Image Dimensions Checker
Read an image’s width, height, aspect ratio, format and file size straight from its header, without decoding the pixels.
How it works
- Drop in one image or a whole folder — JPEG, PNG and WebP dimensions are read straight from the file header.
- Each image gets a row: format, width, height, simplified aspect ratio, megapixels, file size and orientation.
- A file that cannot be read gets its own error row — the rest of the batch still reports.
Frequently Asked Questions
How does it read the size without opening the image?
Dimensions live in the file header — the IHDR chunk in PNG, the frame header in JPEG, the VP8 chunk in WebP — so only the first few bytes are needed. Nothing is decoded, which is both faster and safer.
Why does that matter for safety?
A small file can declare enormous dimensions. A 2 MB PNG claiming 30000 × 30000 pixels would need about 3.6 GB of canvas memory and would kill the tab. Reading the header first means such a file is rejected with a message instead.
What is the aspect ratio shown as?
Both as a simplified integer ratio, so 1920 × 1080 reports 16:9, and as a decimal for cases that do not reduce neatly.
Which formats are supported?
PNG, JPEG and WebP dimensions are read from the header. GIF, BMP, AVIF, ICO and SVG are identified by format, but their dimensions are not always available from the header alone, and the tool says so rather than guessing.