# Blur Image Online

> A free online tool that blurs, pixelates (mosaic) or covers with a solid block a whole picture or up to 10 boxes you draw, and saves it as PNG, JPEG, WebP or GIF; only the solid block is a safe way to hide information.

Blur Image with this free online tool, one picture at a time. Blur the whole picture, or draw boxes around the parts you want to blur, cover with a mosaic or hide with a solid block. A blur is not a safe way to hide private details; only the solid block is. Your original file stays unchanged.

## Key facts

- Input: one picture up to 5 MB in the free tool and 10 MB when signed in, and up to 16 MP (4096 x 4096); animated GIF and WebP are blurred frame by frame within the animation limits.
- Settings: the mode (blur, mosaic or solid block), the whole picture or drawn boxes, the blur strength (sigma, default 5), the mosaic block size (2 to 200 px, default 16) or the block color, save as the same type, PNG, JPEG, WebP or GIF, and quality for JPEG and WebP.
- A light blur can be undone by software and small mosaic blocks can be guessed, so a face, a number or an address should be covered with the solid block mode; outside the drawn boxes no pixel changes.
- The upload is deleted when the job ends and the result after 10 minutes; signed-in users pay 1 credit per file plus 1 credit for each started 5 MB of result beyond the first 5 MB and, for an animation, 1 credit for each started 10 MP of frames beyond the first 10 MP.
- Free without an account: up to 10 conversions per minute and 50 per day per visitor, no watermark. Signed in, each render costs 1 credit (100 free credits every month).
- Files are deleted automatically: 10 minutes after conversion without an account, 1 day with a free account.
- Developers can run the same job with POST https://api.aiipworld.com/v1/image-jobs?op=image_edit (the image as the request body, settings in the query string) and an API key (see the API docs page).

## How it works

1. Upload one picture in a supported format: PNG, JPG, WebP, AVIF, GIF, BMP or TIFF.
2. Choose a "Mode" from Blur, Mosaic (pixelate) or Solid block.
3. Under "Apply to", keep "The whole picture" or choose "Chosen areas" and drag boxes on the preview.
4. Set the blur strength (sigma, default 5, from 0.3 to 50), the mosaic block size (default 16) or the block color.
5. Choose "Save as". The default, Same as the original, keeps the file type of your picture.
6. If you save as JPEG or WebP, adjust the Quality slider. The default is 90.
7. Click "Blur image" and download the result from the result panel.

## How to Blur Image Files Online

You can blur photo files, or blur picture files of any other supported type. Upload your picture, set a strength, and click "Blur image". By default the tool blurs the entire picture in one pass, or only the boxes you draw, and shows the result in the result panel. You can then download the blurred copy.

Use a supported format and make sure you have the right to use the picture. The file is checked by its content, not its name, so a text file renamed to .png will be refused.

- Start with the default strength of 5 and adjust from there.
- Try a lower value first if you only want to soften the picture a little.

## Blur Image Strength: What the Numbers Do

The strength is a Gaussian blur, and the number is the standard deviation in pixels. The same number looks stronger on a small picture than on a large one, so compare results on your own picture. Use a larger number for a stronger image blur.

For a photo about 4000 px wide, values from 0.3 to 1 soften a little, 1 to 3 is light, and 3 to 8 gives a medium soft-focus look with a blurred background. From 8 to 20 fine detail is gone, and 20 to 50 leaves only blocks of color. Values below 0.3 or above 50 are refused.

## Blur Part of a Picture: Draw Boxes

Choose "Chosen areas" under "Apply to", then drag on the preview to draw a box. Drag a box to move it, drag a corner to resize it, or type its Left, Top, Width and Height in pixels of the original. You can draw up to 10 boxes, remove any of them, and boxes may overlap. Pixels outside the boxes are not changed.

In our test of a mosaic in two boxes on an 800 x 560 px PNG, no pixel outside the boxes changed. A box that goes outside the picture is refused, not shrunk.

## Three Modes: Blur, Mosaic, Solid Block

Blur is a Gaussian blur with a strength from 0.3 to 50. Mosaic (pixelate) turns each square block into its average color; the block size goes from 2 to 200 px and the default is 16. Solid block fills the box with one opaque color, black by default.

All three modes work on the whole picture or on chosen boxes, so a blur pic for a soft-focus look and a covered area use the same steps. With one 560 x 70 px box on our 800 x 560 px test illustration (24 KB), a solid block gave 20 KB, a 16 px mosaic 21 KB and a sigma 5 blur 27 KB as PNG.

## Hide Private Information with a Solid Block

A blur is not a safe way to hide a face, a number, a name or an address. Software can sometimes undo a light blur, especially on small text, and a mosaic with small blocks can sometimes be guessed.

To cover an ID number, a card number or a license plate, choose Solid block. It replaces the pixels in the box with one color in the file we return, so nothing is left underneath. If you prefer a mosaic, use big blocks, about a third of the text height or more. Your original file on your device is not changed.

## Choose the File Format

"Same as the original" is the default and keeps the type of your picture. A GIF stays a GIF, BMP and TIFF are saved as PNG, and AVIF is saved as WebP.

PNG keeps every pixel, so it suits sharp graphics. JPEG and WebP are lossy and give smaller files for a photo. Quality from 1 to 100 applies to JPEG and WebP, and the default is 90.

- Choose PNG for illustrations with flat colors.
- Choose JPEG or WebP for photos when file size matters.

## File Size of a Blurred Picture

A blurred picture is not always smaller. In our tests on a generated 800 x 560 px PNG illustration (24 KB), sigma 5 gave 89 KB, sigma 8 gave 118 KB, and sigma 50 gave 291 KB as PNG. Smooth gradients compress worse than flat colors.

Results vary with the picture. Our measurements were made on generated test pictures, not real photos, so test your own file.

## Blurring an Animated GIF or WebP

Animated GIF and WebP files are blurred frame by frame. The frame delays and loop count are kept when the output is GIF or WebP and the animation checkbox is on.

In our test, a 24 frame 320 x 240 px GIF of 88 KB blurred with sigma 3 became a 24 frame GIF of 166 KB. With PNG or JPEG output, or with the checkbox off, only the first frame is used.

## Limits: Size and Pixels

Each picture can be up to 5 MB without an account and up to 10 MB when signed in. The pixel limit is 16 MP (4096 x 4096) per picture, and it is checked before the picture is opened.

The result can be up to 40 MP, and WebP results can be up to 16,383 px on a side. A result over these limits is refused before any work is done, so it is never silently shrunk.

## What to Check in the Result

The result panel shows the picture, its size, the mode, the strength or block size used, how many boxes were applied, and your credits. Check that the strength looks right for your purpose before you download.

Check the notes in the panel, since they report what the engine did. The picture size does not change with a blur.

## Blur an Image from Code

Send a POST request to https://api.aiipworld.com/v1/image-jobs?op=image_edit&action=blur with the raw picture bytes as the body, not JSON or multipart. Set the Content-Type to the picture type, such as image/png or image/jpeg, and pass the strength and other settings in the query string.

To change only parts, add regions=x,y,width,height;x,y,width,height (up to 10 boxes, in pixels of the original; add unit=percent for percentages of the picture) and choose mode=blur, mode=pixelate with block, or mode=solid with color. A box outside the picture fails with invalid_input.

Authorize with "Authorization: Bearer `<API key>`" or "x-api-key". The response is 202 with a job_id, and you poll GET /v1/jobs/:id to get a short-lived download_url. The page shows a ready cURL, Node and Python example built from your settings. Errors include 400 invalid_params, 400 unsupported_image, 413 file_too_large, 402 insufficient_credits and 429 rate limited.

## Privacy: What Happens to Your Picture

Your file is sent to our server, and nothing is edited in the browser. The file is used only to make the result, and the working copy is deleted as soon as the job ends, whether it succeeds or fails.

The result is deleted after 10 minutes in the free web tool, and no history is kept. Download links are short-lived, so save your result when it is ready. Camera and location tags are not written to the result.

## Questions

### Can I blur an image for free?

Yes, you can blur an image for free with no signup. Anonymous use needs a quick human check, and you get 30 jobs per day per visitor.

### How do I blur a photo?

Upload the photo, set the blur strength, and click "Blur image". Then download the result from the result panel.

### Can I blur only one part of the picture?

Yes, choose "Chosen areas" and draw up to 10 boxes on the preview. Pixels outside the boxes stay unchanged.

### Is it safe to blur a face or a number?

No, a blur is not a safe way to hide a face or a number. Use the Solid block mode, which replaces the pixels with one color.

### What is the difference between blur, mosaic and a solid block?

A blur softens detail, a mosaic turns each block into one average color, and a solid block covers the area with one color. Only the solid block removes the content for good.

### Which blur strength should I choose?

Start with the default of 5, which gives a medium soft-focus look on a photo about 4000 px wide. Lower values soften a little, and higher values remove more detail.

### Why is the blurred PNG bigger than the original?

A blurred PNG can be bigger because smooth gradients compress worse than flat colors. In our tests, a PNG illustration grew from 24 KB to 89 KB at sigma 5. JPEG or WebP gives smaller files for a photo.

### Can I undo the blur?

Keep your original file, because this tool cannot reverse a blur. Software can sometimes undo a light blur, so do not rely on a blur to hide anything.

### Can I blur an animated GIF?

Yes, every frame is blurred and the animation is kept when the output is GIF or WebP and the animation checkbox is on. With PNG or JPEG output, only the first frame is used.

### Does the picture size change?

No, the picture size does not change when you blur it. Only the look of the pixels changes.

### Can I blur an image in my own code?

Yes, use the image_edit endpoint with action=blur and send the raw picture bytes; add mode and regions to change only parts. The page shows ready cURL, Node and Python examples built from your settings.

## Related

- [Rotate Image Online](https://aiipworld.com/tools/rotate-image/index.md)
- [Flip Image Online](https://aiipworld.com/tools/flip-image/index.md)
- [Convert Image to Black and White](https://aiipworld.com/tools/image-to-black-and-white/index.md)
- [Crop PNG Online](https://aiipworld.com/tools/crop-png/index.md)
- [Add Border to Image](https://aiipworld.com/tools/add-border-to-image/index.md)
- [Round Image Corners](https://aiipworld.com/tools/round-corners-image/index.md)

Page: https://aiipworld.com/tools/blur-image/