Image File Inspector
Check an image’s format, file size, pixel dimensions and aspect ratio in your browser before you upload it somewhere.
Choose an image
Read locally. Nothing leaves this device.
Compared as 1 KB = 1024 bytes.
Result
No file chosen yet.
The details appear here.
Your file is never sent to a server. It is read and processed by your own browser, and the results are not stored.
How to use it
- Choose an image or drag it onto the drop area.
- Read the reported format, file size and pixel dimensions.
- Optionally enter a maximum file size to see whether the image would pass.
Limits worth knowing
- Files above 25 MB are not opened. That ceiling is checked before any decoding work, so an oversized file fails fast instead of freezing the page.
- Images above 20 megapixels, or wider or taller than 8,192 pixels, stop the tool before it decodes anything. It quotes the size found in the header and explains why it stopped, rather than building a preview that could exhaust your browser tab.
- The format is read from the file’s own bytes, not its name. A PNG renamed photo.jpg is reported as PNG, and the disagreement is called out on the result.
- Only JPEG, PNG and WebP are accepted. Anything else is rejected before decoding rather than guessed at.
- A header too short to read is not a rejection: the file is still decoded, and the pixel limits are then applied to the real dimensions the decoder reports.
What the inspector reads
Three different sources are behind these numbers. File name and file size come from metadata your browser already has, available before any decoding starts. The format is read from the first bytes of the file, which is the only place the truth actually lives. Width, height and aspect ratio come from the image header, and the preview confirms the picture really decodes.
Sizes use 1 KB = 1024 bytes and 1 MB = 1024 KB. When an application form says 200 KB it normally means the same thing, but leave some headroom rather than landing exactly on the line if a submission still refuses the file.
A file can carry a valid-looking extension and still not be that format. That is one of the commonest reasons a portal rejects an upload, so the inspector reports the format it detected and names the disagreement with the extension instead of quietly picking one.
Aspect ratio, explained
Ratios are reduced to whole numbers while both sides stay under 30, which is where standard camera and screen formats live. A 4000 × 2667 photo reads as 3:2.
An odd size such as 4001 × 2667 is shown as a decimal ratio instead of being rounded to a tidy standard, because a screenshot that has been cropped by one pixel is not a 3:2 image.