Photo Resolution for Printing: How Many Pixels Do You Need?

DPI in a nutshell

DPI (dots per inch; in practice, pixels per inch) tells you how many pixels in a photo fit into each inch (2.54 cm) of paper. The same 1200 × 1800-pixel photo can be printed at 10 × 15 cm at 300 DPI for a sharp result, or at 20 × 30 cm at 150 DPI for a softer look. The pixel dimensions stay the same; DPI depends on the print size.

So the right question isn’t “Is my photo 300 DPI?” but “Does my photo have enough pixels for the size I want to print?”

How many pixels you need for each print size

A widely accepted guideline for photos viewed up close (albums, frames, and ID photos) is 300 DPI. The calculation is: centimeters ÷ 2.54 × 300. Here are some common print sizes, already calculated:

• 3 × 4 cm (small ID photo): about 354 × 472 pixels.
• 10 × 15 cm: about 1181 × 1772 pixels.
• 13 × 18 cm: about 1535 × 2126 pixels.
• 20 × 30 cm: about 2362 × 3543 pixels.
• A4 (21 × 29.7 cm): about 2480 × 3508 pixels.

Any modern phone camera captures far more pixels than that. Problems are more likely with photos received in messages, screenshots, and images downloaded from the internet, which are often much smaller.

When you can use a lower resolution

• 150 to 200 DPI usually works well for larger photos viewed from about arm’s length.
• Posters and banners are viewed from farther away, so much lower resolutions can work. A print shop can recommend the minimum for each size.
• Text and fine lines need more resolution than photos of people and landscapes because jagged edges are easier to see.

Below about 100 DPI at the final print size, most people start to notice that the image looks blurry or pixelated.

How to check your photo

1. Open your photo in Image Size and Details and note its width and height in pixels.
2. Divide each dimension by the desired print size in inches (centimeters ÷ 2.54). The result is the DPI you’ll get.
3. Example: an 800 × 1200-pixel photo printed at 10 × 15 cm gives you about 203 DPI. That’s reasonable. The same photo at 20 × 30 cm drops to about 102 DPI and will look soft.

The DPI value stored in the file (often 72 or 96) is just a label and doesn’t indicate quality. The pixel dimensions are what matter.

Photo is too small: what to do

• Find the original. Photos sent through WhatsApp as regular images are compressed and resized. Ask the sender to resend the photo as a document to preserve the original file.
• Print it smaller. This is the most straightforward fix: a 600 × 900-pixel photo looks great at 5 × 7.5 cm.
• Adding pixels doesn’t create detail. Resize image can enlarge a photo, and some print shops require a minimum pixel size. Enlarging it meets the technical requirement, but the photo still has the same amount of detail—it just looks bigger and softer.

Small ID photos for printing at home or at a print shop

For ID photos, ID Photo Maker lays out photos at the right size on a 10 × 15 cm or A4 sheet, ready to print at any photo lab. Use the original photo from your phone—not one received in a message—to get a sharp result. For step-by-step instructions, see How to Make an ID Photo at Home.

Frequently asked questions