Key Takeaways
- Google RSA: 15 headlines at 30 chars each, 4 descriptions at 90 chars. Fill every slot. Really.
- Meta’s mobile feed chops primary text at 125 chars. Get the hook into the first 40 or forget about it.
- LinkedIn’s headline cap is 70 characters, with no “see more.” Go two over and those two are gone forever.
- TikTok in-feed captions max out at 100, but in practice anything past 50 gets clipped on smaller phones.
- X still counts in 280. Square images beat 16:9 on mobile, which is where most of the traffic lives.
- Vertical > square > horizontal on every mobile placement. If you only make one version, make it 9:16.
- Don’t trust last quarter’s cheat sheet. Specs drift. Check the platform’s own help center before you launch.
Quick reference
| Network | Headline | Primary / Caption | Notes |
|---|---|---|---|
| Google RSA | 30 x 15 | 90 x 4 (desc) | Min 3 headlines / 2 descriptions |
| Meta Feed | 40 | 125 (then “See more”) | Desc 27; Reels Overlay 20 |
| LinkedIn SI | 70 (hard cap) | 150 shown / 600 max | No “see more” on headline |
| TikTok In-Feed | n/a | 100 (caption) | Real ceiling ~50 visible |
| Microsoft RSA | 30 x 15 | 90 x 4 (desc) | LinkedIn audience overlay |
| X (Twitter) | n/a | 280 | 1:1 beats 16:9 on mobile |
| Pinterest Pin | 100 (title) | 500 (desc) | 2:3 required |
| 300 (title, API) | n/a | Under 50 outperforms dramatically | |
| Snapchat | 34 | n/a | Brand 25 chars |
| Amazon SB | 50 | n/a | Listing-driven |
Screenshot this. Come back to it. Then read on for the detail behind each row.
You know this song
You wrote the headline for Google. Solid, 28 characters, brand name tucked in nicely. Now you’re copying it into Meta, which wants a primary text AND a headline AND a description, and you’re not sure which one is the “real” place for the value prop. So you try to trim. You give up and paste the whole thing into primary text. Then TikTok demands vertical video, and you don’t have vertical video, and Pinterest wants 2:3, not 1:1, and you’re back in Figma re-cropping the asset you already cropped last week.
Every network has its own rules. The rules change. They’re documented in twelve different places, and at any given moment half of them are out of date. Miss one and your campaign gets flagged, or the creative renders sideways, or the ad just doesn’t ship and you don’t find out until Monday.
We put this together because we needed it ourselves. Specs verified against each platform’s current help docs as of April 2026.
The Responsive Search Ad rules have been stable for a while: 15 headlines at 30 characters, 4 descriptions at 90, two display paths at 15 each. Minimums are 3 headlines and 2 descriptions. Google rotates combinations and learns what works, so give it real variety. Five headlines that say the same thing in slightly different adjectives is not variety.
Display wants 1200x628 landscape, 1200x1200 square, plus a logo at either 1200x300 landscape or 1200x1200 square. Long headlines cap at 90, short ones at 30, descriptions at 90. Google’s auto-resize exists. It is not good. Upload native sizes when you can.
YouTube in-stream: non-skippable runs up to 15 seconds globally. Skippable goes up to 3 minutes, and nobody watches the back half, so don’t fool yourself. 16:9, 1:1, or 9:16 depending on placement. If mobile is where your audience lives, 9:16 almost always wins.
Performance Max will auto-generate video from your images and text if you don’t supply any. It’s bad. Delivery gets throttled, the creative looks like a PowerPoint with sound effects, and you’ll sit there refreshing the dashboard wondering why nothing is spending. Supply real video if you want PMax to work.
Meta
Feed ads take 1:1 or 4:5, images at 1080x1080 minimum. Primary text shows cleanly up to 125 characters on mobile, then “See more” takes over. Headline is 40. The description for the Feed link preview is a stingy 27 characters. 4:5 owns more mobile real estate than 1:1, and mobile is where 95% of Meta impressions happen, so 4:5 it is.
Stories and Reels: 9:16 vertical, 1080x1920. Stories run 15 seconds; standard Reels ads cap at 60. (There’s a 90-second extended format, but it needs special access and isn’t the default. If you’re not sure, you have 60.) Completion rates collapse well before the ceiling. Lead with the hook in the first three seconds. Not the logo. The hook. The logo can come after people have decided they care.
One mean little Meta field worth flagging: Reels Overlay text is 20 characters. That’s not a value prop, it’s a glance. Plan accordingly.
Carousel ads: up to 10 cards, 1:1, 1080x1080 per card, primary text 125, headline 40, description 20. Useful for showing a bunch of products. Not useful for anything that needs a story.
