To convert millimeters to InDesign pixels, this calculator computes the pixel dimensions a placed image needs to achieve a target effective PPI at the image's print size on the InDesign page.
Enter the mm value
Enter the physical dimension in millimeters — this is the size the image will occupy on your InDesign layout. For example, a full-bleed A4 cover image is 216 × 303 mm including 3 mm bleed on each side.
Select the DPI
Select the target PPI. InDesign's Preflight and Links panels show effective PPI for each placed image. For commercial offset printing, 300 PPI is standard. For newspaper or large-format, 150 PPI may be sufficient.
Read the pixel result
Read the pixel result. This is the minimum pixel dimension your source image must have so that, when placed at the specified size in InDesign, the effective PPI reaches your target. InDesign's Links panel will confirm this value.
InDesign itself works in physical units — pages, margins, and frames are sized in millimeters, not pixels. But every placed raster image has an effective PPI determined by its pixel dimensions divided by its placement size. This calculator tells you the pixel dimensions needed to hit your target PPI at a given mm size.