Image Resizer & Converter
Resize, compress, and convert images — in your browser, nothing uploaded.
Drop images here, or
Up to 100 at once — nothing is uploaded.
About Image Resizer
An image resizer changes an image's dimensions to an exact pixel width and height, and can compress or convert its format. Load an image, type the new width and height (the aspect ratio stays locked unless you unlock it), and export as PNG, JPEG, or WebP with a quality slider. Everything is processed in your browser, so your images are never uploaded.
Downscaling is safe, upscaling is not
Making an image smaller throws away information, and the result looks fine because every output pixel is computed from several real input pixels. Making it larger has to invent information that was never captured. Interpolation can smooth the gaps, but it cannot recover detail — enlarging a 400px image to 1200px gives you a soft, mushy 1200px image, not a sharper one.
The practical rule is to always start from the largest original you have and size down. If you only have a small file and need it bigger, the honest options are to re-shoot or re-export from the source, or accept the softness. Doubling dimensions is usually the limit before the loss becomes obvious.
Aspect ratio and why images look squashed
Aspect ratio is width divided by height. Changing one dimension without the other stretches the picture, which is instantly visible on faces and circles. Locking the ratio means typing a width and letting the height follow, which is what you want almost always.
When an image genuinely has to fit a different shape — a square avatar from a landscape photo — the answer is cropping, not stretching. Decide what to cut rather than distorting everything. This is also why specifying both dimensions of a target box and forcing an image into it produces the squashed thumbnails you see on badly built sites.
Choosing a format
JPEG is for photographs. It is lossy, discarding detail the eye is least likely to miss, and produces small files for complex continuous-tone images. It handles sharp edges and flat colour badly, which is why text and logos saved as JPEG develop fuzzy halos, and it has no transparency.
PNG is lossless and supports transparency, making it right for logos, icons, screenshots, and anything with crisp edges or large flat areas. It is a poor choice for photographs, where it can be several times the size of an equivalent JPEG. WebP does both jobs — lossy or lossless, with transparency — and is typically 25–35% smaller than the equivalent JPEG or PNG, with support in every current browser.
Getting the file size down
Dimensions dominate file size, because pixel count grows with the square. Halving the width and height quarters the pixels and cuts the file far more than any quality setting will. Before reaching for the quality slider, ask how large the image is actually displayed — serving a 4000px photo into a 600px slot wastes most of the bytes.
For JPEG and WebP, quality around 75–85 is the usual sweet spot; below about 70 artefacts start showing around edges, and above 90 the file grows quickly for differences almost nobody sees. Re-encoding a lossy image repeatedly compounds the damage, so make edits from the original rather than from an already-compressed export.
Frequently asked questions
- How do I resize an image to exact pixel dimensions?
- Load the image, then type the width and height you want in pixels. The output updates instantly, and you can see the new file size before downloading.
- Does it keep the aspect ratio?
- Yes, by default — change the width and the height follows automatically so the image isn't stretched. Click the lock to unlock it if you need a different ratio.
- Are my images uploaded to a server?
- No. Resizing, compression, and conversion all happen locally in your browser — the image never leaves your device.
- Which format should I export — PNG, JPEG, or WebP?
- WebP gives the smallest files at good quality; JPEG suits photos; PNG preserves transparency and sharp edges. For JPEG and WebP, the quality slider trades size against clarity.
- Will resizing reduce quality?
- Shrinking is generally clean; enlarging past the original size softens detail. Adjust the quality setting to balance file size and clarity.