IAB ad formats: the complete 2026 guide
Leaderboard, MPU, half-page, sticky, native: dimensions, max weight, CLS best practices and observed click rates.
July 24, 2026
TL;DR
The 5 formats that cover 95 % of needs, with zero CLS and CTRs observed on the Addirectly network.
The formats
- Leaderboard 728×90 — avg CTR 0.3 %, top-of-page.
- MPU 300×250 — CTR 0.6-1.1 %, side column or in-article.
- Half-page 300×600 — CTR 0.8-1.4 %, sticky sidebar.
- Mobile banner 320×50 — CTR 0.4-0.7 %, sticky bottom.
- Native in-feed — CTR 1.5-3 %, best advertiser ROI.
CLS rules
- Reserve height in CSS (
aspect-ratioormin-height). - Load script
asyncwith iframeloading="lazy". - Max 150 KB per creative.
FAQ
Do I need all formats? No — 2 well-placed formats beat 5 poorly integrated ones.
Interstitials? Avoid — penalised by Core Web Vitals.
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