Schedule Instagram Reels ahead of time

How Reels work when you schedule them

When a video is published through Instagram's content publishing API, Instagram publishes it as a Reel; there is no separate feed-video option in the API. Postika publishes through that API, so a video you schedule on an Instagram channel goes out as a Reel.

What Postika does not control is how Instagram treats the Reel afterwards (where it is recommended, whether it appears in the Reels tab for non-followers). That depends on Instagram, mostly on the video itself: vertical 9:16, good quality, original audio or audio you have the rights to.

Two limits of the format worth knowing:

• A Reel is one video. Reels cannot be part of a carousel.
• Instagram's API does not support alt text on Reels, only on images.

Reel specs that pass Instagram's API

The table above lists the official values. In practice:

• Ratio: 9:16 vertical. Other ratios are accepted but will not fill the screen.
• Length: 3 seconds to 15 minutes. Short Reels (under a minute) are what most brands schedule.
• File: MP4 or MOV, up to 300 MB, at most 1920 pixels on the long side.
• Codec: H.264 or HEVC video, AAC audio, 23 to 60 frames per second.

If an upload fails on Instagram's side, the most common causes are a file over 300 MB or an unusual codec from a screen recorder. Re-export with your editor's "Instagram" or "H.264" preset.

Captions for Reels

People watch a Reel before they read its caption, so the caption's job is different from a photo post: add context, a question or a call to action, not a repeat of the on-screen text. Keep the first line under a hundred characters or so, since that is what shows under the video.

Instagram's API accepts up to 30 hashtags and 20 mentions per caption. Three to five relevant hashtags are usually enough. Draft and check caption length in the character counter.

One clip, three networks

A vertical video works on Instagram Reels, TikTok and YouTube Shorts. In Postika you can select all three channels for one post, or create three posts at different times with captions adapted to each audience. Watch the limits: YouTube treats vertical videos up to 3 minutes as Shorts, while Instagram accepts Reels up to 15 minutes.

Writing Reel captions with your AI

Connect Claude or ChatGPT to Postika and ask it to prepare the week's Reel captions. Because the video cannot be sent over MCP, the AI creates each Reel as a draft or pending post on the right day; you open it in Postika and upload the clip. Example: "Create three Instagram drafts for Tuesday, Thursday and Saturday at 19:00 with captions for our behind-the-scenes Reels, under 150 characters each." See Claude for Instagram.