Resize an image in centimetres
Forms and printers ask for sizes in centimetres, and image files are measured in pixels. Type the width and height in cm, choose a DPI, and this page does the conversion and the resize.
- Runs in your browser
- Nothing is uploaded
- No sign-up
- Batch up to 20 images
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JPG · PNG · WebP · GIF · BMP · AVIF · SVG · up to 50 MB each · up to 20 files
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How to use the centimetre image resizer
Add the image, type the width and height in centimetres and choose the DPI. The picture is resized to the matching pixel size, for example 413 × 531 pixels for 3.5 × 4.5 cm at 300 DPI, and the DPI is saved in the file so it prints at that size.
- Add your imageThe fields show its current size in centimetres at 300 DPI.
- Type the size in cmEnter a width, a height or both, or tap a ready-made size such as 3.5 × 4.5.
- Choose the DPI and download300 suits printing. Use the figure your form states if it gives one.
About this tool
A size in centimetres only becomes a size in pixels once you add a resolution. A 3.5 × 4.5 cm photo is 413 × 531 pixels at 300 DPI and 276 × 354 pixels at 200 DPI. Both are correct; which one you need depends on what the form or the print shop asks for.
This page takes the two numbers you were given, the size in cm and the DPI, and works out the pixels. It then resizes the picture and writes the DPI into the file, so a program such as Word or a print dialog places it at the physical size you asked for. Leave the aspect ratio locked to scale the whole picture, or tap a ready-made size to crop to an exact shape.
What you get
- Width and height in centimetres, to two decimal places
- DPI presets from 72 to 600, or any value you type
- Saves the DPI in the JPG or PNG file
- Crop to fill, fit inside or stretch when the shape changes
- Batch up to 20 images to the same size
When to use the centimetre image resizer
Passport and visa photos
Many countries specify 3.5 × 4.5 cm. Enter that with the DPI the form states and the pixel size comes out right.
Exam and job application forms
Portals that list a photo size in centimetres alongside a resolution, such as 3.5 × 4.5 cm at 200 DPI, check the pixel size that pair works out to.
Prints for standard frames
10 × 15 and 13 × 18 cm are the common photo print sizes in countries that use the metric system.
Pictures for documents and posters
A layout that leaves an 8 × 6 cm gap for a picture is easier to fill when the image already has that size saved in it.
Common sizes in centimetres and their pixels
| Size | Used for | Pixels at 300 DPI | Pixels at 200 DPI |
|---|---|---|---|
| 2 × 2.5 cm | Stamp-size photo | 236 × 295 | 157 × 197 |
| 3.5 × 4.5 cm | Passport photo | 413 × 531 | 276 × 354 |
| 5 × 5 cm | Square visa photo | 591 × 591 | 394 × 394 |
| 10 × 15 cm | Standard photo print | 1181 × 1772 | 787 × 1181 |
| 13 × 18 cm | Larger photo print | 1535 × 2126 | 1024 × 1417 |
| 21 × 29.7 cm | A4 page | 2480 × 3508 | 1654 × 2339 |
How it works
The conversion is one line of arithmetic: pixels = centimetres ÷ 2.54 × DPI, because an inch is exactly 2.54 cm and DPI counts pixels per inch. The answer is rarely a whole number, so it is rounded to the nearest pixel. For 3.5 cm at 300 DPI the sum gives 413.39, which becomes 413 pixels, or 3.497 cm. That rounding is why the size can be off by a few hundredths of a millimetre, far less than a printer's own tolerance.
After resizing, the DPI you chose is written into the file: in the JFIF header of a JPG, or the pHYs chunk of a PNG. A picture encoded by a web browser, which is how online tools save their results, carries no usable resolution of its own, so a program opening it falls back on 72 or 96 DPI and shows the wrong physical size. With the value saved, 413 × 531 pixels opens as 3.5 × 4.5 cm. WebP output is not offered here because that format has no resolution field.
Common problems and how to fix them
- The edges of my photo were cut off
- The size you asked for has a different shape from the photo, and the default is to crop evenly from the centre to fill it. Pick "Contain (fit inside)" to keep the whole picture with a border, or tick "Lock aspect ratio" and enter only one side.
- The form says the dimensions are wrong
- It is checking pixels. Make sure the DPI here matches the one the form states: 3.5 × 4.5 cm is 413 × 531 pixels at 300 DPI but 276 × 354 at 200 DPI. If the form lists a pixel size, use the Image Resizer and enter the pixels directly.
- The result looks blurry
- The size and DPI you chose need more pixels than the original has, so it was enlarged. The result panel says by how much. Start from a larger original, or use a lower DPI if the form allows it.
- It prints at the wrong size
- Look for a "fit to page" or "scale to fit" option in the print dialog and switch it to actual size or 100%. Those options override the size saved in the file.
Frequently asked questions
How do I resize an image to 3.5 cm × 4.5 cm?
Add the photo, tap the 3.5 × 4.5 size and download. At the default 300 DPI the result is 413 × 531 pixels. The photo is cropped to that shape from the centre, so start with a picture where the face is in the middle, or position it first with the Passport Photo Cropper.
How many pixels is 1 cm?
It depends on the resolution: pixels = centimetres ÷ 2.54 × DPI. One centimetre is about 118 pixels at 300 DPI, 79 at 200 DPI, 38 at 96 DPI and 28 at 72 DPI.
Which DPI should I choose?
Use the one your form or printer states. If none is given, 300 DPI is the standard for photo printing, and 200 DPI is common on application portals. For a picture that will only be seen on a screen the DPI makes no visible difference; only the pixel count matters there.
Will the image print at exactly this size?
Yes, as long as the program printing it uses the resolution saved in the file and is not set to "fit to page". The pixel size is rounded to whole pixels, so the true size can differ from the one you typed by a few hundredths of a millimetre.
How do I convert cm to pixels?
Divide the centimetres by 2.54 and multiply by the DPI. For 10 cm at 300 DPI that is 10 ÷ 2.54 × 300 = 1181 pixels. You do not need to work it out here: the pixel size is shown with the result.
Can I set only the width and keep the proportions?
Yes. Leave "Lock aspect ratio" ticked and type one side. The other is filled in from the shape of your image, and nothing is cropped. To type both sides yourself, untick the lock first.
Why is WebP not offered as an output format?
Because a size in centimetres depends on the DPI being stored in the file, and WebP has no field for it. JPG and PNG both do, so those are the two formats on this page.