An image dimensions checker reports the pixel width and height of a decoded image, plus the file size and the detected type. This page does that locally. You choose a JPEG, PNG, or WebP. The script sniffs magic bytes, decodes the bitmap, and prints width, height, megapixels, bytes, detected MIME type, and a sanitized filename. The filename is written with textContent. It is never injected as HTML.
The type is not taken from the extension. A JPEG named shot.png is still image/jpeg. SVG, GIF, and HEIC are refused. This page does not parse EXIF. If the browser applies orientation during decode, the reported size is the oriented bitmap. If you needed a new size after you read these numbers, use the Image Resizer.
Empty selection, unsupported type, oversized file, and decode failure are errors. The 8 MB, 8,000 px, and 16 megapixel caps still apply so a huge file is refused instead of locking the tab. Nothing is uploaded. Nothing is stored.
A 3840 × 2160 photo reports 8.29 megapixels. A 1280 × 720 screenshot reports 0.92 megapixels. A 400 byte text file renamed to .jpg is unsupported. A 12 MB camera file is oversized. Those are expected errors, not crashes.
Use the numbers to decide whether to resize, crop, or leave the file alone. Do not treat megapixels as print quality. Print quality depends on inches and a printer, which this page does not compute. Do not treat the sanitized filename as proof of origin. It is only the local name after unsafe characters are stripped.
A form that says “maximum 2000 px on the long edge” is a common reason to open this page. Read the long edge. If it is 4000, go to the resizer and set 2000 with aspect locked. If it is already 1200, leave it. This checker will not resize for you. That split keeps the page honest and keeps the resizer as the place where encoding happens.
The preview is a scaled canvas so you can confirm you chose the right file. It is not a zoom studio. Dimensions come from the decoded bitmap, not from the preview element. If decode fails, you get an error instead of 0 × 0. If the file is a JPEG with a thumbnail in EXIF, this page still reports the main bitmap the browser decoded, not the thumbnail.
Privacy and security match the cluster. No upload. No metadata dump. No HTML from the filename. SVG refused. 8 MB cap. If you wanted a full EXIF viewer, that candidate was rejected because reliable IPTC and XMP parsing needs a large library this cluster will not add.
Check can be pressed again on the same file. That re-reads the bytes. It does not store a previous result. If you change the file on disk and select it again, you get the new size. The page will not watch the folder for you. On a 390px screen the result rows stack the label and the value so a long sanitized name can wrap instead of overflowing the card.
Dimensions come from the decoded bitmap. The type is sniffed from file bytes, not the extension. SVG, GIF, and HEIC are not accepted.
No. Type is sniffed from the first bytes.
No. This page reports decoded pixels and file size only.
No. The check stays in this browser.
Use the Image Resizer after you read the current dimensions.