LinkedIn is fussy. It’s also where most of the B2B buyers actually show up in volume. Live with it.
Single image ads show the first 150 characters of intro text before “see more,” with a 600-character hard ceiling. Put the actual message in the first 150. Anything past that is bonus material most people won’t see.
Headline is 70 characters, hard cap, no expansion. Write over 70 and the tail is invisible forever. Description caps at 100. Images at 1200x627 horizontal or 1200x1200 square.
One piece of free advice while we’re here: no stock photos of smiling businesspeople in conference rooms. LinkedIn users have developed an almost allergic reaction. CTRs show it.
Video ads run 5 seconds to 30 minutes on paper. The practical ceiling is more like 30 seconds, because that’s where most people bail. 4:5 and 1:1 outperform 16:9 on mobile, and a surprising amount of LinkedIn is mobile now, even for B2B.
Message ads get a 1500-character body and a 20-character CTA button. Use them sparingly. LinkedIn penalizes senders whose messages get flagged or ignored, and once you’re in the penalty box, getting out is slow.
Document ads accept a PDF up to 10 pages. Great for whitepapers. Bad for anything that needs urgency.
TikTok
Feed ads are 9:16, 1080x1920 minimum. Run length between 5 and 60 seconds, sweet spot 15 to 30. Caption takes 100 characters including hashtags, but anything past 50 tends to get clipped on smaller phones. So the rule is simple: lead with the point in the first 50. Trailing hashtags can live past the cutoff. Nothing you need people to see should.
Spark Ads (boosted organic content) inherit the 2,200-character caption from the original post, but the visible portion in the feed is still the first chunk. Spark Ads tend to beat traditional in-feed ads by a lot, for one reason: they look like regular content because they are regular content.
Which brings us to the only rule that matters on TikTok: if the ad looks like an ad, engagement falls off a cliff. Shoot vertical. Use trending audio. Don’t use stock. The platform’s native style is specific, and not matching it is the fastest way to burn money here.
TopView (the placement that autoplays when users open the app) runs up to 60 seconds in 9:16. It’s expensive. It works for launches. Probably not where you start.
Microsoft Ads
Microsoft Responsive Search Ads match Google at 15 headlines x 30 characters and 4 descriptions x 90 characters. Microsoft Audience Network (their display network) takes 1200x628 images, 50-character headlines, 90-character descriptions.
The reason to actually pay attention to Microsoft isn’t search, though. It’s the LinkedIn-audience overlay. You can layer LinkedIn company size, industry, and job function directly onto search campaigns. Nobody else offers that, and for B2B, it’s a genuine edge most teams ignore because they never got around to running Bing.
Amazon
Sponsored Products pulls the title from your listing with no override. Sponsored Brands gets a custom 50-character headline, 400x400 logo, 1200x628 hero image. Sponsored Display generates from the product page but lets you add a 50-character custom headline plus logo.
Amazon DSP (self-serve display) plays by the usual IAB dimensions: 300x250, 728x90, 160x600, 300x600, and so on. Treat Amazon like a retail search engine, not a feed, and the creative decisions get a lot easier.
Standard Pin ads want 2:3, ideally 1000x1500. Title 100 characters, description 500. Vertical is the whole point. Square pins get visually clipped and underperform.
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Get started →Video Pins: 9:16 or 1:1, 4 to 15 seconds, autoplay on mute. Lead with visuals. Captions matter more than audio here because most of the session is silent.
Idea Pin ads go up to 20 frames, all 9:16. Good for tutorials and step-by-steps.
Snapchat
Single Image or Video Ad: 9:16, 1080x1920. Videos can run up to 180 seconds; keep them under 15 anyway. Snapchat’s 5-second swipe window is brutal. The hook lands in 3 seconds or the user is already gone. Brand name is 25 characters, headline 34.
Story Ads are collections of 3 to 20 tiles, same 9:16 specs. Collection Ads pair a hero asset with a strip of product tiles below.
X (Twitter)
Promoted Tweets run on the usual 280-character tweet limit. Images at 1200x675 (16:9) or 1200x1200 (1:1). Up to 4 images per post. On X, 1:1 consistently outperforms 16:9 on mobile, and almost all of X’s traffic is mobile. Go square.
Video Ads: practical cap is 15 seconds for most placements, 2:20 for Pre-Roll. Captions are mandatory. So is a thumbnail frame that reads coherently when the video is paused, which is most of the time.
Promoted Posts (image): the API accepts up to 300 characters on the title, but Reddit’s own performance data is clear that headlines under 50 characters drive dramatically lower CPA. Write short. Image at 1200x628 or 1080x1080. Promoted video: 16:9, 1:1, or 9:16, up to 15 minutes. Watch time falls off hard past 30 seconds, same as everywhere else.
