Transparency Checker
Check whether an image really has a transparent background — exact alpha statistics, a switchable preview background, and flatten or trim exports.
Drag & drop an image here, or click to browse
No uploads. Your files stay on your device.
- File
- Dimensions
- Total pixels
- Fully transparent
- Semi-transparent
- Fully opaque
- Lowest alpha
- Visible content
How it works
Drop a PNG, WebP, GIF or any other image and the tool reads every pixel's alpha value with the Canvas API, right inside your browser — the file is never uploaded. You instantly see how many pixels are fully transparent, how many are semi-transparent (soft edges and shadows) and how many are fully opaque, plus the bounding box of the visible content.
A transparent background is invisible against a white page, so switch the preview between a checkerboard, white, black, magenta or any custom colour to spot stray halos and off-white fringes. Use Download flattened PNG to bake the image onto the chosen colour, or Download trimmed PNG to crop away the empty transparent margin. JPEG files have no alpha channel at all, so they always report as fully opaque.
Frequently asked questions
How do I know if my PNG has a transparent background?
Drop the file in and the tool reads every pixel's alpha value instantly. If the whole outer edge is fully transparent it reports "This image has a transparent background", and you get the exact numbers: how many pixels are fully transparent, semi-transparent and fully opaque. Switch the preview to black or magenta to see the cut-out against a colour that a white page would hide.
Why does my image look transparent but export with a white background?
Many editors and converters flatten transparency onto white when saving, especially to JPEG. This checker will then report 0 transparent pixels and 100% fully opaque, which means the "transparency" you see in your editor was never written to the file. JPEG has no alpha channel at all, so re-save as PNG or WebP to keep it.
What are semi-transparent pixels and why do they matter?
Semi-transparent pixels have an alpha between 1 and 254 — they are the soft anti-aliased edges, shadows and glows that make a cut-out blend smoothly. Formats and workflows that only support 1-bit transparency (like GIF, or some icon pipelines) will turn those pixels into hard jagged edges, so a high semi-transparent count is a warning sign before you convert.