Glossary
What are Facebook Reels?
Facebook Reels are short, vertical videos. Meta’s Reels publishing API can post them to Facebook Pages, and its documentation sets the technical rules: 3 to 90 seconds, 9:16, and a cap of 30 API-published Reels per 24 hours. Here is what that means.
Updated 6 October 2026
Short vertical videos on Facebook. Through Meta’s API they can be published to Pages only, at 3 to 90 seconds, in a 9:16 ratio.
What the publishing documentation says
These are the specs in Meta’s Reels publishing guide for developers, read on 6 October 2026. They describe publishing through the API. The app itself may accept other lengths or formats, so check your own app before assuming the same limits there.
| Spec | Meta’s documentation |
|---|---|
| Where you can publish | Facebook Pages only |
| Length | 3 to 90 seconds |
| Aspect ratio | 9 x 16 |
| Resolution | 1080 x 1920 pixels recommended; minimum 540 x 960 |
| File format | .mp4 recommended |
| Frame rate | 24 to 60 frames per second |
| Audio | Stereo, AAC codec, 48 kHz sample rate, 128 kbps or more |
| Daily cap | 30 API-published posts in a 24-hour moving window |
| Collaborator invites | 10 per Page per 24 hours |
Publishing needs a Page access token and permissions that include pages_manage_posts. The guide says Reels can be published only to Pages, so the person connecting needs a suitable role on the Page.
Why it matters
- If you make one vertical video for several apps, 9:16 at 1080 x 1920 is the size Meta recommends here.
- Anything under 3 seconds or over 90 is outside the documented range for API publishing.
- The 30-a-day cap matters if a scheduling tool posts for many clients through one Page. One Page rarely needs more.
- Comments on Reels arrive on a Page, so the Page’s inbox and comment tools are where replies happen.
Tip: Export once at the recommended size, then check how the first Reel looks in the app before you batch a month of posts.
Reels on Facebook and on Instagram
Both apps have a Reels format and the specs sound alike, but they are separate products with their own rules. We did not read an official page comparing them, so check each app. DMFast’s comment-to-DM works on Instagram Reels comments for professional accounts; this page makes no claim about Facebook Reels comments in DMFast.
An example
A cafe films a 25-second vertical clip of latte art at 1080 x 1920, exports it as an .mp4 and has a scheduling tool publish it to its Facebook Page. That sits inside every spec in the table.
Questions people ask
What are Facebook Reels?
They are short vertical videos on Facebook. Meta’s documentation describes them as vertical video content that can be published to Facebook Pages through an API, with a 9:16 aspect ratio.
How long can a Facebook Reel be through the API?
Meta’s Reels publishing guide says 3 to 90 seconds. The app may allow other lengths, and Meta can change this, so verify against the live documentation or your own app.
Can I publish Reels to a personal profile with the API?
The documentation says you can only publish Reels to Facebook Pages. The person publishing needs a Page access token and permissions including pages_manage_posts.
Is there a limit on how many Reels I can publish by API?
Yes. The documentation says 30 API-published posts within a 24-hour moving window. Collaborator invitations are capped at 10 per Page per 24 hours.
Sources
Related terms
- Facebook PageA public Facebook presence for a business, brand or creator, managed by people with roles. It is separate from a personal profile and is what messaging tools connect to.
- Page rolesThe levels of access people can hold on a Facebook Page: Admin, Editor, Moderator, Advertiser and Analyst, from full control down to viewing reports.
- ReachReach is the number of unique accounts that saw a post, Reel or Story at least once. An account that sees it again doesn’t add to it.
- Facebook groupA community space on Facebook where members post and talk around a topic, run by admins and moderators. A Page is different: it is a brand’s public presence.
- Instagram algorithmThe ranking systems that decide what each person sees on Instagram. Instagram says there is no single algorithm: Feed, Stories, Explore and Reels each rank differently.
- Content calendarA schedule of the posts, Reels and Stories you plan to publish, with the date, format, caption and goal for each, so your account does not run on last-minute ideas.
More terms
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