Paper Size Converter: Millimeters, Inches and Points
Convert a width and height between millimetres, centimetres, inches and PDF points. Choose a nominal paper preset or enter a custom rectangle. This changes the units of a measurement; it does not edit a PDF, resample an image or send a file to a printer.
Convert your dimensions
Worked example: Letter in points
Enter width 8.5, height 11 and select Inches. The result is 215.9 × 279.4 mm and 612 × 792 PDF points. A PDF point is 1/72 inch, so 8.5 × 72 = 612. These are page dimensions, not image resolution.
How presets behave
Selecting a preset enters its two dimensions in millimetres and sets the input unit accordingly. Editing a dimension or unit changes the selector to Custom. This prevents an altered rectangle being presented as a standard sheet.
Width and height follow the orientation entered. A landscape Letter page can be entered as 11 × 8.5 inches; the same sheet has simply been rotated. ISO B5 and JIS B5 are separate presets because they have different dimensions.
Calculation method and rounding
One inch is exactly 25.4 mm; one centimetre is 10 mm; one PDF point is 25.4 ÷ 72 mm. The converter first expresses both dimensions in millimetres, then divides by the required unit factor. The displayed values round to at most three decimal places. Nominal standard sizes do not describe manufacturing tolerances or a printer’s usable region.
For example, 210 mm ÷ 25.4 = 8.267716… inches. An output of 8.268 inches is a rounded display of that value. Converting a rounded value back can introduce a small difference; retain the original measurement for precision work.
Choose the right tool for the job
- Pixels: use the image print-size calculator. A physical sheet has no fixed pixel count.
- Paper substitution: use the format comparison to inspect shape and whole-sheet fit.
- Changing a PDF: follow the PDF resizing guide. Expressing A4 in inches does not turn it into Letter.
- Measured templates: use Actual Size printing and check a reference after printing.
Inputs and limitations
Enter positive finite numbers. Empty, zero, negative or unsupported-unit inputs do not produce a result. The tool works with numeric dimensions only and does not upload a document. It cannot identify the sheet loaded in your printer or correct a driver setting.
References
NIST length units support the inch conversion; ISO 216 identifies the A- and B-series standard. The examples and implementation here are PaperGridly calculations.