What size in pixels is a 4x6 photo?

At 300 PPI, the usual target for photo prints, a 4x6 print needs 1200 × 1800 pixels. A 5x7 needs 1500 × 2100, and an 8x10 needs 2400 × 3000. Any recent iPhone photo has more pixels than that; the real problem is the shape.

Pixels for common print sizes

Print	Ratio	At 300 PPI	At 200 PPI
4 × 6 in	2:3	1200 × 1800	800 × 1200
5 × 7 in	5:7	1500 × 2100	1000 × 1400
8 × 10 in	4:5	2400 × 3000	1600 × 2000
10 × 15 cm	2:3	1181 × 1772	787 × 1181

DPI and PPI

• PPI (pixels per inch): how many image pixels go into each printed inch.
• DPI (dots per inch): how many ink dots the printer lays down. A printer uses several dots per pixel.

The DPI number stored in a file is only a label. What matters is the pixel count divided by the print size. 1800 pixels across 6 inches is 300 PPI whatever the label says.

Crop first, or the lab will

An iPhone shoots 4:3. A 4x6 print is 2:3, longer and thinner. If you send 4:3 photos, the lab trims the long edges or adds white bars. Crop to 2:3 yourself and you decide what’s lost.

Prepping a batch

In Batchly (my app):

1. Pick the photos.
2. Crop to a custom 2:3 ratio.
3. Resize to 1800 px on the long edge for 4x6 (or skip resizing; most labs accept larger files).
4. Convert HEIC to JPEG, which every print service accepts.

Batchly changes pixels, crop and format. It doesn’t set the DPI label in the file, and doesn’t need to for the reasons above.

Related: crop multiple photos at once, HEIC to JPG and the Batchly guides.