Instagram Reels specs in 2026: size, length, cover and caption limits

Export Reels as 1080×1920 MP4 or MOV files with H.264 or HEVC video and AAC audio, between 3 seconds and 15 minutes long and under 300 MB. Two things trip people up more often than the file: the index has to sit at the start of the file, and if you don't set a cover, Instagram uses your first frame.

Instagram Reels video requirements

These limits are from Meta's Instagram API reference, which applies when a Reel is published by a scheduling tool rather than from the Instagram app:

The 1920-pixel limit is on width ("maximum columns"). A vertical 1080×1920 file is fine; a landscape 4K file (3840 pixels wide) is not, even though it is a perfectly normal export.

The fast-start rule

"Moov atom at the front of the file" means the index that tells a player where each frame is stored comes before the video data. Many editors write it at the end, which plays fine on a computer but can fail on Instagram's side. In most exporters this is a checkbox called "fast start" or "optimise for web"; in ffmpeg it is -movflags +faststart. The full export command that fits Instagram and every other network is in our social media video specs overview.

The cover image

When a Reel is published through the API without a cover, Instagram uses the frame at thumb_offset, which defaults to 0 — the very first frame. If your video starts with a fade from black, a title card or a blurred transition, that is what appears on your profile and in the Reels tab.

A separate cover avoids it. Meta's rules for the cover image:

• Format and size: JPEG, up to 8 MB.

• Aspect ratio: 9:16 recommended. Other ratios are cropped to the middle 9:16 rectangle.

• Profile grid: if the Reel is shared to your feed, Instagram crops the middle square of the cover for the feed post.

• Priority: when both a cover image and a frame offset are set, the cover image wins.

Design the cover so the important part — a face, a title — sits in the centre square. Text near the top or bottom edge survives in the Reels tab and disappears in the grid.

Feed and Reels tab: what "share to feed" means

A Reel published with share_to_feed set to true can appear in both the Feed and the Reels tab; set to false, only in the Reels tab. Meta adds one caveat worth knowing: neither setting guarantees the Reel actually shows in the Reels tab, because it "may not meet eligibility requirements or may not be selected by our algorithm."

Caption, hashtag and mention limits

Only the first line or two of a caption shows under a Reel before "more", so the hook belongs at the start and the hashtags at the end. How the limits compare across networks is in social media character limits.

How many Reels can you publish per day?

Instagram limits API-published posts per account in a rolling 24-hour window, and a carousel counts as one post. Meta's own content publishing page currently gives two numbers: the main limit section says 100 API-published posts, while the carousel section says 50 published posts. Until Meta settles it, plan on 50 to be safe — far more than any account should post anyway. Developers can check an account's current usage with the content_publishing_limit endpoint.

API publishing also needs an Instagram professional account; a personal account can't be connected to a scheduling tool for publishing.

Before you schedule a Reel

• 1080×1920, H.264, AAC 48 kHz, 30 fps, fast start, under 300 MB.

• Between 3 seconds and 15 minutes.

• A cover image with the key element in the centre square — or a strong first frame.

• Text kept out of the bottom fifth and the right edge, where Instagram's caption and buttons sit (safe zones).

• Caption hook in the first line, hashtags at the end, at most 30.

Our video spec checker tests length, size, resolution and container in your browser. When Uplonic publishes a Reel, it sends the video's thumbnail as the cover image; if Instagram can't fetch that image, it retries once without a cover so the Reel itself still goes out.