Free Image Resizer
Resize, reduce, crop, and compress images online for free directly in your browser with 100% privacy.
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Resize, compress or convert: three different jobs
People use "resize" to mean three separate things, and mixing them up is the usual reason an upload gets rejected. Resizing changes the pixel dimensions. Compressing changes how many bytes those pixels take up. Converting changes the container, for example HEIC to JPG. They interact, but they are not the same control.
A typical phone photo is 4000 × 3000 pixels (12 megapixels) and 3-5 MB as a JPEG. Scale it to 1200 × 900 and you keep about 9% of the pixels. Saved as a JPEG at around 85% quality, that usually lands between 100 and 300 KB depending on how detailed the scene is, and on a normal screen it looks the same. Halving the file size by quality alone would have left you with a 12-megapixel image that is far larger than any screen needs. For web use, reducing dimensions first is almost always the better lever.
Pixels, centimeters, inches and DPI
Pixels are the only unit a screen cares about. Centimeters, millimeters and inches only matter for print, and they mean nothing without a resolution. The relationship is simple: pixels = inches × DPI. A 4 × 6 inch print at 300 DPI needs 1200 × 1800 pixels. A 35 × 45 mm passport photo at 300 DPI works out to roughly 413 × 531 pixels.
In ResizeAny you can type dimensions in px, cm, mm, inch or percent. When you use a physical unit, set the DPI (anything from 10 to 2400). Left on Auto, the tool uses 96 DPI for the conversion, which is the screen default and usually too low for print. For JPEG and PNG output the DPI value is also written into the file, so a program that reads that metadata will report the print size you intended. It does not add detail: a 600 × 400 image labeled 300 DPI is still only 2 × 1.3 inches of real information.
Hitting an exact file size: 20 KB, 50 KB, 100 KB, 200 KB
Government portals, job sites and exam forms often cap uploads at a fixed size. Enter your limit in the target file size field and leave the dimensions on Auto. The tool then searches for the combination that fits: it lowers the encoding quality in steps, and if quality alone cannot reach the target it also scales the image down, stopping at the best result under the limit.
Be realistic about what is possible. A sharp 12-megapixel photo cannot become 20 KB without losing detail; something has to give, and usually it is resolution. If the portal also demands specific dimensions, set those first and the file size second. Transparency is lost when converting to JPG.
Target sizes work with lossy formats (JPG, WebP, AVIF). PNG is lossless, so quality cannot be tuned, and a large PNG may only shrink by being resized or converted to JPG or WebP.
Which format should you export?
| Format | Best for | Watch out for |
|---|---|---|
| JPG | Photos, forms, email. Accepted everywhere. | No transparency; repeated re-saving adds artifacts. |
| PNG | Screenshots, logos, text, transparency. | Large for photos; no quality-based size targeting. |
| WebP | Websites; usually smaller than JPG at similar quality. | Some older apps and forms reject it. |
| AVIF | Smallest files for modern browsers. | Encoding is slower than JPG or WebP, and some older apps cannot open it. Keep a JPG copy when in doubt. |
| HEIC | Input from iPhones (decoded in your browser). | Export is not offered: browsers cannot create HEIC files. Choose JPG, which opens everywhere. |
| BMP | Accepted as input only. | Export to JPG or PNG. |
How it works, and why your files stay private
Everything runs inside your browser tab. Images are decoded and re-encoded locally with WebAssembly codecs, and downscaling uses Lanczos-3 resampling, a method that weighs surrounding pixels so edges stay crisp rather than going soft or jagged. If an image is too large to decode into raw pixels this way, the tool falls back to the browser's Canvas scaler. Single files can be up to 70 MB, and the output is capped at about 120 megapixels.
Nothing is sent to a server, which is why a passport scan or ID card is safe to process here. You can check this yourself: open your browser's developer tools, switch to the Network tab, resize an image, and watch that no upload request appears. After the page has loaded, the resizing keeps working with the network turned off.
Common jobs with a ready-made preset
If you already know the target, a preset fills in the dimensions, unit and file size for you:
- Resize to 20 KB, 50 KB, 100 KB or 200 KB for application forms and portals.
- Passport photo and ID card sizes.
- Instagram, LinkedIn, WhatsApp and YouTube thumbnails.
- E-commerce product photos, blog images and resume photos.
The Quick Presets directory lists more than 1,500 of these, from exact pixel sizes to paper formats. Got a whole folder of photos? Use the bulk image resizer to process up to 10 at once and download a ZIP.
Tips for better results
- Always resize from your original file. Resizing a copy that was already shrunk, then enlarging it again, cannot recover lost detail.
- Downscaling looks good; upscaling does not. Enlarging past 100% only interpolates, so expect softness.
- Keep the aspect ratio locked unless you need an exact shape. To change the shape without distortion, crop first, then resize.
- Use JPG for photos and PNG for graphics with sharp text or transparency. Using the wrong one is the commonest cause of oversized files.
- Check the result at 100% zoom before submitting anything to a form with a strict spec.
Frequently Asked Questions
Got questions about resizing or compressing images? Here are clear, straightforward answers: