Every guide to "social media image sizes" covers organic posts — the photo you upload to your feed. Paid ad units are a different, often stricter spec entirely: tighter character limits on headlines, different aspect ratio requirements, separate file-size caps, and formats that don't exist anywhere in the organic posting flow (Bumper Ads, Spark Ads, Collection Ads). Media buyers rebuilding creative for each platform from scratch waste real production time re-deriving specs that are all sitting in each platform's own ad-manager documentation. This guide puts them all in one place — image ads, video ads, carousels, and the ad-copy character limits that trip people up more than any pixel dimension.

Image Ad Specs by Platform

Single-image ads remain the highest-volume ad format on almost every platform. Most cluster around a 1.91:1 landscape or 1:1 square canvas, but the exceptions below (Pinterest's tall 2:3, WeChat's compressed 1MB ceiling) will break a one-size-fits-all export.

PlatformAd TypeDimensionsMax File Size
FacebookSingle Image Ad1440×1800 px (4:5)30 MB
InstagramFeed Single Image Ad1440×1800 px (4:5) or 1080×1080 px (square)30 MB
ThreadsSingle Image Ad1440×1440 px recommended30 MB
LinkedInSingle Image Ad1200×628 px (1.91:1)5 MB
X (Twitter)Promoted Post Image1200×1200 px (1:1) or 1200×628 px (1.91:1)5 MB
PinterestPromoted Pin (Static)1000×1500 px (2:3)20 MB (desktop); 32 MB (in-app)
RedditPromoted Post (Image)1080 × 1350 px (4:5, recommended)3 MB (sources vary — see note)
YouTubeDisplay Ad300×250 px150 KB
WhatsAppClick-to-WhatsApp Ad1080×1080 px or 1200×628 px30 MB
NextdoorNewsfeed Ad — Image1200×628 px (1.91:1) or 1200×1200 px (1:1)150 MB
QuoraImage AdFlexible — min width 580 px2 MB
SpotifyDisplay / Overlay Ad640×640 px minimum200 KB
WeChatMoments Ad (Image)800×800 px (1:1)≤ 1 MB recommended
RedNoteIn-Feed Ad1080 × 1440 px (3:4) — same as organic Note20 MB
KakaoTalkBiz Board (Banner Ad)960×300 px300 KB
Where sources disagreeReddit's image-ad file-size cap is genuinely unsettled — current agency guides mostly converge on 3 MB, but a minority still cite 20 MB, and Reddit's own spec page is login-gated with no public archive. Quora doesn't publish an ad file-size figure at all; the 5 MB above is a third-party estimate. Design under the lower number in both cases so you're never the one finding out the hard way.
Image ad specs by platform showing 1.91:1, 1:1, 4:5, and 2:3 aspect ratios, plus notable exceptions for RedNote, YouTube, WeChat, and KakaoTalk

Most paid image ads cluster around landscape, square, or portrait — the exceptions above are the ones that break a one-size-fits-all export.

Video Ad Specs by Platform

Video ad durations vary far more than dimensions — from YouTube's 6-second Bumper Ad to WhatsApp's 241-minute ceiling (in practice, nobody runs a 4-hour ad, but the technical limit is that high because it reuses the organic video pipeline).

