Resolution Checker
Check an image's real dimensions, megapixels, aspect ratio, encoding and colour information.
Convert with this tool
or choose a file from your device — it is processed in this tab and never uploaded
Accepted: JPEG, PNG, WebP, GIF, AVIF, BMP
Files stay on your device. There is no upload, no queue and no watermark, so a conversion works even with the network switched off after the page has loaded.
Supported formats & processing
| Accepted input | JPEG, PNG, WebP, GIF, AVIF, BMP |
|---|---|
| Produced output | An inspection report with a downloadable JSON file |
| Processing | Web Audio API + canvas + native JavaScript encoders |
| Upload required | No — the file is read locally and never transmitted |
How to use this tool
- Add the imageThe dimensions are read from the decoded bitmap.
- Check the megapixel countUseful for judging whether the file is large enough for print.
- Read the encoding rowBaseline versus progressive JPEG matters for how the image loads.
- Check the colour componentsThree components means RGB or YCbCr; four can mean CMYK or RGBA.
- Note the EXIF rowIf metadata is present, the image may carry camera and location information.
About this tool
Image files carry two kinds of information: the pixel data itself, which determines the resolution, and the header, which records how that data was encoded. Both matter — a 4000 × 3000 photo at 60 percent JPEG quality will look worse than a 2000 × 1500 one at 92 percent when both are displayed at the same size.
This checker reads the pixel dimensions from the decoded image and the encoding details from the file header: for JPEG the SOF marker gives the encoding mode and colour component count; for PNG the IHDR chunk gives the bit depth, colour type and interlacing; for WebP the chunk identifier reveals whether it is lossy VP8, lossless VP8L or extended VP8X.
Features
- Pixel dimensions and megapixel count from the decoded image
- JPEG encoding mode and colour component count from the SOF marker
- PNG bit depth, colour type and interlacing from the IHDR chunk
- WebP variant detection — VP8, VP8L or VP8X
- EXIF presence check for privacy awareness
- Downloadable JSON report
Frequently asked questions
How many megapixels do I need for print?
At 300 dots per inch, an A4 print needs about 8.7 megapixels and a 10 × 8 inch print needs about 7.2. For screen use, anything above 2 megapixels is usually more than enough.
What is the difference between baseline and progressive JPEG?
Progressive JPEGs store the image in several passes of increasing detail, so a low-quality version appears quickly and sharpens as it loads. Baseline stores it top to bottom in one pass. Progressive is generally better for the web.
Why does my JPEG report four colour components?
Four components usually means CMYK, which is a print colour space. Browsers decode CMYK JPEGs but often render the colours incorrectly, so converting to RGB is advisable before using them on the web.
Does this tool show where a photo was taken?
It reports whether EXIF metadata is present, which is the signal that GPS coordinates may be embedded. It does not extract the coordinates themselves. Re-encoding the image through any of the conversion tools strips the metadata entirely.