Free publishing tool
Aspect ratio calculator for video and images
For anyone exporting a graphic or a video for a feed and wanting it to arrive uncropped. Pick a platform ratio and type one side to get the other, or enter the pixel size of a file you already have to see which ratio it really is, including the near-misses an export pipeline produces.
Editing either field recalculates the other at 9:16. Used for reels, tiktok, shorts, stories.
Calculated in your browser. A ratio tells you the shape, not the export size: check the platform's current pixel and file-size guidance before you upload, and keep text away from the edges where a feed may crop.
The arithmetic, with real sizes
Resizing to a ratio is one multiplication: the missing height is the width times the ratio's second number, divided by its first. For 9:16 at a width of 1080, that is 1080 × 16 ÷ 9 = 1920. For 4:5 at the same width, 1080 × 5 ÷ 4 = 1350. Going the other way, a height of 1350 at 4:5 gives a width of 1350 × 4 ÷ 5 = 1080. The calculator rounds to whole pixels, because a file cannot have half of one.
Finding the ratio of a size you already have means dividing both sides by their greatest common divisor. 1920 by 1080 share a divisor of 120, which leaves 16:9. That works for clean sizes and fails for real ones, so the calculator also reports the nearest platform ratio within one percent:
| Size you enter | Exact reduced ratio | Nearest platform ratio | Why it matters |
|---|---|---|---|
| 1920 × 1080 | 16:9 | 16:9, exact | A clean export |
| 1080 × 1349 | 1080:1349 | 4:5, within 1% | One pixel lost in an export; most feeds will still treat it as 4:5 |
| 1200 × 630 | 40:21 | 1.91:1, within 1% | The Open Graph size Meta asks for is not exactly 1.91:1, and does not need to be |
| 3024 × 4032 | 3:4 | 4:5 is the nearest, and not a match | A phone photo in portrait; a 4:5 feed will crop it |
Ratio is the shape, size is the resolution
A ratio describes proportions and nothing else. 1080 by 1920 and 720 by 1280 are both 9:16, and both will fill a phone screen without cropping; one is simply sharper than the other. Confusing the two is what produces an export that fits perfectly and looks soft.
Get the ratio right first, because that is what decides whether a feed crops your image. Then pick a resolution high enough that the platform's own compression has something to work with, which in practice means exporting at least as large as the largest surface the image will appear on.
The ratios each platform documents
| Platform or surface | Ratio | What the documentation says |
|---|---|---|
| Reels, TikTok, Shorts, Stories | 9:16 | Full phone screen; the app draws its buttons and caption over the lower and right edges |
| Instagram feed, portrait | 4:5 | The tallest a feed post is shown without cropping |
| LinkedIn link posts | 1.91:1 | 1200 × 627 for link images, which the calculator's 1.91:1 preset rounds to 1200 × 628 |
| Facebook and most link cards | 1.91:1 | An Open Graph image of at least 1200 × 630, as close to 1.91:1 as possible |
| Threads | Up to 10:1 | Width between 320 and 1440 pixels, and no image wider than ten times its height |
| Telegram photos | Up to 20:1 | Width plus height up to 10,000 pixels through the Bot API |
Leave room for the crop you did not plan for
- Keep text and faces away from the outer ten percent. A feed that crops a 4:5 image to a square takes it from the top and bottom.
- A 9:16 video gets interface drawn over it. Captions, the username, and the action rail all sit on top of the lower and right edges.
- Export one 1:1 and one 9:16 rather than a folder of per-platform crops. Those two cover most destinations, and a 4:5 covers the rest.
- Check the exported file, not the design canvas. The 1080 × 1349 row above is what a rounding step in an export pipeline looks like.
Questions about aspect ratios
How do I calculate the height for a 9:16 video?
Multiply the width by 16 and divide by 9. A 1080-pixel-wide video needs a height of 1920, and a 720-pixel-wide one needs 1280. Type the width into the Ratio to dimensions tab with 9:16 selected and the height fills in.
What ratio is 1080 by 1350?
Exactly 4:5. Both numbers divide by 270, leaving 4 and 5. It is the portrait size most people use for Instagram feed posts, because 4:5 is the tallest ratio the feed shows without cropping.
Is 1200 by 630 the same as 1.91:1?
Close, not identical. 1200 by 630 reduces to 40:21, which is about 1.905:1, and LinkedIn's 1200 by 627 is about 1.914:1. Both are well within one percent of 1.91:1, which is the tolerance that matters for a link card, so use whichever size the platform you care about most publishes.
Why does my phone photo get cropped on Instagram?
A phone photo in portrait is usually 3:4, for example 3024 by 4032, which is taller than the 4:5 the feed allows. Instagram makes you crop it to fit, and the default crop takes from the top and bottom. Crop it to 4:5 yourself before uploading and you decide what is lost.
Does a higher resolution change the aspect ratio?
No. 720 by 1280 and 2160 by 3840 are both 9:16. Resolution decides how sharp the file looks after the platform compresses it; the ratio decides whether it is cropped.
Related tools
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