DPI vs PPI: what's the difference?
DPI and PPI get used interchangeably, but they describe different things — which is why so many '300 DPI' requests cause confusion. Here's what actually matters when you print.
At a glance
| PPI (pixels per inch) | DPI (dots per inch) | |
|---|---|---|
| Describes | How densely an image's pixels map onto paper | How many ink dots a printer lays down per inch |
| Stored in the image file? | Yes — the resolution tag, usually labelled DPI | No — it's a printer setting |
| Changes image quality? | No — only the print size, unless you resample | Depends on the printer hardware |
| Typical values | 72–96 (screen), 300 (print) | 300–2400+ for inkjet and laser printers |
The only formula you need
Print size = pixels ÷ PPI. A 3000 × 2000 pixel photo prints at 10 × 6.67 inches at 300 PPI, or about 31 × 21 inches at 96 PPI. The pixels are identical in both cases — only the physical size changes.
That's why changing an image to '300 DPI' doesn't add detail by itself. If the image doesn't have enough pixels for the size you want, you need to print smaller or accept a softer result.
How many pixels do you need?
| Print size | At 300 DPI | At 150 DPI |
|---|---|---|
| 2 × 2 in (5.1 × 5.1 cm) | 600 × 600 px | 300 × 300 px |
| 3.5 × 4.5 cm | 413 × 531 px | 207 × 266 px |
| 4 × 6 in (10.2 × 15.2 cm) | 1200 × 1800 px | 600 × 900 px |
| 5 × 7 in | 1500 × 2100 px | 750 × 1050 px |
| 8 × 10 in | 2400 × 3000 px | 1200 × 1500 px |
| A4 (21 × 29.7 cm) | 2480 × 3508 px | 1240 × 1754 px |
When does DPI matter?
- Printing: print shops use it to work out the physical size. 300 is the usual standard for photos and documents.
- Word, InDesign and similar apps: they use it to decide how large an image appears when you insert it.
- Screens and the web: it's ignored — browsers size images by their pixel dimensions.
- Forms that ask for 300 DPI usually want enough pixels for a sharp print at a stated size.
Tools used in this guide
Related guides
DPI vs PPI: what's the difference? — FAQ
Not technically. PPI is the pixel density stored with an image; DPI is the ink-dot density of a printer. In everyday use — and in most software — 'DPI' refers to the image's PPI value.