Reddit’s audience is openly hostile to anything that looks corporate. Copy that reads like a Redditor wrote it will outperform polished ad copy by a wide margin. The marketing instinct on Reddit is almost always wrong. Strip the varnish. Say the thing.
Spotify
Audio Ads: 15 or 30 seconds, 640x640 companion image, optional CTA overlay. Get the brand name in the first 5 seconds; half the audience is half-listening.
Video Ads: 15 to 30 seconds, 16:9 on desktop, 9:16 on mobile. These only play when the user is actively looking at the app (skipping a track, adjusting volume), which is a mercifully attentive moment and one of the few places where a video ad isn’t competing with three other things at once.
Apple Search Ads
Your ad is your App Store creative. There’s no ad-level image upload. Custom Product Pages let you rotate variants by search term. Search Tab ads require a Product Page with a video component, or a custom creative set built in App Store Connect.
If you want creative optimization on Apple Search Ads, you’re optimizing your App Store listing. That’s the job. It’s a different muscle than ad copy and worth treating as a separate workstream.
One honest note
Specs move. Meta tweaks something quarterly. TikTok rolls out new formats without much warning. LinkedIn tightened its headline cap a couple years back and plenty of specs pages still haven’t noticed. Last quarter’s internal cheat sheet is a liability, not an asset, and the team member who “keeps the doc updated” is almost always behind the platform docs by weeks.
If you’re running on three or more networks, creative reformatting is probably the biggest hidden time sink in your week. Nobody talks about it at conferences. Automate it if you can. Figma templates with each platform’s specs pre-built will hold up through two or three networks. Past that, the math tips toward tooling.
AdPlus validates creative against every network’s current specs at upload, so a stale asset fails loudly instead of running with a weird crop nobody catches until someone sends you a screenshot on Thursday. Free during public beta.
Email corrections to [email protected]. We sweep this post monthly and roll in real fixes.
FAQ
How often do ad network specs actually change?
More often than anyone admits. Meta and TikTok push meaningful changes a few times a year. Google and LinkedIn are more stable but still adjust character counts, aspect ratios, and asset requirements every quarter or so. Safe habit: re-verify against the platform’s own help center before every new campaign, especially if it’s been more than three months since your last one on that platform.
What’s the single most common creative mistake across networks?
Using the same aspect ratio everywhere. Usually 16:9. It works on YouTube and desktop Meta and is actively hostile on mobile placements, which is where the traffic lives. If you’re only producing one version of your creative, make it vertical or square. You can letterbox 9:16 down to 16:9. You can’t un-crop the other direction.
Is there a tool that handles all these specs automatically?
A few exist at various price points. Running on two networks or fewer, a Figma template per platform works fine and costs you nothing. At three, you start to feel the pain. At five, the math tips toward a tool.
What actually happens if I go over a character limit?
Depends on the network. Google won’t let you save the ad. Meta accepts it and truncates with “See more” on mobile around 125 characters of primary text. LinkedIn is the least forgiving: past the 70-character headline, the tail is invisible with no way to expand. Treat the limit as a hard cap and write two characters short if you can.
Do emoji count as one character or more?
Depends. TikTok, X, and Google count most emoji as one. LinkedIn counts them as two (UTF-16 surrogate pairs), which eats your 70-character headline budget fast. Google also counts each character in Chinese, Japanese, and Korean as two. If emoji matter to the copy, test it in the platform’s own ad preview before you trust the counter on whatever tool you’re drafting in.
Which field should I write first when adapting one ad for multiple networks?
LinkedIn headline. Seventy characters, hard cap, no expansion, the tightest real constraint in the mix. If the core promise fits there, it fits everywhere else. Meta primary text (40-character mobile hook) goes second. Everything longer expands from that base. Working tight-to-loose saves a full rewrite pass.
Do video length limits actually matter if my ads are short?
Not much. The completion-rate curves matter a lot more. Meta Reels allows 60 seconds standard; completion collapses past 15. TikTok allows 60; sweet spot is 15 to 30. LinkedIn technically allows 30 minutes; views fall off a cliff past 30 seconds. Treat the max as a fence, not a target. Write for the first three seconds and assume you’ve got 15.
How do I stay on top of spec changes without doing it manually?
Three options. Subscribe to each platform’s advertiser newsletter (they all have one; quality is uneven). Put a quarterly reminder on your calendar to re-verify the networks you actually spend on. Or run creative through a multi-network ad tool that validates against current specs at upload, so a stale asset fails loudly instead of running with a weird crop nobody catches until a screenshot shows up in Slack on Thursday.
Last verified: April 23, 2026. Cross-checked against each platform’s current advertiser help docs. We review and update this post monthly; email corrections to [email protected].