How many pixels is 3.5 × 4.5 cm? Photo sizes, DPI and what portals actually check
4 minutes, updated 2026-11-07
A form says the photograph must be 3.5 cm by 4.5 cm. A digital image has no centimetres; it has pixels. The bridge between them is resolution, written as DPI (dots per inch): how many pixels are printed across one inch of paper. Pick a DPI and the centimetres turn into a pixel size.
The formula
Pixels = inches × DPI, and inches = centimetres ÷ 2.54. So 3.5 cm at 300 DPI is 3.5 ÷ 2.54 × 300 = 413 pixels, and 4.5 cm is 531 pixels. At 200 DPI the same photo is 276 × 354 pixels. Both are 'correct'; the portal reads only the pixel count and the file size, and either passes if the notice gives no DPI. 300 DPI is the safe default because it is the print standard and gives a sharp image.
Common photo sizes in pixels
| Size | At 300 DPI | At 200 DPI |
|---|---|---|
| 3.5 × 4.5 cm (India, EU, UK) | 413 × 531 | 276 × 354 |
| 2 × 2 in (US passport, visa) | 600 × 600 | 400 × 400 |
| 3.5 × 3.5 cm (Korea, Japan small) | 413 × 413 | 276 × 276 |
| 4 × 6 cm | 472 × 709 | 315 × 472 |
| Signature 4 × 2 cm | 472 × 236 | 315 × 157 |
| A4 page | 2480 × 3508 | 1654 × 2339 |
What the portal actually checks
Almost no web form reads the DPI value stored in a file. It checks the pixel dimensions, the file size, the format, and sometimes the aspect ratio. That is why a photo exported at 72 DPI with the right pixel count passes, and a '300 DPI' photo with the wrong pixel count fails. When a notice gives centimetres and no DPI, use 300 and check that the resulting file size still fits the limit; if it does not, drop to 200 DPI rather than crushing the quality.
Aspect ratio
3.5 × 4.5 cm is a 7:9 ratio. A phone photo is 3:4 or 9:16, so the picture has to be cropped, not squeezed. The resize tool's 'crop to fill' option trims the long edges around the centre; use the crop tool first if the face is off-centre.