Formula
The exact inches are rounded onto an eighth-inch grid:
inches = round(pixels / DPI × 8) / 8
The print-size page leaves the division unsnapped. A single edge without snapping is the pixel-to-inch page.
Assumptions
- The shop orders in eighths of an inch.
- Both sides use the same DPI.
- Rounding is to the nearest eighth, not always up.
Worked example
2,500 by 3,200 pixels at 300 DPI order as 8.375 × 10.625 in.
Input definitions
- Eighth of an inch
- 0.125 in. The size a shop can cut without a finer fraction.
- Shop size
- Both edges after that rounding.
Limitations
This is a planning figure from the numbers you type. It is not a measurement of a network, a camera, a printer, or a power supply.
Questions
Why is 2500 pixels not 8.333 inches?
8.333 rounds to 8.375, which is 8 and three-eighths. The print-size page would have left the 8.333.
What about centimetres?
The pixels-to-centimetres page multiplies the unsnapped inches by 2.54.