A7 at 96 DPI is 280 × 397 pixels

The working

Pixels are inches multiplied by the resolution, and an inch is 25.4 mm.

• Width: 74 mm ÷ 25.4 = 2.913 in; 2.913 in × 96 = 279.7, which rounds to 280 pixels.
• Height: 105 mm ÷ 25.4 = 4.134 in; 4.134 in × 96 = 396.9, which rounds to 397 pixels.

Bleed is extra image past the trim line, so that a cut that lands slightly off still leaves ink to the edge. Print shops usually ask for 3 mm on every side of an A-series page, which makes the file 302 × 420 pixels.

Is your photo big enough?

To fill A7 at 96 DPI an image needs at least 280 × 397 pixels. Cropped to fill the sheet:

• A 12 megapixel phone photo (4000 × 3000) gives 968 DPI: enough.
• A 24 megapixel camera photo (6000 × 4000) gives 1,373 DPI: enough.
• A 48 megapixel photo (8000 × 6000) gives 1,935 DPI: enough.

At 96 DPI the pixels of a print blend together from about 35.8 inches (91 cm) away. 96 DPI is the reference resolution of Windows and of the web: CSS defines one inch as 96 pixels, so a web page sized in inches or millimetres is laid out at 96 pixels to the inch.