Aspect ratio calculator
Turn one video's dimensions into the exact crop for 9:16, 1:1, 4:5, and 16:9.
- 100% free
- No sign-up
- Private — runs in your browser
- No file limits
- Source ratio
- 1.778 : 1
- Crop size
- 608×1080px
- Crop offset (x, y)
- 656, 0px
- Recommended export
- 1080×1920px
How to use it
- 1Enter your source video's width and height.
- 2Pick the target ratio for the platform you are posting to.
- 3Switch between “Crop to fill” and “Fit” to compare.
- 4Use the output size, offset, and recommended export resolution in your editor.
About this tool
One video almost never fits every platform — TikTok and Reels want tall 9:16, the feed likes 1:1 or 4:5, and YouTube stays at 16:9. This calculator takes your source dimensions and works out exactly how to reframe them. “Crop to fill” gives the largest centred crop at the new ratio, plus the pixel offset to position it; “Fit” adds letterbox padding so nothing is cut. It also suggests a clean export resolution for each ratio.
Frequently asked questions
What's the difference between crop and fit?
Crop to fill keeps the frame full but trims the edges to reach the new ratio. Fit keeps the whole frame and adds bars (letterboxing) instead. Crop looks best for full-screen vertical video; fit is safer when content near the edges matters.
What export resolution should I use?
The tool suggests a standard one per ratio — 1080×1920 for 9:16, 1080×1080 for 1:1, 1080×1350 for 4:5, and 1920×1080 for 16:9 — which every platform accepts.
Does this resize my video for me?
No — it does the math and shows the numbers. Plug the crop size, offset, and export resolution into your editor (Premiere, CapCut, Final Cut, and so on) to apply it.
Skip the busywork entirely
These tools handle the fiddly bits by hand. Yelly Nelly does the whole thing — upload one video and it writes captions and posts to all 22 platforms in a click.
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