Passport photo size in mm, inches and pixels: how to convert
Millimetres and inches describe a printed size, pixels describe a digital one, and the link between them is pixels per inch. The formula is simple: pixels equal millimetres divided by 25.4, multiplied by pixels per inch.
Open the photo toolThe formula
One inch is exactly 25.4 millimetres. So to turn a physical size into pixels:
pixels = millimetres ÷ 25.4 × pixels per inch (ppi)
The ppi value is your choice, not a property of the photo. 300 ppi is the standard for print and for most upload rules that quote a physical size.
Two common passport photo sizes
| Size | Millimetres | Inches | Pixels at 300 ppi | Pixels at 600 ppi |
|---|---|---|---|---|
| 35 × 45 mm (width × height) | 35 × 45 | 1.378 × 1.772 | 413 × 531 | 827 × 1063 |
| 2 × 2 in (US) | 50.8 × 50.8 | 2 × 2 | 600 × 600 | 1200 × 1200 |
Pakistan’s online passport page asks for a photo 45 mm high by 35 mm wide, which is the first row. The US visa digital standard accepts squares from 600 × 600 to 1200 × 1200 pixels, which matches the second row at 300 and 600 ppi. A scanned 2 × 2 inch print at 300 ppi gives exactly 600 × 600 pixels.
Worked example: 35 × 45 mm at 300 ppi
- Width: 35 ÷ 25.4 = 1.378 inches. Multiply by 300 to get 413.4, which rounds to 413 pixels.
- Height: 45 ÷ 25.4 = 1.772 inches. Multiply by 300 to get 531.5, which rounds to 531 or 532 pixels.
- Check the proportions: 35 ÷ 45 = 0.778 and 413 ÷ 531 = 0.778. They match, so the photo is not stretched.
Common mistakes
- Mixing up width and height. 35 × 45 mm is 35 wide and 45 high, a portrait shape. Write them in that order.
- Thinking the DPI tag changes the picture. A “300 DPI” label stored in the file does not change the number of pixels. Only the pixel width and height matter to an upload form that asks for pixels.
- Stretching to hit a size. Changing only the width or only the height distorts the face. Keep proportions locked, and crop first if the ratio is wrong.
- Rounding too early. Convert to pixels at the end. Rounding millimetres or inches first adds small errors.
A form that asks for “35 × 45 mm” without any pixel size is describing a printed photo. Check whether it wants a physical size, a pixel size or both before you resize. If both are given, the pixel size is what an upload page can measure.
Using SizeKit with these numbers
Open the photo resizer, enter the pixel width and height from the table, and set a KB limit if the form has one. SizeKit does not crop, so make sure the photo already has the right proportions. For other conversions use the length converter, which shows the working.
Remember that some official uploads do not want you to resize at all. For example, Pakistan’s passport page says not to use photos cut down from larger pictures. See that guide before you edit a passport photo.
Frequently asked questions
How many pixels is 35 × 45 mm?
At 300 pixels per inch it is about 413 × 531 pixels. At 600 ppi it is about 827 × 1063 pixels.
How many pixels is a 2 × 2 inch photo?
At 300 ppi it is 600 × 600 pixels. At 600 ppi it is 1200 × 1200 pixels.
Does DPI matter for an online upload?
Usually not. Upload forms measure pixel width, pixel height and file size. DPI only matters for printing or when a form states a physical size.