Trim Transparent Images

Trimming finds the smallest rectangle that holds every pixel that isn’t fully transparent, and cuts away the empty rows and columns around it, like an automatic crop. A 400 × 300 PNG with a logo in the middle might come out 160 × 140. Nothing inside the rectangle changes: solid pixels are copied exactly, and every pixel keeps its transparency.

It’s useful for:

• Logos exported on a large artboard, whose hidden margin makes them look small or off-centre on a website or in an email signature.
• Icons and favicons, so the artwork fills its box. Empty edges make a favicon look smaller than it needs to.
• Product cut-outs, so each product fills its space the same way on a shop page.
• Sprites and game art, which then pack more tightly into a sprite sheet.

Trimming gives each image its own size, though. Icons drawn on matching canvases, or the frames of an animation, stop lining up if you trim them one by one, so keep the originals for those.

Every pixel has an opacity (alpha) from 0, invisible, to 255, solid. Tolerance (0 to 255) sets how faint a pixel can be and still be cut: anything at or below it counts as empty. At the default of 0, only fully transparent pixels go, so soft edges, drop shadows and glows are kept.

That also means a speck you can’t see can stop the trim. A 100 × 100 square with one pixel at opacity 1 near the corner of a 400 × 300 image trims to 296 × 196 at Tolerance 0, and to 100 × 100 at 1. If an image hardly shrinks, raise the Tolerance a little and press Rerun with new settings.

Higher values cut fainter artwork too: a shadow at opacity 10 is kept at 9 and cut at 10. Tolerance only moves the edges; faint pixels inside them are left alone. If no pixel is more opaque than the Tolerance, nothing would be left, so the file is listed as an error instead.

Padding (0 to 50 px) puts back a transparent margin on every side, so a logo doesn’t touch the edge of whatever it sits in. With 10 px, the 160 × 140 logo above becomes 180 × 160.

The margin comes from the space the image already had, so padding never makes it bigger than the original, and a side where the artwork touches the edge gets none: 50 × 100 artwork against the left edge becomes 60 × 120 with 10 px, not 70 × 120.

Only transparency is trimmed. A white or coloured background is made of solid pixels, so a PNG on white comes out the same size it went in. To cut off a white border, use Crop. Image Toolkit doesn’t remove backgrounds, so a logo on white needs an editor with background removal first.

The trimmer takes the formats that can be transparent: PNG, WebP, GIF and AVIF. JPGs can’t store transparency, so they and any other files you add are listed as skipped. An animated GIF or WebP is trimmed as a still image of its first frame.

Trimmed images are always saved as PNG, which is lossless and keeps the transparency exactly. A PNG keeps its name, other formats get .png instead (logo.webp becomes logo.png, as each result shows), and ticking Add "_trimmed" suffix gives logo_trimmed.png. Download ZIP saves a batch as trimmed_images.zip, numbering any files that share a name. Your settings are remembered on this device.

A trimmed file isn’t always smaller. Empty areas already compress to almost nothing, and browsers save PNGs with less effort than dedicated optimisers, so it can come out slightly bigger; a WebP, AVIF or GIF usually comes out bigger as a PNG, as those formats pack pixels more tightly. The tool says so when it happens. For a website, WebP keeps the transparency and usually makes a smaller file: pass the results to the Image Converter with Send to....

Trimming happens in your browser, on your own phone or computer, so your images are never uploaded. That matters for unreleased logos and client artwork.

To check, open your browser’s developer tools, watch the Network tab and trim a few images: no request carries them. Apart from the page’s own code, the only requests are anonymous usage counts, described in our privacy policy. After your first visit, the trimmer works offline too.