Platforms expect specific shapes. Instagram likes squares and 4:5 portraits, YouTube thumbnails are 16:9, and print sizes follow their own ratios. Locking the crop box to a ratio takes the guesswork out.
Why aspect ratio matters
If you upload the wrong shape, the platform crops it for you, often cutting off the part you cared about. Cropping to the right ratio yourself means you decide what stays in frame.
Common ratios and where they go
- 1:1 square: profile pictures, Instagram grid posts.
- 4:5 portrait: Instagram feed posts that take more vertical space.
- 9:16 tall: stories, Reels, TikTok, Shorts.
- 16:9 wide: YouTube thumbnails, presentation slides, video frames.
- 3:2 and 4:3: classic photo and print proportions.
How to crop to a ratio
- Open Crop to Aspect Ratio.
- Add your image and pick a ratio.
- Move the locked box over the part you want to keep.
- Apply and download.
Finish for the platform
For social specifically, the dedicated resizers like the Instagram Post Resizer or YouTube Thumbnail Resizer set both the ratio and the exact pixel size in one step.
Frequently asked questions
What aspect ratio is best for Instagram?
1:1 square works everywhere, while 4:5 portrait gives your post more vertical space in the feed.
What ratio is a YouTube thumbnail?
16:9, usually at 1280 by 720 pixels.
How is aspect ratio different from resizing?
Aspect ratio is the shape of the image. Resizing changes the actual pixel dimensions. You often crop to a ratio first, then resize to exact pixels.