PlatformAd TypeResolutionMax DurationMax File Size
InstagramReels Ad1440×2560 pxUp to 15 minutes—
ThreadsSingle Video Ad1440×1800 px recommendedUp to 15 minutes4 GB
LinkedInVideo Ad1920×1080, 1080×1080, 1080×1350, or 1080×1920 px3 sec – 30 min75 KB – 500 MB
X (Twitter)Video Ad1920×1080, 1200×1200/1080×1080, or 1080×1920 px15 sec recommended; 2 min 20 sec max1 GB
PinterestPromoted Pin (Video)1080×1920 px or 1080×1080 px4 sec – 15 min2 GB
TikTokIn-Feed Ad1080×1920 px recommendedUp to 10 min (unlimited for Spark Ads)500 MB
TikTokTopView Ad1080×1920 px5–60 seconds—
SnapchatSingle Video Ad1080×1920 px3 sec – 3 min1 GB
RedditPromoted Post (Video)1440×1080 px or 1920×1080 px2 sec – 15 min1 GB
YouTubeSkippable In-Stream1920×1080 pxAny length; skippable after 5 sec—
YouTubeNon-Skippable In-Stream1920 × 1080 pxUp to 15 sec (30 sec for CTV)—
YouTubeBumper Ad1920 × 1080 pxMaximum 6 seconds—
WhatsAppClick-to-WhatsApp Ad1080×1080 px or 1920×1080 pxUp to 241 minutes4 GB
NextdoorNewsfeed Ad — Video1920×1080 px or 1080×1080 px2–300 sec (under 30 recommended)500 MB
SpotifyVideo Ad (Sponsored Session)1280×720 px or 720×1280 px15–30 seconds500 MB
WeChatMoments Ad (Video)1280×720/1280×960 (horizontal) or 720×1280 (vertical)6–15 sec (up to 30 sec for some formats)100 MB (horizontal)
TikTok's Spark Ads exceptionTikTok's standard In-Feed Ads cap out at 10 minutes and 500MB, but Spark Ads — which boost an existing organic post rather than uploading new creative — inherit that post's full organic limits instead. If you're promoting a video longer than 10 minutes, Spark Ads are the only path, not a bug in the standard ad flow.
Video ad specs by platform comparing 9:16 vertical and 16:9 horizontal formats, with duration limits for TikTok, YouTube, LinkedIn, Spotify, WeChat, and WhatsApp/Messenger

Vertical dominates mobile placements; duration limits vary far more between platforms than the dimensions do.

PlatformDimensions per CardMax File Size
Facebook1080×1080 px—
Instagram1080×1350 px (4:5) or 1080×1080 px—
Threads1440×1440 px—
LinkedIn1080×1080 px—
X (Twitter)800×800 px—
Pinterest1000×1500 px—
Reddit1200×1500 px (4:5) or 1200×1200 px20 MB (static); 3 MB (GIF)
Nextdoor1200×1200 px minimum150 MB
KakaoTalk800×600 or 800×400 px—
Carousel ad specs showing a 10-card carousel example alongside ad copy character limits for Snapchat, Facebook, LinkedIn, X, Reddit, Pinterest, and Nextdoor

Carousels typically run 2–10 cards per ad. Write the headline first — paid copy limits are consistently tighter than the equivalent organic field.

Ad Copy Character Limits by Platform

This is the table that catches people. Ad headlines and body text almost always have a tighter cap than the equivalent organic post field on the same platform — Facebook's organic post allows 63,206 characters, but its ad headline maxes out at 40.

PlatformFieldLimit
FacebookAd Headline27 characters
FacebookAd Primary Text50–150 characters
FacebookAd Description30 characters
InstagramAd Primary Text125 characters
InstagramAd Headline40 characters
ThreadsAd Primary Text500 characters
LinkedInAd Headline70 characters
LinkedInAd Intro Text150 characters
LinkedInAd Description100 characters
X (Twitter)Ad Headline70 characters
X (Twitter)Ad Body Copy280 characters
PinterestAd Title100 characters
PinterestAd Description800 characters
SnapchatAd Headline34 characters
SnapchatAd Brand Name25 characters
RedditAd Headline300 characters
RedditAd Body500 characters
WhatsAppBusiness Message Template1,024 characters
NextdoorSponsored Post Headline70 characters
NextdoorSponsored Post Body1,700 characters
QuoraText Ad Headline65 characters
QuoraText Ad Body105 characters
WeChatAd Headline30 characters

Platforms Where Ads Don't Follow a Fixed Spec

Not every platform treats ads as a distinct creative product. Two worth knowing about specifically:

Design once, export manyMost image ad specs across Meta platforms (Facebook, Instagram, Threads) and WhatsApp already converge on 1080×1080 or 1200×628 — build your master creative at 1200×1200 and you can crop down to nearly every one of them without re-designing from scratch. Video is less forgiving: budget for at least a 9:16 and a 16:9 export of anything going to more than two platforms.