Conversion Form

MM
CH

About the Unit

Millimeter (mm): The millimeter (mm) is a physical unit of measurement, 1/10th of a centimeter. Like cm, mm is commonly used in graphic design and printing, where precise physical measurements are needed. In CSS, mm is useful for defining width, height, and other dimensions of elements in layouts that will be printed or converted to other physical formats. Using mm is an effective way to ensure precise and consistent layout dimensions during the printing process. For digital designs, the mm unit may be less practical, as most web interfaces benefit more from relative units to ensure a more adaptive user experience. However, for technical documents or precision graphics, mm may be the best choice.

Pro Tip: mmch

Use mm for precise measurements in print, ch for text widths.

Quick Reference: Unit Conversion by Tens

MMCH
10mm0.787402ch
20mm1.574803ch
30mm2.362205ch
40mm3.149606ch
50mm3.937008ch
60mm4.724409ch
70mm5.511811ch
80mm6.299213ch
90mm7.086614ch
100mm7.874016ch
110mm8.661417ch
120mm9.448819ch
130mm10.23622ch
140mm11.023622ch
150mm11.811024ch
160mm12.598425ch
170mm13.385827ch
180mm14.173228ch
190mm14.96063ch
200mm15.748031ch
210mm16.535433ch
220mm17.322835ch
230mm18.110236ch
240mm18.897638ch
250mm19.685039ch

Live Unit Preview

See how different CSS units affect the size of the box below:

10px

10rem

10em

10%

10vw

10vh

Common Mistake

Be cautious when mixing mm and ch without testing on different screen sizes.

Real Code Example

/* Mobile-first card with mm → ch */
.card {
  padding: 0mm;     /* undefinedch */
  font-size: 1.5rem;
  width: min(90vw, 40ch);
}
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  • Esc: Reset values

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