Video aspect ratio and resolution calculator
Three calculations you need every day: the ratio of a resolution, the height that matches a width, and how many pixels to cut from each side to crop a 16:9 into vertical.
Ratio of a resolution
The missing dimension
Crop from one format to another
Results are rounded to even pixels: H.264 and H.265 encoders reject odd dimensions.
Cropping without guessing
Turning 1920 × 1080 into 9:16 isn't stretching the image: you keep the height (1080) and cut the width down to 608 pixels, which means 656 pixels lost on each side. That's huge: anything off-centre disappears. Hence the habit, on set, of framing a little wide and leaving air around the subject when a vertical version is coming.
In Premiere, you crop by dropping the clip into a 1080 × 1920 sequence and adjusting position and scale — the 656 px computed here tell you exactly how far you can move the frame before running out of image.
Formats per platform
| Platform | Resolution | Ratio | Frames/s | Max length |
|---|---|---|---|---|
| YouTube (landscape) | 1920 × 1080 to 3840 × 2160 | 16:9 | 24 to 60 | 12 h |
| YouTube Shorts | 1080 × 1920 | 9:16 | 30 or 60 | 3 min |
| TikTok | 1080 × 1920 | 9:16 | 30 or 60 | 10 min |
| Instagram Reels | 1080 × 1920 | 9:16 | 30 | 3 min |
| Instagram (feed) | 1080 × 1350 | 4:5 | 30 | 60 min |
| 256 × 144 to 4096 × 2304 | 1:2.4 to 2.4:1 | 10 to 60 | 15 min | |
| X (Twitter) | 1920 × 1080 | 16:9 | 30 or 60 | 2 min 20 |
What was checked, and what wasn't. The LinkedIn row comes from the official help page "Supported video file formats on LinkedIn", read on 26 September 2026: 256 × 144 to 4096 × 2304, ratio 1:2.4 to 2.4:1, 10 to 60 frames per second, 15 minutes and 5 GB maximum, 192 kbps to 30 Mbps. YouTube's recommended bitrates live in our bitrate calculator, read the same day on "Recommended upload encoding settings".
The other rows (YouTube Shorts, TikTok, Instagram, X) are common working values, not automatically verified on 26 September 2026: those help pages are rendered in JavaScript and can't be read by a script. Before a client delivery, open the platform's own help page — they change without notice.
Frequently asked questions
Why are results rounded to even numbers?
Because H.264 and H.265 encoders work in blocks and reject (or silently fix) odd widths and heights. 607 becomes 608: one extra invisible pixel row, and an export that doesn't fail.
21:9 or 64:27, which one is right?
Both. 2560 × 1080 mathematically reduces to 64:27; "21:9" is the marketing name of that family of wide formats. The tool shows the exact reduction and the common name when one exists.
Is 2.39:1 the cinema format?
Yes, that's modern scope, the widescreen film format. You get it either with an anamorphic lens on set, or by cropping: the tool tells you how many pixels to cut top and bottom.
Should I export in 4K for YouTube?
Not necessarily, but a 1440p or 2160p upload gets a more generous encode from YouTube, even when watched in 1080p. It's the old trick of channels that care about image: it costs upload time, not quality.
Are these platform numbers current?
The LinkedIn row was read from the official help page on 26 September 2026. The others are common working values our automated check couldn't confirm that day, and it says so under the table. Before an important delivery, read the platform's help page.
Are my dimensions sent anywhere?
No. Everything is computed in the page, with no network request.