What is a Gaussian blur?
A Gaussian blur replaces each pixel with a weighted average of its neighbors, with the closest pixels counting most. The weights follow a bell curve, which is why the result looks smooth, like a lens out of focus, rather than smeared or blocky. It's the default blur in Photoshop, Figma, Canva and CSS for that reason.
The radius controls how far the averaging reaches. Small values soften detail; large values melt shapes into soft areas of color.
The result is saved as a JPG, so any transparent areas in a PNG are not preserved.
| Radius | Effect | Good for |
|---|---|---|
| 1–3 px | Gentle softening | Smoothing noise, a dreamy look |
| 4–8 px | Clearly out of focus | Backgrounds behind text |
| 9–14 px | Shapes still visible, no detail | Teasers, wallpapers |
| 15–20 px | Soft wash of color | Abstract backgrounds, gradients |
Blur an image for a background
To use a photo behind text, upload it, set a radius around 6–10 px and download. Big images need more blur than small ones for the same look, so resize first if your photo is very large. Then add your headline with the Image Text Overlay tool or in your design app.
This tool blurs the whole image. For a portrait-mode look, with a sharp subject on a blurred background, blur a copy of the photo here, cut the subject out of the original with the Background Remover, and layer the cutout on top.
Blur also hides the flaws of a low-quality background photo. A small or slightly noisy image that would look rough at full size often works perfectly once it's blurred, because there's no fine detail left for the eye to judge. That makes blurred photos a handy fallback when you need a large background and only have a small picture.
Is blur safe for hiding private information?
A heavy blur hides faces and scenery well. For text such as passwords, account numbers or addresses, it's safer to cover the area with a solid block, because a light blur on large text can sometimes still be read. When privacy really matters, crop the detail out entirely with the Image Cropper.
