action. A button-style element with a specific verb (Shop, Get a quote, Book now) helps.
- Strong contrast and large text. Make sure the text is readable at actual size, including on mobile.
- Very few words. Cut until it hurts.
- A focal point. Use one image or product shot, not a collage.
- A visible border if your background is white or blends into the page, so the ad doesn’t disappear.
- Simple animation, if any. A short change that reveals the offer works better than constant motion, which distracts and may annoy. Avoid flashing.
- Consistency with the landing page. The look, offer, and wording should match where the click goes.
Examples of Banner Messages (Illustrative)
- Retargeting an online store: “Still thinking about it? Your cart is waiting. Free returns.” with a button reading “Finish checkout.”
- Local service: “Same-day plumbing in [your city]. Call now.” with a phone number.
- B2B software: “Cut reporting time in half. See a 5-minute demo.” with a “Watch demo” button.
Where to Run Banner Ads
| Channel | How it works | Good for |
|---|---|---|
| Google Display Network | Your ads appear across a large network of sites and apps | Broad reach and retargeting |
| Microsoft Advertising | Display placements in Microsoft’s network | Adding reach beyond Google |
| Programmatic platforms | Automated buying across many publishers through demand-side platforms | Scale and audience targeting |
| Direct publisher buys | You buy placements on specific sites | Reaching a niche audience in a trusted context |
| Social ad platforms | Image ads in feeds, which differ from classic banners | Reach with social targeting |
What Banner Ads Cost
Display is one of the cheaper ways to buy attention:
- CPM (cost per thousand impressions): One 2026 benchmark puts Google Display Network CPM around $3, and other sources report a wide range depending on quality and targeting.
- CPC (cost per click): Display CPC in recent benchmark roundups runs in the range of about $0.44 to $0.75, with legal and real estate at the higher end in one dataset.
- Conversion rate: Reported display conversion rates are much lower than search, around 0.5% to 1.5% in one source.
Sources disagree on exact figures and many come from vendors, so use them for orientation and measure your own.
Example math: at a $3 CPM and a click-through rate of 0.4%, 100,000 impressions cost $300 and produce about 400 clicks, a cost of about $0.75 per click. If 1% of clicks convert, that’s about 4 conversions for $300, or about $75 each. Whether that’s good depends on what a customer is worth.
Click-Through Rates: Set Expectations Honestly
Reported average click-through rates for banner sizes are typically a fraction of a percent. One 2026 vendor source lists 300 × 250 at about 0.4% to 0.6% and 728 × 90 at about 0.3% to 0.5%. Those are vendor-published and vary by industry and placement, but the broad lesson holds: a CTR below 1% is normal for display. Don’t judge a banner by clicks alone.
Viewability: Was the Ad Even Seen?
An ad can be served and never seen. The industry standard for display viewability, from the Media Rating Council, counts an ad as viewable when at least half its pixels are in view for at least one second. Placement matters, and above-the-fold and in-content units tend to be more viewable than ads at the bottom of a page. Ask platforms and publishers for viewability data, and consider verification tools.
How to Make a Banner Ad, Step by Step
- Set a goal, such as awareness, remarketing, or leads.
- Pick your audience and placements, and whether you’ll use responsive ads, fixed sizes, or both.
- Choose your sizes. Start with the core set above.
- Write one short headline and a clear call to action.
- Design in a banner tool or design software, using your brand colors and fonts.
- Export under the file-size limit in the right format.
- Check the design on mobile and at actual size.
- Build the campaign in your ad platform, with targeting, a budget, and a frequency cap so people don’t see the ad too often.
- Send clicks to a matching landing page with one clear next step.
- Test one variable at a time, such as the headline, image, or button.
Platform Rules and Accessibility
- Follow each platform’s ad policies. Misleading claims, fake system messages, and deceptive close buttons are commonly prohibited.
- Avoid flashing animation, and keep contrast high so more people can read the ad.
- Label offers accurately and include required disclosures.
Measuring Results
| Metric | What it tells you |
|---|---|
| Impressions and viewable impressions | Reach and whether the ad was seen |
| Click-through rate | Whether the creative earned attention |
| Cost per click and cost per acquisition | Efficiency |
| Conversions, including view-through | Business impact, with caution |
| Frequency | Whether people are over-exposed |
| Branded search and direct traffic lift | Awareness effects |
View-through conversions, where someone saw an ad and converted later without clicking, can overstate impact, so compare against a holdout group or a pre-campaign baseline when possible.
Common Mistakes
- Too much text and too many messages
- No clear call to action
- A weak or mismatched landing page
- Using only one size
- Ignoring mobile
- Judging success by CTR alone
- No frequency cap
- Never testing creative
Frequently Asked Questions
- What is a banner ad? A rectangular graphic or animation placed on a website or app to promote a product, service, or brand, bought through display advertising.
- What’s the best banner ad size? The 300 × 250 medium rectangle is the most commonly recommended starting point because it fits the most inventory, followed by 728 × 90, 336 × 280, 300 × 600, and the mobile banners.
- What is the file size limit for banner ads? On the Google Display Network, uploaded image ads are limited to 150 KB, with different limits for HTML5 and responsive ad assets. Check Google’s current specs, since sources differ.
- Do banner ads still work? They work best for awareness and retargeting, and less well as a standalone direct-response channel, since click-through rates are low.
- How much do banner ads cost? Display is typically bought by thousand impressions, with benchmark CPMs around $3 on Google’s network and CPCs often under a dollar, though results vary by targeting and industry.
- What’s a good click-through rate for a banner ad? Reported averages are well under 1%, often around 0.3% to 0.6%, so don’t judge success on clicks alone.
