Convert points to inches

The point (pt) is the unit for font size, line spacing and other small distances on a printed page. Word, desktop publishing programs and CSS all use the desktop publishing point, defined as exactly 1/72 of an inch, which is 0.3528 mm[1]. Twelve points make a pica and six picas make an inch, the relationship the pica to px converter builds on.

The inch has been exactly 25.4 mm since the international yard was adopted in the 1950s and 1960s[2]. In the US it is the everyday unit for paper, margins and book sizes, and the inches to cm converter takes it into metric.

Because the point is defined through the inch, the two convert without rounding: 72 pt is 1 in, 36 pt is half an inch and 18 pt a quarter. Screens follow a different rule, where 1 pt is 1.333 px, and the pt to px converter covers that case.

Divide the number of points by 72: inches = pt ÷ 72. One point is 0.0139 in, and 12 pt, the usual size for body text in documents, is 12 ÷ 72 = 0.1667 in, one sixth of an inch.

Microsoft Office works with the same ratio. The documentation of Word's InchesToPoints function states 1 inch = 72 points[3]. Excel measures row height in points, so the default row of 15 points is 0.2083 in tall and the maximum of 409 points is 5.6806 in[4].

When you start from inches, for a margin or a page size, the inches to pt converter does the multiplication by 72.

A 12 pt font sits on a body 0.1667 in tall, but the letters themselves are smaller. The point size measures the em square, the imaginary box each character is designed in, and says nothing fixed about any visible part of a letter[1].

How much of that box the letters fill depends on the typeface. We read the cap height stored in the font files supplied with Windows 11: in Arial capitals take up 71.6% of the point size, in Times New Roman 66.2% and in Calibri 63.2%. At 12 pt that gives capitals 0.119 in, 0.11 in and 0.105 in tall, which is why two fonts set at the same size can look noticeably different. To see the same font sizes in millimetres, use the pt to mm converter.

The same percentages work in the other direction, for a sign or a label where the letters must reach a given height. Divide 72 by the capital share of the typeface: capitals 1 in tall need about 101 pt in Arial and about 109 pt in Times New Roman.

The Point type selector under the fields switches between three definitions of the point. Leave PostScript (DTP), the default, for anything from Word, InDesign, a PDF or CSS, because all of them count 72 points to the inch.

Printer's (TeX) is 1/72.27 in. It is practically the American point that type founders adopted in 1886, which Donald Knuth fixed at exactly this value for TeX, where the 1/72-inch point is called the big point, bp[1]. Choose it for a length taken from a LaTeX file: 72 pt there is 0.9963 in, and it takes 72.27 pt to make an inch.

Didot is the traditional continental European point of 0.376065 mm[1]. It is 6.6% larger than the PostScript point, so 72 Didot points come to 1.066 in. You will meet it in older European typesetting and in TeX as the unit dd.