Reddit Ad Specs: Sizes, Limits and Formats for Every Reddit Ad Type

Reddit ad specs come down to a few numbers. Headlines can run 300 characters, but Reddit recommends 100 or fewer and 80 if you want to be safe. Destination URLs can be 268 characters. Media works best in 1:1, 4:5, 4:3 or 16:9. Image ads take JPG, PNG or GIF files up to 3 MB. Video ads take MP4 or MOV files up to 1 GB and 2 seconds to 15 minutes long. Carousels hold 2 to 6 images, and free-form ads hold up to 20 images, 5 videos and 40,000 characters of text.

This guide puts every Reddit ad type's specs in one place, as of October 2026, taken from Reddit's own help center. It also shows where Reddit's pages disagree with each other, and gives you one creative kit that covers every format. It's written for marketing teams at brands that sell products people research before they buy.

Key takeaways

• Reddit's four core self-serve ad types are image, video, carousel and free-form. Reminder, interactive (beta), AMA and product ads build on them, and takeovers are sold only through Reddit's sales team. Conversation ads are a placement, not a separate creative.
• The safest single image is landscape 4:3 at 1440 x 1080 px, under 3 MB. Reddit recommends it for every device. For mobile-first video, use portrait 4:5 at 1200 x 1500 px.
• Reddit's own pages disagree on several limits, including image file size and video length. Build to the stricter number and you won't hit a problem.
• Free-form ads don't make a thumbnail for you. Without one, they show no media in feeds.
• One photo and video shoot, cropped five ways, covers image, video, carousel, free-form and Max campaign specs.

Reddit ad specs at a glance

Here are the core specs for each self-serve ad type, side by side. Every number comes from Reddit's ad unit specifications and the type-specific help pages linked in each section below, checked in October 2026.

The five objectives are awareness and consideration, traffic, sales, lead generation and app promotion. Our Reddit Ads guide explains how each one works and which settings you can't change later.

Feed and conversation placements, and why thumbnails matter

Every ad type can run in two placements: the feed and the conversation page. Reddit's spec overview defines them this way:

• Feed: Home, Popular and community feeds. Your ad looks different in card view and compact view.
• Conversation: the comment page of a post, which people reach from their feed or from a web search.

This matters for specs because the conversation placement and compact view often show your thumbnail, not your main image. Reddit makes a thumbnail from your media automatically for every ad type except free-form, and you can replace it. Reddit's recommended thumbnail is 400 x 300 px (4:3), JPG or PNG.

"Conversation ads" is what Reddit calls the conversation placement. Its conversation ads page says they reach people who land in threads from topic-specific searches, and that the specs depend on the underlying ad type. Reddit recommends running both placements together.

For brands that sell considered purchases, the conversation placement deserves attention. The people reading a "best e-bike under $2,000" thread are mid-research. Your thumbnail is what they see next to the comments, so it should be a clear product shot with no small text.

Image ad specs

An image ad is a headline, one image and a destination URL. Here are the full specs from Reddit's image ad specifications:

Reddit says any aspect ratio uploads, but unusual ones can cause letterboxing (bars around your image). It also suggests using one image for all devices and placements, which is why 4:3 is the safe default.

Image ads support all five objectives, and you can turn comments on or off. They're the fastest format to produce, which Reddit's ad types page lists as their main strength. Its weakness, by the same page, is that static images wear out faster than motion.

Video ad specs

A video ad is a headline and one video, MP4 or MOV, up to 1 GB, 30 frames per second, and 2 seconds to 15 minutes long. Reddit's video ad specifications recommend 5 to 30 seconds.

How the video plays depends on where it shows:

• Feed, desktop and mobile: it autoplays, unless the person has turned autoplay off.
• Conversation placement, and feeds on desktop and mobile web: Reddit's page says it plays when clicked.
• Compact view: a click goes straight to your landing page.
• Reddit app, all placements: a click opens a page with the video next to your landing page.

Because the video often autoplays without a click, the first few seconds do most of the work. Reddit's video ads page suggests building for mobile in 4:5 and keeping videos under 10 seconds. Its creative best practices also recommend adding text and captions to media.

