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Lead GenStandard Ad Banner Sizes
The banner ad sizes that actually perform in B2B display campaigns — dimensions, placements and which ones to build first.
TL;DR
A handful of standard banner sizes drive the vast majority of display inventory and impressions. For B2B, five formats — 300×250, 728×90, 300×600, 320×50 and 970×250 — cover most of the reach, so build those first and skip the long tail of rarely-served sizes.
The banner sizes that actually matter
A small set of standard banner sizes accounts for the overwhelming majority of served display impressions — so building those first gives you nearly all the reach for a fraction of the production effort. The IAB (Interactive Advertising Bureau) defines dozens of formats, but in practice five carry most B2B campaigns.
If you build nothing else, build the 300×250, 728×90, 320×50, 300×600 and 970×250. Together they fit desktop, mobile and high-impact placements across almost all major ad networks.
The core standard sizes
| Size (px) | Name | Where it runs | Best use |
|---|---|---|---|
| 300×250 | Medium Rectangle | Inline, sidebar, mobile | All-round workhorse |
| 728×90 | Leaderboard | Top/bottom of desktop pages | Reach, awareness |
| 300×600 | Half Page | Desktop sidebar | High-impact, more copy |
| 320×50 | Mobile Banner | Mobile screens | Mobile reach |
| 970×250 | Billboard | Above-the-fold desktop | Premium brand impact |
Why 300×250 leads
The Medium Rectangle is the single most valuable format because it works everywhere. It sits inline within article content — where attention is highest — and renders cleanly on both desktop and mobile. When budget or time is tight, this is the size to perfect.
Leaderboard and Half Page
The 728×90 Leaderboard anchors the top of desktop pages and is a reliable awareness format. The 300×600 Half Page gives you real estate for a headline, supporting line and a strong call to action — useful in considered B2B buying journeys where one line rarely closes the case.
Mobile and high-impact
The 320×50 Mobile Banner captures mobile inventory, which is now the majority of impressions on many networks. At the premium end, the 970×250 Billboard delivers brand impact above the fold — powerful, but priced accordingly, so reserve it for launches or account-based plays.
Technical specs to respect
Regardless of size, a few rules keep banners serving cleanly:
- File weight — keep initial load under roughly 150KB; heavier files hurt viewability.
- Format — HTML5 for animation, optimized PNG/JPG for static. Avoid Flash entirely.
- Safe zones — keep logos and CTAs away from edges so nothing gets clipped.
- A clear CTA — one message, one action. B2B display is a reminder, not a full pitch.
Where banners fit in B2B
Display rarely closes B2B deals on its own — average click-through rates hover around 0.35%. Its real value is reach and retargeting: staying visible to buyers who visited your site or match your ICP across a long, multi-stakeholder cycle. Banners keep your brand present so that when the buyer is ready to search — or ask an AI assistant — yours is the name they already recognize.
That means the creative matters less than what it connects to. A sharp banner pointing to a weak landing page wastes the impression. Pair display with strong landing pages, retargeting audiences from your CRM, and organic visibility from SEO and GEO so paid impressions reinforce channels that compound.
How to get started
Build the five core sizes, keep files light, point them at a purpose-built landing page, and wire the clicks back to your CRM so you can measure real pipeline — not just impressions. Want to see how your paid and organic channels work together? Start with a free audit.
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What is the most effective banner ad size?
The 300×250 Medium Rectangle is the workhorse — it fits both desktop and mobile inventory, sits inline with content, and consistently posts the strongest reach and engagement.
How many banner sizes do I really need?
For most B2B campaigns, five sizes — 300×250, 728×90, 320×50, 300×600 and 970×250 — cover the majority of available inventory. Start there before adding niche formats.
What file size and format should banners be?
Keep files under about 150KB and use HTML5 or optimized PNG/JPG. Lighter files load faster, which improves viewability and reduces wasted impressions.
