What Are Microsoft Advertising's Character Limits for Responsive Search Ads?

A Microsoft Advertising responsive search ad allows headlines of up to 30 characters each and descriptions of up to 90 characters each. Advertisers can add up to 15 headlines and 4 descriptions per ad, and Microsoft's system mixes and matches them automatically to serve whichever combination it predicts will perform best, per Microsoft Advertising's official help documentation.

The Full Character Allowances

• Headlines — up to 15 per ad, 30 characters each.
• Descriptions — up to 4 per ad, 90 characters each.
• Path fields — two optional display URL path fields, 15 characters each, appended after the domain to customize the visible destination URL.

Microsoft's system automatically tests different combinations of these headlines and descriptions against each other, learning over time which pairings earn the strongest click-through and conversion performance for a given search query.

These Numbers Mirror Google Ads On Purpose

Microsoft Advertising's responsive search ad format and character limits are built to match Google Ads' RSA format almost exactly — the same 30-character headlines, 90-character descriptions, and 15-headline/4-description structure. That overlap isn't a coincidence; it makes it straightforward to run the same core ad copy on both platforms with minimal rewriting, which matters for advertisers managing both Google Ads and Microsoft Advertising accounts side by side and importing campaigns between the two.

Expanded Text Ads Used Different, Now-Retired Limits

Older guidance floating around the web may reference Expanded Text Ads, which used a 90-character combined title (built from three 30-character headline parts) and a 180-character combined description. Microsoft Advertising stopped supporting new or edited Expanded Text Ads after February 1, 2023 — responsive search ads are now the only text ad format available for new Microsoft Advertising search campaigns, so the 30/90 character limits above are the ones that apply today, not the older Expanded Text Ad figures still referenced in some outdated guides.

Practical Tip for Running Both Platforms

Because the per-headline and per-description limits are identical to Google Ads RSAs, there's rarely a need to write separate copy sets for each platform — the same headline and description assets, built to the 30- and 90-character ceilings, can be uploaded to both without truncation on either side. The main differences between the two platforms tend to show up in audience targeting and auction dynamics, not in the ad copy format itself.

More Headlines and Descriptions Generally Help

While Microsoft Advertising technically accepts as few as three headlines and two descriptions for an RSA to go live, filling closer to the full 15-headline and 4-description allowance gives the system more combinations to test and more signal to learn from. An RSA built with only the minimum number of assets has far less room for Microsoft's optimization to find a strong-performing combination than one built with a fuller, more varied set of headline and description options.

Bottom Line

Write Microsoft Advertising RSA headlines at or under 30 characters and descriptions at or under 90, and the same creative set will run cleanly on both Google Ads and Microsoft Advertising without edits.

Source: Microsoft Advertising Help, "About responsive search ads" (help.ads.microsoft.com, article 60038).