Resizing for a new platform without distorting your video means keeping the aspect ratio exact. Enter one dimension and a ratio and this free aspect ratio calculator gives you the other side instantly — handy for 16:9 YouTube, 9:16 Reels and TikTok, 1:1 feed posts and 4:5 portraits.
Height for a 16:9 video at 1920px wide
How it works
Enter your values
See the result update instantly
Use it to plan or resize your video
Frequently asked questions
What is an aspect ratio?
An aspect ratio is the proportion of width to height — for example 16:9 (widescreen) or 9:16 (vertical). Keeping it consistent stops your video from looking stretched or squashed.
What aspect ratio should I use?
Use 16:9 for YouTube and landscape, 9:16 for TikTok / Reels / Shorts, 1:1 for square feed posts, and 4:5 for portrait feed posts.
How do I keep quality when resizing?
Always scale both dimensions by the same ratio. This calculator does the math so the new size matches the original proportions exactly.
Is this calculator free?
Yes — it runs entirely in your browser, needs no sign-up, and is completely free to use as often as you like.
A Free Aspect Ratio Calculator
This is how to work out video dimensions instantly: enter a width or a height and a target ratio, and the calculator gives you the matching size. Browser-based and free, with a watermark-free result.
Get the exact pixel dimensions for 16:9, 9:16, 1:1, 4:5 or any custom ratio — so your video or image fits the platform without stretching or guesswork.
Calculate Any Aspect Ratio
Whether you're sizing a video for YouTube (16:9), a Reel (9:16) or a feed post (1:1 or 4:5), this calculator gives the exact width and height from a single number — no math, no trial and error.
Enter one dimension, get the other.
16:9, 9:16, 1:1, 4:5 and custom
Enter width or height
Exact pixel dimensions out
Size Video and Images Right
Wrong dimensions mean black bars or a cropped subject. Use the calculator to plan the right size before you export, so the video fits its placement perfectly.
Plan the size, avoid the crop.
Free and Instant
No download, no sign-up — the aspect ratio calculator works instantly in the browser on any device.
Just enter and read the result.
Everything the Aspect Ratio Calculator Does
Who Uses the Aspect Ratio Calculator?
Anyone sizing video or images:
Calculate, Then Make Your Video
Vivideo is more than a calculator — generate, edit and resize video, all in one place.
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Make a Video at Any Ratio
Generate or resize a video to the exact aspect ratio you need — free on Vivideo.