Wrap a smooth stroke around the shape of any transparent PNG, not just its rectangle. Make a white sticker border, a bold comic outline or a soft glow, choose the width and color, add a second outer border, and download a transparent PNG.
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Rendering…
Sample cutout
Position
Pixels more opaque than this count as the object. Raise it to ignore faint halos or shadows.
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How to use the Add Outline to PNG
Add a transparent PNG by dropping it, pasting it or pressing Choose PNG. A sample cutout is loaded so you can try the settings first.
Pick a preset such as Sticker, White border or Neon glow, or set the position, width and color yourself.
Adjust softness and corners, and turn the second outline on or off.
Check the preview on the checkerboard, white, dark or blue background.
Download PNG, copy it to the clipboard, or download all images as a ZIP.
How the outline is calculated
The tool first decides which pixels belong to the object: every pixel whose opacity is above the edge threshold (50% by default). It then runs an exact Euclidean distance transform, which gives every pixel its straight-line distance to the nearest object pixel. All pixels within the chosen width become part of the outline, so the stroke has the same thickness everywhere and its outer corners are perfectly round, exactly like expanding a selection in a photo editor. With Sharp corners the chessboard distance is used instead, which keeps square corners square.
The edge of the outline is anti-aliased over one pixel, and the softness setting widens that ramp. Layers are then stacked from back to front: the second outline, the main outline, and finally your original image on top, so semi-transparent edges of the object blend into the outline instead of showing a gap.
Outline width guide
Image size (longest side)
Subtle outline
Sticker border
Bold comic outline
256 px (emoji, chat sticker)
2 px
6 px
8 px
512 px
3 px
10–12 px
14 px
1000 px
5 px
18–24 px
28 px
2000 px (print)
8 px
36–48 px
55 px
A good rule of thumb: a sticker border is roughly 2–2.5% of the image's longest side.
Tips
For printed die-cut stickers, keep the white border at least 1.5 mm wide at the printed size so the cutting blade has room.
Thin, wispy parts such as hair or grass create a bumpy line. Raise the edge threshold or add 2–4 px of softness.
A dark thin second outline around a white border makes the sticker stand out on white backgrounds.
Use an inside stroke when the image must keep its exact size, for example a game sprite.
Frequently asked questions
How do I add an outline to a PNG image?
Open the PNG in the tool above. It finds the edge of the visible object using the transparency of each pixel and draws a stroke of the chosen width and color around that shape. Pick a preset or set the width, color and softness, then download the outlined PNG.
Why does the outline only go around the rectangle of my image?
The image has no transparent background, so the whole rectangle counts as the object. Remove the background first, for example with the Background Remover, and then add the outline here.
What is the difference between outside, center and inside strokes?
An outside stroke is drawn around the object and makes it look bigger, which is what stickers use. A center stroke straddles the edge, half outside and half inside. An inside stroke stays within the object, so the image size and silhouette do not change.
How do I make a sticker-style white border?
Choose the Sticker preset: a white outline of about 12 px with a thin dark outer border. Use round corners so the border follows curves smoothly, and keep the canvas expanding so nothing is cut off.
What does the softness slider do?
Softness feathers the outer edge of the outline over the given number of pixels. Small values smooth jagged edges, larger values with a bright color create a glow effect.
Why is the outline bumpy around hair or fur?
Fine, semi-transparent details create many small edges. Raise the edge threshold so only the solid parts count as the object, or add a little softness for a smoother line.
Is my image uploaded?
No. The outline is calculated with JavaScript in your browser, so your images never leave your device.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.