What resizing changes, and what it doesn't
Resizing changes the number of pixels in a picture. A 4000 × 3000 phone photo has 12 million pixels; resized to 1600 × 1200 it has under 2 million. On a normal screen it looks the same, but it opens faster and weighs a fraction of the original.
Resizing does not change what is in the frame. If you need a different shape — a square from a landscape photo, say — that's cropping. This tool scales the whole picture. For exact shapes, use one of the size presets below or Crop Image.
Three ways to set the size
- Width or height with "lock ratio" on. Type one number and the other follows. This is the safe default: nothing gets stretched.
- Scale in percent. 50% halves both sides; the field accepts 1 to 400%.
- Both numbers with the lock off. The picture is stretched or squeezed to exactly what you type. Only do this when the change is tiny — a face squeezed by 10% already looks wrong.
Pixels and file size
File size roughly follows the pixel count. Halving the width and height leaves a quarter of the pixels, so a 3 MB photo usually comes out somewhere around 0.6–1 MB. It's never exact: detail, noise and the format matter as much as the dimensions.
If a form asks for a limit in KB rather than pixels, resizing alone is guesswork. Use Compress Image or a fixed target such as compress to 200 KB, which adjust quality until the file fits.
Which size to pick
| Where the image goes | Longest side, typically |
|---|---|
| Email attachment, messenger | 1280–1600 px |
| Blog post or web page | 1200–2000 px |
| Full-screen slide or wallpaper | 1920 px (Full HD) or 3840 px (4K) |
| Profile picture | 400–1024 px |
| A4 print at 300 DPI | 3508 px (A4) |
For social networks, the exact presets are easier: Instagram post, Instagram story, YouTube thumbnail. Unlike the free-size tool, they also crop or pad the image to the required shape.
Making images bigger
You can enlarge up to 400%, but enlarging doesn't add detail. The browser interpolates between the pixels that exist, so edges get softer. Up to about 1.5× this is usually fine on screen; at 2× and beyond, text and fine textures look blurred. If you need a large image, start from the largest original you have rather than a copy downloaded from a chat.
Format and quality of the result
The result keeps the format of your file: JPG stays JPG, PNG stays PNG with its transparency, and WebP stays WebP where the browser can encode it (otherwise it becomes JPG, or PNG if it has transparent areas). GIF and SVG come out as PNG, and an animated GIF keeps only its first frame. JPG and WebP are saved at 92% quality, which is visually indistinguishable from the original for photos. To switch formats deliberately, use the image converter.
Saving a new file also drops EXIF metadata such as the camera model and GPS location. To see what a file carries, open it in the EXIF viewer.
Size limit
The result can be at most about 16.7 megapixels — for example 4096 × 4096 or 5000 × 3350. That is the canvas limit of Safari on iPhone, and the tool applies it on every device so results don't differ between phone and computer. If you type more, the size is reduced proportionally and a note shows the dimensions you actually got.
Everything runs in your browser: the image is never uploaded, so resizing a 20 MB photo takes as long as your device needs, not your connection.