Gaussian blur
Soft blur by radius.
This runs in your browser. Nothing is uploaded.
About Gaussian blur
Blurs an image by a radius you set, replacing each pixel with the average of its neighbours in two passes, computed in your browser so the file stays on your device.
Blur gets reached for three unrelated reasons: softening a busy background so the subject reads first, knocking down detail in something you would rather people did not study closely, and turning a photograph into a soft texture for a heading or a card. All three want the same control — one radius, applied evenly across the frame — which is what the single slider here gives you.
The slider sets a radius between 1 and 40 pixels. Each pixel becomes the average of everything within that radius, calculated as two separable passes: horizontal first, then vertical. That makes it a box blur rather than a true Gaussian bell curve, and at the top of the range you can occasionally spot faint square structure around very high-contrast edges. For backgrounds and textures the difference is academic.
Blur is not redaction. A heavy blur over a name or a registration plate is hard to read, but the averaged pixels still carry information about what was underneath, and the smaller the region the more can be inferred from it. If the content genuinely matters, crop it out — that removes the data rather than obscuring it. Worth knowing too: the work happens on a background worker thread, so a 24-megapixel photo at radius 40 will take a few seconds.
How to use Gaussian blur
- 1Drop an image onto the panel, or click it to browse your files.
- 2Set the Strength slider. It is the blur radius in pixels, from 1 to 40.
- 3Click Apply preview to see the blur on the image.
- 4Click Download to save the result as a PNG.
What it won't do
- One radius applied to the whole image — there is no brush, mask or gradient for blurring only part of it.
- A two-pass box approximation, not a true Gaussian kernel.
- Downloads are PNG, so a blurred photo can come out larger than the JPEG you started with.
Common questions
How do I blur an image without uploading it anywhere?
Load the image into this page and move the Strength slider. The blur is calculated by your own browser using a worker thread, and the file is never transmitted. Once the page has loaded you can disconnect from the network entirely and it will keep working, because nothing about the operation needs a server.
Is blurring enough to hide sensitive information in a screenshot?
Not reliably. Blurring averages pixels rather than discarding them, so some of the original signal survives in the result — especially over a small region containing text in a predictable font. For anything that would actually cause harm if read, crop the region away or paint over it with the draw tool.
Why does a high blur strength look slightly blocky?
Because this is a two-pass box blur, not a true Gaussian. A box blur weights every pixel in the radius equally, which can leave faint square edges around bright highlights at large radii. Two passes soften that considerably, and below about radius 20 it is not visible on photographic content.
What blur radius should I use?
It depends entirely on image size, since the radius is in pixels rather than a percentage. On a 1000-pixel-wide image, 3 to 6 gives a gentle softening and 20 makes the subject unrecognisable. On a 6000-pixel photo the same values do far less, so scale up accordingly or resize first.
Related tools
Why this one doesn't upload your file
There is no server to upload to. This page is a static file, and the work happens in your browser using the same graphics and WebAssembly code that renders every other site you visit. Your file is read from disk into memory, processed, and handed back as a download. Once the page has loaded you can disconnect from the network entirely and it keeps working. The longer explanation