Reddit accepts 1:1, 3:4, 4:5, 4:3 and 16:9. Keep the product and any text inside the middle of the frame so crops don't cut it off.

Carousel ad specs

A carousel is one headline and 2 to 6 images, each with its own destination URL and an optional 50-character caption. From Reddit's carousel ad specifications:

Reddit strongly recommends using the same aspect ratio for every card. Mixed ratios make the cards jump in size as people swipe.

Carousels fit considered purchases well. You can show a product's three sizes, its finishes, or the steps of a setup, and send each card to its own product page. They support awareness, traffic, sales and app promotion, but not lead generation.

Free-form ad specs

A free-form ad is a Reddit-style post with a headline and a rich-text body of up to 40,000 characters, holding up to 20 images and 5 videos. Clicking it opens the full post, where people read, watch and click any links you add. Specs from Reddit's free-form ad specifications:

Two details trip people up:

1. Add the thumbnail yourself. Free-form is the only type where Reddit doesn't make one. Without it, your ad shows no media in feeds.
2. Build it in Ads Manager. Reddit recommends creating free-form ads there, not by promoting an existing post, so the thumbnail shows as expected.

The body supports bold, italics, headings, inline links, bulleted and numbered lists, quotes, spoiler text and embedded media, according to Reddit's free-form ads guide. Reddit offers four templates: tell your story, product deep dive, the essentials and shopping guide.

For a product people research for weeks, this is the format that can hold a real answer: a comparison table, test results, sizing help, and a link to each model. The catch is that it can't run on the sales objective, so judge it on clicks and on-site behavior, not purchases.

Max campaign, product, AMA, reminder and interactive ad specs

These formats have their own rules on top of, or instead of, the specs above.

Max campaigns

Max campaigns use Reddit's AI to mix your headlines, media and calls to action for each impression, so they need more assets, not one perfect ad. Reddit's Max campaign specifications ask for:

• Headlines: 3 to 15, at least 5 recommended. Keep at least five under 50 characters.
• Media: 1 to 30 images and videos combined (up to 20 images and 10 videos), at least 5 recommended.
• Images: JPG, PNG or GIF, 10 MB, at least 1000 px wide.
• Videos: MP4 or MOV, 100 MB max (lower than the 1 GB limit for standard video ads), 5 to 30 seconds.
• Thumbnails: up to 10, JPG or PNG, 3 MB. Images without text work best.
• Calls to action: up to 5, at least 2 recommended.

Only image and video ads run in Max campaigns. Reddit asks for assets that are "meaningfully different" from each other, so five crops of the same photo won't give the system much to test.

Product ads and dynamic product ads

Product ads pull images, prices and descriptions from your catalog, so you don't upload creative for each product. Reddit's ad format by objective page recommends square 1:1 images of at least 500 x 500 px in your catalog for dynamic product ads.

Reddit's dynamic product ads page adds three setup tips: have at least 6 products in your catalog, plan to spend at least $100 per day, and expect 7 to 14 days before results show. Standard product ads let you pick which products appear; dynamic ones let Reddit choose for each person. The Reddit Pixel or Conversions API is required.

AMA ads

AMA ads promote an "Ask Me Anything" post you've already published, so the post itself is the creative. According to Reddit's AMA ads guide:

• The title can be up to 300 characters and can't be changed after you post.
• The first image in the post becomes the thumbnail and can't be cropped during ad setup.
• Custom calls to action and destination URLs aren't supported. The button changes on its own from "Remind Me" before the event, to "Join Now" while it's live.
• Only awareness and consideration or traffic campaigns are supported.
• The RSVP count shows only once 11 or more people have signed up.

If you run a community AMA, Reddit says to check the subreddit's rules first and prove your identity to the moderators. An AMA should be hosted openly by a real person from your company who can answer hard questions.

Reminder ads

Reminder ads add a "Remind Me" button to an image or video ad for a launch, release or sale date. People who tap it get a push notification and an inbox message when the event starts. Reddit's reminder ads page sets these rules:

• Headline of 25 to 50 characters recommended, because it also appears in the notification.
• Event start time between 10 minutes and 60 days after you create the ad, and it can't be changed once the ad is live.
• Awareness and consideration (impressions goal only) or traffic campaigns, Standard campaigns only.
• On traffic campaigns you pay each time someone taps Remind Me, even if they later opt out.

