Photo Dimensions Converter: how to use it

A digital photo is measured in pixels, but a printed photo or an application form is measured in millimetres, centimetres or inches. The link between them is resolution, written as DPI (dots per inch). This converter does the arithmetic in both directions so you can move between a form's physical size and the pixel size you need to export.

It is a calculator only. It does not open or change any image.

How to use the Photo Dimensions Converter

1. Set the Resolution (DPI). Use 300 for print-quality work, or the DPI your requirement states.
2. Choose the Physical unit: millimetres, centimetres or inches.
3. To get pixels, type the physical Width and Height and press Convert physical to pixels.
4. To get a printed size, type the Width and Height in pixels and press Convert pixels to physical.
5. Copy the result into the Image Resizer or Passport Photo Resizer.

Tips for better results

• 35 x 45 mm at 300 DPI is about 413 x 531 pixels. 2 x 2 inches at 300 DPI is exactly 600 x 600 pixels.
• Lower DPI gives fewer pixels for the same print size. 35 x 45 mm at 150 DPI is only about 207 x 266 pixels.
• Round to whole pixels; fractions of a pixel do not exist in an image.
• If a form states only pixels, you can ignore DPI completely.

The formula

Inches = pixels / DPI. Millimetres = inches x 25.4. Centimetres = inches x 2.54. Going the other way, pixels = (physical size / unit factor) x DPI. For example, 600 pixels at 300 DPI is 2 inches, which is 50.8 mm.

Frequently asked questions

Does DPI change a photo's pixels?

No. DPI is just a label that says how densely those pixels should print. The pixel dimensions are what portals check.

Which DPI should I use for a passport photo?

300 DPI is the usual standard for printing. Follow your application's instructions if it names another value.

Is any image uploaded?

No image is involved. Only numbers you type are used.

Open the Photo Dimensions Converter →

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