Photo quality guide

How many pixels does a small photo print need?

Start with two numbers: the pixels in your image and the size you want on paper. A file's size in megabytes, or a label saying “300 DPI,” cannot tell you whether a particular crop has enough detail. Smaller prints use the same pixels over less paper, so they can look sharper than larger versions of the same image.

PPI describes the image; DPI describes the printer

PPI means pixels per inch at a particular printed size. DPI refers to the printer's dots per inch. A printer's advertised 1,200 DPI setting does not turn a small source image into a 1,200 PPI photograph. Adobe distinguishes these measurements in its printer-resolution guidance.

Changing only the resolution label does not add image detail. Pixel dimensions and print dimensions determine the density; Adobe's printed-resolution explanation describes this relationship.

Useful planning targets

The table uses 300 PPI as a planning target, not a pass-or-fail rule. Values are rounded up to whole pixels and assume the source or final crop matches the printed shape. For example, 40 ÷ 25.4 × 300 = 472.44, rounded up to 473 pixels.

Account for the fit mode

Consider a 1,200 × 800 pixel landscape image in a 50 × 50 mm frame. The two fit choices use the source differently:

These are the contain and cover behaviors described in MDN's object-fit reference. Calculate from the pixels that remain after cropping. Do not divide the original 1,200 pixel width by the square's width for Fill the frame; that would overstate the available detail.

Read the source PPI note, then inspect the picture

1. Select the original file. A thumbnail or messaging-app copy may contain fewer pixels. More pixels cannot repair a photo that was already out of focus.
2. Set the intended size and fit. Select the photo and read its source PPI note after changing dimensions or switching modes.
3. Reduce the print size if needed. For example, a 300 × 450 pixel picture supplies only 150 PPI at 2 × 3 inches, but 300 PPI at 1 × 1.5 inches. Choose the tradeoff that fits your journal.
4. Inspect the PDF and make one test print. Check faces, fine text, and dark areas. A resolution calculation is not a guarantee of sharpness or color accuracy.

Source PPI is not the exported PDF's resolution. The tool prepares photo rasters at up to about 300 PPI and can reduce them further for large frames to limit browser memory. It does not enlarge a low-resolution source to manufacture detail. A 406 PPI source therefore does not mean the PDF retains 406 PPI.

You can inspect a real sample PDF rendering and its mixed frame sizes before using your own images. The sample illustrates layout; it is not proof of photographic detail or a physical printer test. If your print dimensions change, use the 100% printing guide before evaluating sharpness.