For a considered purchase, a reminder ad suits a pre-order date, a seasonal sale or a new model launch.

Interactive ads (beta)

Interactive ads are small apps inside an ad: a quiz, a poll or a countdown. They run only in the feed, only in Standard awareness or traffic campaigns. Reddit's interactive ad specifications list a 512 x 512 px square logo, a 4:5 mobile background at 816 x 1024 px and a 4:3 desktop background at 1400 x 1024 px, all JPG or PNG up to 3 MB.

A quiz can hold up to four questions with two to four answers each and up to four outcomes, each with its own image and link, according to Reddit's interactive ads guide. That makes a "which model fits you?" quiz a natural use for brands with several versions of a product.

Premium takeovers

Takeovers are premium packages sold through Reddit's sales team on a CPM basis, not built in self-serve. Most follow the image and video specs, with a few extra rules from the ad unit specifications page: click-through URLs must use HTTPS and can't end with a semicolon, and animated GIFs and ProRes video aren't supported.

There are three types, according to Reddit's ad types pages:

Most brands selling a considered purchase won't start here. Takeovers buy reach for a single day, while buyers of a $2,000 product often research for much longer than that.

Text limits across Reddit ad types

The headline limit is 300 characters almost everywhere, but the length Reddit recommends ranges from 25 to 100 characters depending on the ad type. This table puts every text limit from the pages above in one place:

The 268-character URL limit includes your tracking parameters, so long UTM tags can push you over. Our Reddit tracking link builder helps you keep them short.

The 23 call-to-action options on the ad unit specifications page include Learn More, Shop Now, Get Quote, Pre-order Now, Book Now, Sign Up, Visit Store and Watch Now. For an expensive product, Learn More or Get Quote usually matches what the buyer is ready to do better than Shop Now.

Reddit's creative best practices page says it studied more than 100,000 ads. It lists ten headline features linked to better conversion lift and cost per action, and says using just three of them can improve conversion rate by up to 12%. The list includes keeping it short, naming your brand, a clear call to action, a question, a time frame, a clear price and data that backs your claim. Any number you put in a headline should be one you can prove on the landing page, which our guide to keeping product claims safe covers.

Where Reddit's own spec pages disagree

Reddit publishes specs in several places, and they don't always match. Comparing the help center with Reddit's business site and its learning hub in October 2026 shows these differences:

The simple rule: build to the stricter number. A 1440 x 1080 image under 3 MB, a thumbnail under 500 KB and a video under 100 MB will pass every page's limits, and you can reuse the same files across ad types. When in doubt, the help center is the more detailed source, and Ads Manager's preview shows you the real result before you publish.

One shoot, every format: a creative kit for considered purchases

You don't need separate creative for each Reddit ad type. One shoot, exported to five sizes, covers image, video, carousel, free-form and Max campaign specs. This kit combines the stricter numbers from the comparison above:

Shoot with crops in mind. Keep the product and any text in the middle of the frame, so the 4:5, 4:3 and 1:1 crops all work. The cheat sheet from Reddit's learning hub gives the same advice: make one high-resolution master for each ratio, then check previews so nothing important gets cut.

One shoot, exported to a few sizes, gives you every file Reddit's self-serve ad types ask for.

Which Reddit ad format to use for a considered purchase

Pick the format by the job it has to do at each stage of your buyer's research. This chooser combines the objective limits above with Reddit's own "best for" notes on its ad types page:

Most brands can start with two formats: carousel or image ads on the sales objective, and a free-form post on traffic for people still comparing. Our guide to what Reddit Ads cost shows how to budget that test.

Different ad formats fit different stages: video to introduce, free-form to explain, carousel and product ads to close.

Example scenario: an e-bike brand builds its first Reddit creative kit This is an illustrative example, not a real client.

