Free web tool
Inspect transparent, semi-transparent, and opaque pixel ratios and the visible-content bounds.
Measure how much of a PNG, WebP, or other image is fully transparent, semi-transparent, or opaque. It is useful when a background should be transparent, or when you want to know how tightly visible content fits inside the canvas.
Alpha is the per-pixel transparency value. This tool classifies 0 as fully transparent, 1–254 as semi-transparent, and 255 as opaque.
That makes it possible to spot soft semi-transparent edges instead of only asking whether transparency exists at all.
The tool finds the minimum and maximum X/Y coordinates where Alpha is greater than zero. A file with a large transparent margin will therefore show the actual region occupied by visible pixels.
It does not crop the image. Use Image cropper when you want to remove the margin.
JPEG normally has no Alpha channel, so browsers decode it as opaque pixels. Use PNG or another transparency-capable format when transparency must survive.
For format trade-offs, see JPEG vs PNG vs WebP vs AVIF.
An image can store RGB values under pixels whose Alpha is zero. You cannot see those colors until another operation removes or changes the transparency.
This checker measures Alpha. It does not judge the hidden RGB values under transparent pixels.