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
Enter your values
See the result update instantly
Use it to plan or resize your video
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.
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.
Always scale both dimensions by the same ratio. This calculator does the math so the new size matches the original proportions exactly.
Yes — it runs entirely in your browser, needs no sign-up, and is completely free to use as often as you like.
Free, fast tools to compress, convert, trim and clean up your videos — no sign-up.