Aspect Ratio Calculator for Video
Enter any width and height — get the simplified ratio, and the exact pixel dimensions to convert between 16:9 long-form and 9:16 vertical without guessing.
The two ratios that run the creator economy
Modern video life happens in exactly two shapes: 16:9 horizontal (YouTube long-form, streams, most cameras' native output) and 9:16 vertical (Shorts, Reels, TikTok — the phone held the way phones are held). Every other ratio you'll meet — 4:3 legacy footage, 1:1 feed squares, 21:9 cinematic — is an import from another era or platform. This calculator names whatever you feed it and computes the exact pixels to move between the two shapes that matter, because 'roughly vertical' produces the letterboxed, half-cropped uploads that scream amateur in a feed.
Converting without casualties
The brutal math of 16:9 → 9:16: the vertical crop keeps only about a third of your horizontal frame's width. Whatever lives at the edges — second subjects, on-screen text, the whiteboard you gestured at — dies in the conversion. Two workflows survive it. Shooting for both: keep your subject and any critical text inside the center ~35% of the horizontal frame, and the vertical crop costs nothing. Reframing per shot: modern editors (and their auto-reframe features) let the crop window follow the action shot by shot — slower than a static center-crop, and the entire visible difference between a Short that feels native and one that feels salvaged.
The pixel targets worth memorizing
Long-form: 1920×1080 remains the standard delivery, 3840×2160 for 4K masters. Vertical: 1080×1920 everywhere — Shorts, Reels, and TikTok share the spec, which is why one export serves all three (strip platform watermarks before cross-posting; platforms deprioritize each other's branding). Thumbnails: exactly 1280×720 under 2MB per YouTube's spec — a 16:9 frame you should design at phone-feed size, where it actually gets judged. When exporting an unusual source (screen recordings, phone footage, game captures), run it through this calculator first: matching your sequence settings to the source's true ratio prevents the subtle stretch that viewers can't name but always notice.
Frequently asked questions
What aspect ratio is YouTube?
16:9 for long-form (1920×1080 standard, 3840×2160 for 4K) and 9:16 for Shorts (1080×1920). The player adapts to other ratios with letterboxing, but native 16:9 or 9:16 uses the full frame — and the full attention — of each surface.
What resolution should YouTube Shorts be?
1080×1920 (9:16) — the same spec Reels and TikTok use, so one vertical export serves all three platforms. Vertical video up to 3 minutes qualifies as a Short; the ratio, not just the length, is what routes it to the Shorts feed.
How do I convert 16:9 video to 9:16?
The vertical crop keeps only ~a third of your horizontal width, so either shoot with subjects centered (critical content inside the middle 35%) or reframe per shot so the crop follows the action. This calculator gives the exact pixel targets; auto-reframe features in modern editors handle the per-shot tracking.
What size should a YouTube thumbnail be?
1280×720 pixels (16:9), under 2MB, per YouTube's published spec. Design it at the size it's judged — a phone feed where it renders about 5cm wide — not at your monitor's full resolution.
Why does my video have black bars?
Letterboxing appears when your video's ratio doesn't match the player: 4:3 footage in a 16:9 player gets side pillars, horizontal video viewed in the Shorts feed gets top-and-bottom bars. Fix it at export by matching your sequence to the target ratio — this calculator computes the exact dimensions.
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