Guide · 2 min read
How to resize an image without losing quality
What resizing really means, why shrinking is safe and enlarging is not, and how to get a photo to exact dimensions without stretching it.
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Resizing an image means changing how many pixels it has. Making it smaller is safe and almost never noticeable; making it bigger adds no detail, it only invents some. Understanding that difference avoids most problems.
Shrinking: what you lose, you were never going to see
A phone photo is around 4,000 pixels wide. Your screen is probably less than half that. When you shrink the photo to 2,000 or 1,200 pixels, the pixels that go are detail your screen was already throwing away to display it.
For the result to look sharp, the software has to compute each new pixel well from the originals. Resize image uses the browser’s own high-quality scaling, the same it uses to display large photos.
Enlarging: the browser makes up the pixels
If you enlarge an image from 400 pixels to 1,600, every original pixel becomes sixteen. The software fills them in by averaging neighbours, and the result is a bigger but blurry image. That is why the tool never goes beyond the original size: we would rather not hand you something that looks like an improvement and is not.
Three ways to set the size
- By percentage. At 50%, width and height are halved, and the file usually ends up a quarter of the size.
- By width or by height. Enter just one and the other is worked out to keep the proportions. This is the most common case: “make it 1,200 pixels wide”.
- By width and height. The image is fitted inside those dimensions without distortion. If the shape does not match, there will be space left on one side.
If you are asked for exact dimensions in a different shape
A form asking for 600 × 600 pixels expects a square image. If your photo is rectangular, the tool fits it inside without stretching, so it will come out narrower or shorter. To fill the whole square, crop it first in your phone’s or computer’s editor, then resize.
Useful sizes
- To send by email or messaging: 1,600 to 2,000 pixels on the long side.
- For a website or online shop: 1,200 to 1,600 pixels wide.
- Profile picture: a square of 800 to 1,080 pixels.
And if it also needs to be small
Resizing already cuts the file size a lot. If you have a specific limit in KB, run the image through Compress image afterwards and type the limit. Both tools work in your browser, and neither uploads your photos.