MM to REM Converter
Use this free online mm to rem converter tool to convert millimeters to root em units. Millimeters are a precise metric unit while REM is a scalable web unit. This converter enables precise metric measurements to work with responsive web designs.
To convert millimeters to rem, first convert to pixels (mm × 96 ÷ 25.4), then divide by the root font-size. The default root font-size is 16px. This bridges precise metric measurements with scalable typography.
Conversion Formula
rem = (mm × 96 ÷ 25.4) ÷ root font-size
For example, to convert 25.4mm (1 inch) to rem with 16px root font-size, calculate (25.4 × 96 ÷ 25.4) ÷ 16 = 6rem. Similarly, 12.7mm equals 3rem.
MM to REM Converter Conversion Table (Root: 16px)
| MM | REM |
|---|---|
| 1mm | 0.2362rem |
| 2mm | 0.4724rem |
| 5mm | 1.181rem |
| 10mm | 2.362rem |
| 15mm | 3.543rem |
| 20mm | 4.724rem |
| 25.4mm | 6rem |
| 30mm | 7.087rem |
| 40mm | 9.449rem |
| 50mm | 11.81rem |
| 75mm | 17.72rem |
| 100mm | 23.62rem |
| 127mm | 30rem |
| 150mm | 35.43rem |
| 200mm | 47.24rem |
| 254mm | 60rem |
What is MM?
Millimeters (mm) are an absolute CSS unit representing physical millimeters, primarily used for precise print measurements. In web contexts, 1mm equals approximately 3.78 pixels. Millimeters are most useful in print stylesheets and international design contexts where metric precision is required.
What is REM?
REM (Root EM) is a relative CSS unit based on the root element's font size, typically 16px by default in most browsers. Unlike EM units which cascade based on parent elements, REM provides consistent sizing throughout the document. This makes REM ideal for creating scalable, accessible designs that respect user font-size preferences.