image tool
Blur image online
Pick a blur radius and the whole photo softens, or switch to boxes and drag over the parts to soften, such as a face in the background. The blur is Gaussian, measured in pixels of the full image, so the download matches the preview.
Loading the tool…
- Runs on your device, nothing is uploaded
- Free, no sign in
- No watermark, no file limit
How it works
- 1
Drop the photo
The whole image is blurred at a 12 pixel radius to start, so you can see the effect at once.
- 2
Choose whole image or boxes
Only boxes I draw switches to drawing. Drag on the picture to add a box, drag a box to move it, and add as many as you need.
- 3
Set the radius
Slide the blur radius until the detail is gone. On a face in a crowd that is usually 20 pixels or more on a phone photo.
- 4
Check and download
Show original flips back to compare. Download saves the full-size result as PNG or JPG. Nothing is uploaded and nothing is stored, ever.
Whole image or just a part
Blurring everything is for a background: a soft photo behind a headline, a slide backdrop that must not compete with the words, or a placeholder that hints at a picture without showing it. Blurring a part is for hiding one thing in an otherwise useful photo, such as a stranger's face in an event shot or a whiteboard in an office picture. Draw one box per thing to hide. Each box is blurred from the same softened copy of the photo, so neighbouring boxes match and the edges of the box stay crisp against the sharp picture around it.
How big a radius to use
The radius is the standard deviation of the Gaussian, the same number CSS uses for its blur filter. Detail smaller than about twice the radius disappears. A face that is 80 pixels across in the full-size photo is unrecognisable at around 15 to 20; a whole background behind text usually needs 8 to 12 to look soft without looking smeared. Because the radius is measured in full-size pixels, the same setting looks stronger on a small photo than on a 12 megapixel one, so judge it on the preview rather than by the number.
Clean edges at the border of the photo
A plain canvas blur treats the area outside the picture as transparent, so a blurred photo fades to a see-through rim at its edges. The tool repeats the edge pixels outward before it blurs, then trims back to the original size, so the border of the result stays solid and the colour runs right to the edge.
Limits worth knowing
Blur is not redaction. Blurring smooths detail but keeps a trace of it, and researchers have shown that blurred or pixelated faces and numbers can often be matched or reversed when the set of possible answers is small, such as the digits on a number plate. For text, use the pixelate tool with blocks of 16 pixels or more, or a solid box, and never rely on a light blur for anything sensitive. The tool needs canvas filters; browsers without them get a plain message. Images over 8,192 pixels on the long side are refused rather than crashing the tab.
Before a photo goes on a form
A classic form can show images as design blocks, each with one of 10 border styles, and anyone who can open the form sees them. If a photo of a venue, a team or a past event has people in it who did not agree to appear, blur them here first and upload the blurred copy.
Limits
- Blur is not redaction. A strong blur can still be partly reversed on text, so use pixelate with large blocks, or cover it completely, for names, plates and documents.
- The radius is the standard deviation of the Gaussian, from 1 to 80 pixels of the full-size image.
- Boxes are rectangles. There is no brush and no automatic face finder.
- The tool needs canvas filters, which arrived in Safari 18; an older Safari is told so instead of getting a broken page.
- Images larger than 8,192 pixels on the long side are refused with a message.
What it does not do
- It does not detect faces, plates or text for you. You draw every box.
- It does not blur the background behind a subject the way a portrait mode does; it blurs rectangles or everything.
- It does not keep the photo's EXIF data.
Questions people ask
Can a blurred face or number be unblurred?
Sometimes. A blur throws away fine detail but not all of it, and when the possible answers are few, such as the digits on a plate or a face from a known group, the blurred version can be matched by trying candidates. Use a large radius for faces, and for text use pixelation with big blocks or cover it with a solid box.
How do I blur only the background behind a person?
This tool works in rectangles, so it cannot follow the outline of a person. For a rough result, switch to boxes and draw several around the subject. For a true portrait style blur you need a cut-out of the person: remove the background in another tool, blur this original, then layer the two in an editor.
Why do the edges of my box look sharp?
Each box is filled with the blurred photo and stops at its border, so the line between blurred and sharp is crisp. That is deliberate when hiding something, because a feathered edge lets the hidden detail fade back in. If you want a softer join, draw the box a little larger than the thing you are hiding.
Does the blur change the size of the image?
No. The result has the same width and height as the original, whether you blur all of it or only some boxes. The edges are padded before blurring and trimmed afterwards, so nothing is cropped and no transparent rim appears. The readout under the preview shows the pixel size the download will have.
Can I move or delete a box after drawing it?
Yes. Drag a box to move it. Click a box to select it, then press Delete to remove it, or use the arrow keys to nudge it and Shift with an arrow to resize it. Remove all boxes clears them in one go, and Add a box drops a new one in the middle for keyboard users.
Blur a photo before it goes on a form page
Take what you made here into forms.
Create a form with OneCraftMore tools like this
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- Image compressorCompress to WebP or JPEG and compare the result against the original under a divider you drag. Or ask for a size in KB. Nothing is uploaded.
Background reading: the question page on this.
Written and checked by the OneCraft team. Last checked .