Formula and method
PPI describes how many image pixels are placed in one inch of print. Printer DPI describes ink dots and is not the same measurement, although “DPI” is often used informally for both.
Assumptions and limits
- The image is not upscaled or cropped after calculation.
- Quality labels are general guidance; subject detail and viewing distance also matter.
- Printer margins and bleed are not subtracted.
Worked examples
3000 × 2400 pixels at 300 PPI
The print is exactly 10 × 8 inches, or 25.4 × 20.32 cm. This is a strong density for close-viewed photo prints.
6000 × 4000 pixels at 240 PPI
The result is 25 × 16.67 inches. At 240 PPI it is usually suitable for a detailed wall print.
Common print sizes and required pixels
| Print size | 300 PPI | 240 PPI | 150 PPI |
|---|---|---|---|
| 4x6 in photo | 1200 x 1800 px | 960 x 1440 px | 600 x 900 px |
| 5x7 in photo | 1500 x 2100 px | 1200 x 1680 px | 750 x 1050 px |
| 8x10 in photo | 2400 x 3000 px | 1920 x 2400 px | 1200 x 1500 px |
| A4 paper | 2480 x 3508 px | 1984 x 2806 px | 1240 x 1754 px |
Frequently asked questions
Should I use DPI or PPI for image size?
Use PPI for pixels per printed inch. DPI is technically a printer’s ink-dot resolution.
Can I print larger than the calculated size?
Yes, but the effective PPI falls. Upscaling may help, but it cannot recreate all missing source detail.
Is 300 PPI always required?
No. 300 PPI is strong for close-viewed photos. 240 PPI is often very good, while 150 PPI can work for posters viewed farther away.
Does the calculator include margins or bleed?
No. It reports the image area. Add printer margins, trim and bleed requirements separately before production.