幻燈片影片的畫面比例速查指南。

16:9 — the default for screens

Sixteen-by-nine is the lingua franca of video. It's what YouTube, Vimeo, televisions, projectors, and most desktop monitors are shaped like. If a video might ever be played in a player chrome or on a screen larger than a phone, 16:9 is the safe choice. Conference talks, tutorials, establishing-shot reels, behind-the-scenes recaps — anything that wants to feel like film or broadcast lives here.

The catch: 16:9 is wider than most cameras shoot. If you crop a 3:2 DSLR frame to 16:9 you lose roughly 17% of the height. Decide before the shoot whether you can sacrifice that headroom, or compose with it in mind.

9:16 — vertical, by necessity

Vertical isn't a style choice anymore; it's where people watch. Instagram Reels, TikTok, YouTube Shorts, WhatsApp Status, Snapchat — all of them serve 9:16 full-bleed. A horizontal video uploaded to a vertical surface gets letterboxed into a tiny strip and ignored.

If you shot horizontal frames and need a vertical video, you have two honest options: crop into the subject (and lose context), or fill the vertical canvas with a blurred copy of the image behind a centered, contained version. The second looks reflexively professional and is what most social teams default to. The first is sharper and braver.

1:1 — square, for the grid

Squares had their moment when Instagram only allowed them. They're still useful when you don't know where the video will play, or when you want it to look at home in a feed grid alongside still photos. A 1:1 video also wastes less of a phone screen than a 16:9 video does, while still working on a desktop.

Treat 1:1 as a compromise format. It's rarely the most expressive choice, but it travels well.

4:5 — portrait, for feeds

Four-by-five is the tallest aspect Instagram allows in its main feed (anything taller gets cropped at preview). It's the modern default for portrait social posts that want to dominate the screen without committing fully to a 9:16 story format. Photographers shooting medium format will recognise it — 4:5 has been the standard print ratio for a century.

For slideshow video on a feed-first platform, 4:5 is almost always the right answer.

3:2 — native to the camera

Most DSLR and mirrorless cameras shoot 3:2. If your source images are uncropped camera files and you don't have a target platform in mind, 3:2 is the laziest correct choice — it preserves what you actually photographed. A 3:2 video looks at home on a website, in a portfolio PDF, or as an attachment in an email.

Avoid 3:2 for social platforms; it sits awkwardly between 4:5 (portrait) and 16:9 (landscape) and ends up letterboxed in both directions.

The mixing problem

The temptation, when you have a folder of mixed-orientation images, is to throw them all in and let the player handle the rest. Don't. A single mixed-orientation video creates one of two problems:

Either you commit to a single canvas aspect and the portrait frames get heavy letterboxing on the sides (or landscape frames on the top and bottom). Or you mix-and-match crops and the video feels jittery — every cut shifts the visual centre of the frame.

The fix is to standardise before you sequence: crop every image to the same aspect first, then compose the timeline. That's the workflow our companion tool Aspect Crop is built for. Drop your mixed-orientation folder, pick a target ratio, and the cropped set comes out ready for shotseq.

A quick decision flow

If you only remember one thing from this piece, remember the flow:

Where will it play? Phones first -> 9:16 or 4:5. Web or feed -> 16:9 or 4:5. Mixed contexts -> 1:1. What did you shoot? Vertical phone frames -> keep them 9:16. Horizontal camera frames -> 16:9 or 3:2. Will you mix orientations? Crop first. Always crop first.

The aspect ratio you pick is doing more work than transitions, music, or pacing. It decides where the eye lands, how the work feels on the device that will play it, and how seriously the viewer takes the first frame. Pick early, pick deliberately — and you'll spend the rest of the edit on what actually matters.