About the Image Dimension Checker tool
Instantly read an image's width, height, aspect ratio, megapixels, and file size — without opening an editor or uploading anything.
This runs entirely on your device. Photos often carry more private information than people realize, so keeping them off a server is the sensible default.
How to use it
- Add your image.
- Read the width, height, aspect ratio and file size.
- Compare against whatever requirement you are trying to meet.
Pixels, aspect ratio and file size are three different things
Width and height are the pixel dimensions. Aspect ratio is the relationship between them. File size is how much disk space the compressed data occupies — and it is only loosely related to the other two.
Upload forms frequently mix these up in their wording, which is why 'image too large' can mean either dimensions or kilobytes. Checking all three at once tells you which limit you have actually hit.
Reference sizes
- Instagram post: 1080 × 1080 (1:1) or 1080 × 1350 (4:5)
- YouTube thumbnail: 1280 × 720 (16:9)
- Facebook cover: 851 × 315
- Social link preview: 1200 × 630 (1.91:1)
- Favicon: 32 × 32 and 180 × 180
Common mistakes
- Assuming 'too large' always means file size. Often it means dimensions.
- Reading dimensions from a thumbnail preview rather than the file itself.
- Ignoring aspect ratio, which is what causes unexpected cropping on social platforms.
Questions people ask
What is aspect ratio?
The proportional relationship between width and height. 1920 × 1080 and 1280 × 720 are both 16:9, so both fit the same frame without cropping.
Why does my image get cropped when I upload it?
Its aspect ratio does not match what the platform expects, so it trims the excess.
Does this work on any format?
Yes — JPG, PNG, WebP, GIF, AVIF and anything else your browser can render.