keisoku

Optimal Image Resolution for Print

Calculate the image resolution (width × height in pixels and total megapixels) needed to print sharply at a given paper size and dpi, including L size, A4, and A3.

Input

Find the image resolution (pixel count) you need from your target paper size and print resolution (dpi). Use it as a guide for capture/scan settings or to check whether a photo will print cleanly.

Paper size

Orientation

Resolution (dpi)

Preset
dpi

Result

Required resolution (350 dpi)

1,226×1,750px

About 2.1 megapixels total (2,145,500 px)

Width in pixels

1,226 px

Height in pixels

1,750 px

Total pixels

2.1 MP

Calculation breakdown

ItemValue
Paper dimensions (W × H)89 × 127 mm
Resolution350 dpi
Width in pixels1,226 px
Height in pixels1,750 px
Total pixels2,145,500 px（2.1 MP）

How it works

  • Pixel count is found with 'inches × dpi'. Divide each paper dimension (mm) by 25.4 to convert it to inches, then multiply by the resolution (dpi) to get the width and height in pixels.
  • Choose the resolution by use case: about 350 dpi for commercial printing and high-quality photo prints, 300 dpi for general home-printer output, and around 72 dpi for screen display.
  • Total pixels (megapixels) is calculated as 'width in pixels × height in pixels ÷ 1,000,000'. If your image meets or exceeds this value, it should print with enough detail at that paper size.
  • Switching the orientation (portrait or landscape) swaps the width and height. Choose landscape if you want to print in a wide layout.
  • Select 'Custom size (mm)' to enter non-standard paper or a finished size after cropping in millimeters.
  • Actual printing involves image scaling and printer processing, so treat the result as a guideline for the resolution you need.
  • L size and 2L size are common Japanese photo print formats (89 × 127 mm and 127 × 178 mm).