Instagram's Reels page says 3 and 20 minutes: which one to plan for

Plan the creative for 3 minutes and the tooling for 20. The page I read says two things about length: an overview line about creating multi-clip videos up to 3 minutes, and an FAQ line that you can record one or more clips adding up to 20 minutes, with Reels over 3 minutes not recommended to new audiences (read 2026-10-07). They are not a contradiction if you read the recommendation as the real ceiling for reach.

That gives you one decision rule, and it maps cleanly onto the caps in Sume's own tools.

The two numbers and what each means for you

From Instagram's Reels page. I could not read Instagram's help-center pages with my fetch tool, so I do not state aspect-ratio, frame-rate, or file-size rules here.

How Sume's caps line up

The tools sit comfortably inside both numbers. Timeline 1.0 renders up to 1,800 seconds (30 minutes) and its default output is 1080x1920. Video trim outputs up to 900 seconds (15 minutes). So a 20-minute Reel is 1,200 seconds: possible to assemble in Timeline, but not as one trim output.

limits = {"reach_target_s": 180, "instagram_max_s": 1200, "trim_out_s": 900, "timeline_s": 1800}
for name, seconds in limits.items():
    print(name, seconds, "s =", seconds / 60, "min")
print("20-minute Reel fits one trim output:", limits["instagram_max_s"] <= limits["trim_out_s"])
print("20-minute Reel fits one timeline:", limits["instagram_max_s"] <= limits["timeline_s"])

A rule of thumb

If the piece is a single idea, make it under 3 minutes and render it in one Timeline job. If it is a lesson, a talk, or a recording that needs the full run, publish the long form for your followers and cut a 3-minute version for new viewers using video trim with a start and duration of at most 180.

Two files, two uses. That is a media decision; Instagram's page does not tell you the long Reel will do worse for your followers, and I will not claim it.

Probe before you publish

Run video inspect on the final file and read duration_seconds. A file at 181 seconds is over the 3-minute line the page names, and a probe is the quickest way to see that before the upload screen does.

A note on what I could not read

Instagram's help-center pages (aspect ratio, resolution, frame rate) did not load in my tools, and one search snippet cited limits I could not verify on the page itself. I left them out. If you need those numbers, open the help center directly and keep a dated copy.

The features page is marketing copy as much as spec, and its wording can change. Date your notes, as the tables here do, and re-read before a campaign that depends on a limit.