When do I need 300 DPI vs 150 DPI for printing?

300 DPI targets a viewing distance of roughly 11.5 inches — close, deliberate examination, like a photo book or an 8x10 on a desk. 150 DPI targets roughly 23 inches, double the distance, appropriate for a print hung on a wall and viewed from a few feet back rather than held in your hands. Choose based on how close a viewer will actually stand, not on print size alone.

Why Doubling the Distance Exactly Halves the Requirement

The underlying visual-acuity math (required PPI ≈ 3438 ÷ viewing distance in inches) is a simple inverse relationship, so doubling viewing distance exactly halves the pixel density needed to look equally sharp — which is precisely why 150 DPI sits at roughly double 300 DPI's target distance rather than being an arbitrary, unrelated second number.

Why Print Size Alone Doesn't Tell You Which to Use

A small print can still need 150 DPI's more relaxed target if it's mounted somewhere viewers naturally stand back from, like high on a wall or behind glass at a slight distance — and a large print can need something closer to 300 DPI if it's specifically designed for close inspection, like a gallery piece meant to reward examining fine detail. Viewing context, not physical print dimensions, is the variable that actually determines which target applies.

Get the exact target PPI for any viewing distance, not just these two reference points, in the Print Size / DPI Calculator.