Posting Video on Instagram: Reels Specs
Reels redefined what Instagram video is: vertical, short, watched muted. Specs matter, but so do cover frames and burned-in captions — publish strategy decides reach as much as encoding does.
Reels specs and content shapes
Reels is 9:16 vertical (1080×1920) territory with a 90-second ceiling — some accounts have been widened to 3 minutes; trust the in-app prompt. Feed video accepts both orientations up to 60 minutes; Stories run in 15-second segments. Three entry points, three content shapes — pick the entry first, then the specs.
Worth a separate note: 4:5 (1080×1350) takes up noticeably more feed real estate than 1:1 for in-feed video. Reels is strictly 9:16. Do not force one master file onto every entry point.
Encoding and the re-encode margin
H.264 + AAC is the safe pairing. Start at 1080p 30fps (60 is supported but 30 is enough in-feed) and give the source 8–12 Mbps. Instagram re-encoding is among the most aggressive of major platforms — a generous source bitrate is the only way to leave the transcoder something to work with.
Get size and aspect right locally before uploading: pre-compress to the target bitrate, and crop mismatched framing yourself rather than trusting the platform letterboxing. A clean source is the cheapest insurance against double-generation loss.
Covers and the muted feed
Reels lets you pick a cover frame — in the grid, the cover is the click. Choose an action peak or a text-bearing frame, not an arbitrary first frame. The feed autoplays muted: without a visual hook in the first 3 seconds viewers scroll past, and burned-in captions are the only information channel that survives silence.
Reels distribution runs on completion rate and engagement. Cutting a tight standalone clip beats stuffing a long video into 90 seconds.