Typographic Unit Converter – Check All 18 Units

Type a number in the Convert from field and pick its unit from the list below it, then pick the unit you want below the Convert to field. The converter starts with DTP points and millimeters. The result appears as you type and works both ways: type a number in the Convert to field and the converter fills in the first one.

Em and rem have no fixed size, so picking em brings up a Parent font-size field below the fields, and picking rem brings up a Base font-size field. Both start at 16 px, the usual default font size in browsers[1]. With any other unit, these fields stay hidden.

You can also type the unit with the number, such as “12 pt”, “3 pc” or “1.5em” pasted from a stylesheet, and the converter picks that unit for the field. Typing just “12 points” sets the DTP point and tells you there is more than one kind of point. The Copy result button copies the number from the Convert to field, and Clear all empties both fields.

The point you use in Word, desktop publishing and CSS is exactly 1/72 inch[2], so one point is about 0.3528 mm. Word converts inches to points at the same 72 points per inch[3].

Before computers, printers in the United States worked with the American point system adopted by the type founders in 1886, which TeX still uses: 72.27 points to the inch[4], or about 0.3515 mm. Continental Europe used the larger Didot point, which the German standard DIN 16507 puts at 0.376065 mm[5]. The converter keeps each of these points, and two more Didot definitions, as separate units.

No. In TeX and LaTeX, pt is the American point (72.27 per inch), while the 1/72 inch point of PostScript and Word is called bp, for “big point”[4]. A 12 pt font in LaTeX is 4.218 mm, and 12 pt in Word is 4.233 mm, a difference of about 0.4%.

TeX has units for the Didot system too: dd is the Didot point and cc the cicero, 12 dd. Knuth defines the Didot point by the ratio 1157 dd = 1238 pt[4], which gives 0.3760650 mm, the DIN value to seven digits. TeX also has the scaled point, sp: 65,536 sp make one TeX point.

In CSS, em is the font-size of the element it is used on, and rem is the em of the root element, html[2]. When nobody changes the font size, a browser usually uses 16 px, so 1 em and 1 rem are both 16 px[1], or 12 pt.

In the font-size property itself, em is based on the parent: with a 20 px parent, 1.5em is 30 px, while rem still follows the html element. The Parent font-size field takes 1 to 200 px and Base font-size takes 1 to 100 px, the same as on the em to px and rem to px pages.

A CSS pixel is always 1/96 inch, which is 0.75 pt[2]. For screen pixels at any DPI, use the pixels and DPI converter.

The new Didot point (nd) is exactly 0.375 mm and the new cicero (nc) 12 nd, or 4.5 mm. ISO proposed this metric point in 1975, and pdfTeX has supported it since version 1.30.0[8].

Japanese and German standards chose a 1/4 mm module instead of a point[5]. CSS has it as the quarter-millimeter (Q), a fortieth of a centimeter[2], so a 16 Q font is 4 mm.

A twip is a twentieth of a DTP point, so an inch has 1,440 twips. The old Word format (.doc) stores margins and page sizes in twips[9], and in the XML of .docx files the same twentieth of a point is called dxa[10].