Enter the physical sheet’s width and height and choose the original unit. The result supplies millimeters, inches and area. It does not alter an image, PDF or printer setting.
Formula and example
1 inch = exactly 25.4 mm. 1 cm = 10 mm. Area in square meters = width in mm × height in mm ÷ 1,000,000. A US Letter sheet entered as 8.5 × 11 inches converts to 215.9 × 279.4 mm. An A4 sheet entered as 210 × 297 mm has area 0.06237 m².
Dimensions do not establish compatibility
A manufacturer may round dimensions on a printer display. Custom-size feed limits, printable margins, borderless modes and the scan area are different properties. Do not use this conversion to infer an undocumented input size or a safe cardstock weight.
The display rounds values for readability while calculations use full numeric precision. A-series values in the separate reference are nominal millimeters, so their inch figures are approximations. For dimension-sensitive labels or forms, use the correct document size and a controlled actual-size proof. NIST documents the exact inch definition.