How do I resize an image in pixels, percent or cm?
To resize an image, open FixDoks's Resize Image tool, add your photos and choose pixels, percentage, or centimetres, millimetres or inches at a chosen DPI. Type the new width or height and the aspect ratio adjusts the other side automatically. The tool works on JPG, PNG, WebP, GIF, BMP and HEIC files in your browser, with no upload.
Resize Image at a glance
| Input | JPG, PNG, WebP, GIF, BMP, HEIC |
|---|---|
| Output | Resized image, same or chosen format |
| Processing | In your browser; your files are not uploaded |
| Price | Free, no watermark |
| Download | Free Google sign-in |
| Works on | Chrome, Edge, Safari and Firefox on Windows, Mac, Android and iPhone |
How to use Resize Image
- Click Select images and add one photo or many.
- Pick how to resize: Pixels, Percentage or cm / mm / inch. Keep aspect ratio is on, so photos are never stretched.
- Optionally choose a common size such as an Instagram post or YouTube thumbnail, and an output format.
- Click Resize images and download each file or all of them as a ZIP.
Three ways to set the new size
Pixels
Type the width or the height and the other value follows automatically, so the picture keeps its shape. Untick Keep aspect ratio if you need an exact box like 1280 by 720, but note the image will stretch if the proportions differ. To change the shape without stretching, crop it to the right ratio first. When you resize several photos at once with aspect ratio on, every photo gets the width you entered and its own matching height.
Percentage
50% halves both width and height, which makes the image a quarter of the pixels. This is the quickest way to shrink a batch of camera photos for email.
Centimetres, millimetres and inches
Print sizes only make sense together with a resolution, measured in dots per inch (DPI). A photo that is 3.5 cm wide at 300 DPI is 413 pixels wide. Choose the unit, enter the size and pick the DPI; the tool shows the pixel size it will create. JPG files also get the DPI written into the file, so print software and many form checkers read the intended physical size correctly.
| Common need | Setting |
|---|---|
| Passport photo, India / UK / EU | 3.5 × 4.5 cm at 300 DPI (413 × 531 px) |
| US passport photo | 2 × 2 inch at 300 DPI (600 × 600 px) |
| 4 × 6 inch print | 6 × 4 inch at 300 DPI (1800 × 1200 px) |
| A4 at print quality | 21 × 29.7 cm at 300 DPI (2480 × 3508 px) |
Resizing and quality
Making an image smaller is safe: FixDoks scales large photos down in steps, which keeps edges crisp and avoids the jagged look of a single big jump. Making an image larger cannot add detail that was never captured, so a small image enlarged a lot will look soft. For a modest increase, up to about 150%, the result is usually fine.
Resizing is not the same as compressing
Resizing changes the number of pixels. Compressing changes how efficiently those pixels are stored. If a form asks for a file size in KB, use the image compressor or a preset such as compress to 100 KB. If it asks for an exact pixel size and a KB range, like exam forms do, the govt form tools handle both at once.
Batch resizing tips
When you add many photos with different shapes, keep aspect ratio on and enter just the width. Portrait and landscape photos each get the right height. If you need every image in exactly the same box, for example product photos for an online store, crop them to the same ratio first, then resize.