Fit Image to Aspect Ratio With Blurred Background

How to use the fit image to aspect ratio with blurred background

1. Choose an image: JPG, PNG, WebP, GIF, BMP or AVIF, up to 25 MB and 40 megapixels.
2. Pick the frame shape (square, 4:5, 9:16, 16:9 and others, or a custom ratio) and the longer side in pixels.
3. Adjust the background blur as a percent of the shorter side, and the brightness of the background.
4. Check the preview and the size line, then choose Create and download as PNG or JPEG.

How the picture is placed

The frame size comes from the ratio and the longer side. A 9:16 frame with a longer side of 1,920 pixels is 1,080 by 1,920. The picture is scaled to fit entirely inside that frame without cropping or stretching, and it is centered. For a 4,000 x 3,000 photo the scale is 0.27, so the picture becomes 1,080 x 810 pixels and sits 555 pixels from the top. Unticking "enlarge a small picture" keeps a small picture at its own size instead of scaling it up.

Behind the picture, a second copy of the photo is scaled to cover the whole frame. Its crop is centered, so in the same example it takes a 1,687.5 x 3,000 pixel window of the original. That copy is blurred and dimmed slightly, then stretched to the frame. The blur is computed with three passes of a box blur that approximate a Gaussian, on a reduced copy so it stays fast.

Where it helps and what to watch

The filled frame is useful when a picture must go in a shape that does not match it, such as a landscape photo in a tall frame. It avoids white bars and avoids cropping people or edges. A low blur gives a sharp echo of the photo, and a high blur gives soft color fields. If the photo is nearly the right shape, the background is barely visible. For plain bars of a color, use the pad image to square tool. To find the dimensions of a ratio, see the aspect ratio calculator, and to change the size of a photo, the image resizer.

Transparent areas of the picture are filled with white first. Everything happens on your device; the saved file has exactly the pixel size shown on the page, up to 4,096 pixels on the longer side.

Assumptions and limits

• The picture is never cropped or stretched in the foreground. Only the blurred background is cropped.
• The output size follows the ratio and the longer side, rounded to whole pixels.
• The blur strength is a percentage of the shorter side of the frame, applied to a reduced copy and scaled back.
• Metadata such as the camera and location is not copied to the saved file.

Formulas reviewed October 10, 2026. See the calculation methodology for how SumPanda rounds, tests and sources its formulas.

Frequently asked questions