The situation: A direct-to-consumer e-bike brand with three models priced from $1,400 to $2,600 wants to test Reddit Ads. Its paid social team has square Instagram images and 9:16 videos, which don't match Reddit's recommended ratios.

What they do: They spend one day reshooting with Reddit's sizes in mind. They export six photos at 4:3 (1440 x 1080) and 4:5 (1200 x 1500), cut two 12-second 4:5 videos with captions (a hill climb and a folding demo) plus 16:9 versions, and make five 400 x 300 thumbnails with no text. They write seven headlines: five under 50 characters for testing and two under 80. They write one free-form post comparing the three models' range, weight and price, with a table and a link to each model. They launch a carousel on the sales objective with each card linked to one model, and the free-form post on the traffic objective with its own thumbnail.

The likely outcome: Every file should pass the strictest limits on Reddit's pages, so nothing is likely to be letterboxed or rejected for size, and the same kit can feed a Max campaign later. Reddit's own headline study suggests that using three of its ten headline features can improve conversion rate by up to 12%, so the team builds those into its seven headlines. Whether the test pays off depends on the budget and judging window, which our article on whether Reddit Ads are worth it covers.

Spec mistakes that get Reddit ads cropped or rejected

Most spec problems are small and easy to avoid. Check these before you publish:

1. Leaving out the free-form thumbnail. The ad shows no media in feeds without one.
2. Mixing aspect ratios in a carousel. Cards jump in size as people swipe.
3. Uploading 9:16 video. Reddit doesn't list 9:16 among its recommended ratios for standard video ads, so it may be letterboxed. Use 4:5 for mobile.
4. Using ProRes video. Reddit doesn't support it. Export to MP4 instead.
5. Mismatched display URL. The display URL must use the same domain as the destination URL.
6. Long tracking URLs. UTM tags count toward the 268-character limit.
7. Small text in thumbnails. At 400 x 300 px, it can't be read.
8. Rushing AMA titles and reminder times. Neither can be changed once live.
9. Claims you can't back up. Ads go through review against Reddit's advertising policies, and Reddit users are quick to question numbers in the comments.

If you turn comments on, someone from your team should answer them openly as the brand. Undisclosed promotion, fake reviews and vote manipulation break Reddit's rules and the FTC's endorsement guides, and buyers who spot them stop trusting the brand.

Conclusion

Reddit's ad specs are simple once they're in one place: a short headline, a URL under 268 characters, and media in 1:1, 4:5, 4:3 or 16:9, with a few extra rules for free-form, Max, AMA and reminder ads. Reddit's own pages disagree on file size and video length, so build to the stricter limits and preview every ad before you publish.

Our recommendation: shoot once for every format using the creative kit above, then start with a carousel on the sales objective and a free-form post on traffic. Write thumbnails and headlines for the conversation placement, because that's where people researching a big purchase are reading.

FAQs

What size should a Reddit ad image be?

Reddit recommends landscape 4:3 at 1440 x 1080 px for all devices. For mobile, 1:1 at 1080 x 1080 or 4:5 at 1080 x 1350 also work. Keep image files under 3 MB in JPG or PNG.

What are Reddit's video ad specs?

Reddit video ads take MP4 or MOV files up to 1 GB, at up to 30 frames per second, from 2 seconds to 15 minutes long. Reddit recommends 5 to 30 seconds. Use 4:5 at 1200 x 1500 px for mobile, or 4:3 or 16:9 for all devices.

How long can a Reddit ad headline be?

Headlines can be up to 300 characters. Reddit recommends 100 characters or fewer, and 80 if you're worried about cutoffs on some devices. For Max campaigns, keep at least five headlines under 50 characters; for reminder ads, 25 to 50.

What are Reddit conversation ads?

Conversation ads are Reddit's name for ads placed on comment pages, in and around the comment threads. They aren't a separate creative format: they use your image, video, carousel or free-form ad, often shown with its thumbnail. Reddit recommends running them together with feed ads.

What do Reddit ads look like?

Reddit ads look like regular posts marked "Promoted," with a headline, your brand's username, media and a call-to-action button. People can upvote and comment on them if you turn comments on. Free-form ads look the most like normal Reddit posts, with long text, images and links.