DPI vs Pixel Dimensions: What's the Difference?
Pixel dimensions are the actual size of the picture. DPI only says how those pixels map to inches or millimetres. If a form gives a print size and a DPI, pixels = size × DPI.
The relationship
- Pixels are real. They are the picture’s width and height.
- DPI is a conversion factor between pixels and physical size: pixels per inch.
So:
pixels = inches × DPI pixels = millimetres ÷ 25.4 × DPI
If a form gives a physical size and a DPI, it is really asking for a pixel size.
Conversion table
| Size | At 200 DPI | At 300 DPI |
|---|---|---|
| 2 × 2 inches | 400 × 400 | 600 × 600 |
| 35 × 45 mm | 276 × 354 | 413 × 531 |
| 3 × 3 cm | 236 × 236 | 354 × 354 |
| 6 × 2 cm | 472 × 157 | 709 × 236 |
Check yours with the formula, and round to whole pixels.
When the numbers in a notice disagree
Official notices don’t always agree with themselves, which is why it matters to know what a portal actually checks. In the IBPS recruitment notice for 2026-27 (as read on 7 October 2026), the photograph is described as 4.5 cm × 3.5 cm, and the preferred pixel size is 200 × 230. Those don’t describe the same shape or the same DPI: 3.5 cm is about 1.38 inches and 200 pixels across that is roughly 145 DPI, but 4.5 cm tall at 230 pixels is roughly 130 DPI. The notice marks the pixel size as “preferred”, and the file size range and format are what the form enforces.
The practical lesson is to match the pixel size the portal states, then the file size and format, and treat centimetres as a description. Check the current notification for your exam; requirements change.
What to do
- Work out the pixel size (formula or table above), or use the one the portal gives.
- Set the pixels, and the file size if there is a limit, with KB + Dimensions. Under Advanced you can add a DPI for JPG.
- If only the DPI tag is wrong, use Change DPI.
- Check everything with the Image Requirement Checker.
For what changes when you change only the DPI, see 72 DPI vs 300 DPI.