Image Size Checker

Upload forms, print shops, app stores and marketplaces all have rules: a minimum size, an exact ratio, a file-size limit, 300 dpi, no transparency, no animation. This checker reads each image's own bytes and lists everything that matters in one place: pixel dimensions, aspect ratio, megapixels, file size, the real format behind the extension, DPI, bit depth and colour type, JPEG subsampling, transparency, animation frames, colour profile and EXIF orientation. You can check a whole batch at once, and nothing is uploaded.

How to use this tool

1. Drop one or more images (JPG, PNG, WebP, GIF, AVIF, HEIC, TIFF, BMP, ICO, SVG or PSD).
2. Optionally change the DPI used for the print-size column (300 by default).
3. Read the summary and the detailed table for each file; for images with transparency, download the transparency map.

Formula

aspect ratio = width ÷ gcd(width, height) : height ÷ gcd(width, height); megapixels = width × height ÷ 1,000,000; print size = pixels ÷ DPI (inches) × 2.54 (cm)

Dimensions and details come from the file headers (PNG IHDR and chunks, JPEG SOF and APP markers, GIF blocks, WebP chunks, TIFF tags, HEIC/AVIF ispe, clap and irot boxes), so they are exact even for formats the browser cannot display. Transparency is measured by decoding the pixels and counting alpha values. When a ratio does not reduce to small numbers, the nearest common ratio within 1% is shown, e.g. 1366:768 ≈ 16:9.

Example

A 4032 × 3024 iPhone photo: gcd = 1008, so the ratio is 4:3 (1.333), and it has 4032 × 3024 ÷ 10⁶ = 12.19 MP. At 300 dpi it prints at 4032 ÷ 300 = 13.44 in = 34.14 × 25.60 cm. A 1366 × 768 screenshot reduces to 683:384 and is shown as ≈ 16:9.