Convert point (computer) to millimeter [mm] • Typography and Digital Imaging Units Converter • Miscellaneous Converters • Compact Calculator • Online Unit Converters (2024)

Magnetic Flux

Did you know that the magnetic field viewing film can be used to show stationary and slowly changing magnetic fields? Click or tap to find out more!

Overview

Typography, the study of type, is concerned with the appearance of letters, including their shape, size, and color. It emerged around the invention of the printing press in the mid-fifteenth century. Arranging letters on the page well and following the principles of good typography can impact the reader and strengthen the message that the designer is trying to convey. Bad typography, on the other hand, can make the text difficult to read.

Fonts are classified into different types, such as serifs (fonts with decorative elements named serifs) and sans serifs (fonts without serifs). In the illustration, the first letter in blue is in a serif font, Bodoni. Here one of the four serifs is marked in red. The other letter in yellow is in a sans-serif font, Futura.

Other classifications divide fonts based on their historic origins: the old style or old face includes the oldest fonts; transitional types are the ones that historically followed the oldest ones; modern types are fonts that were designed after the transitional types and until about the 1820s; and modern types or modernized old-style types include modern fonts that imitate the true old style but are designed in the modern times. There are also other groups in this classification. Each group of fonts differs in several design elements such as in their thickness, contrast between thick and thin lines, and the shape of the serifs. Other classifications also exist.

Typography is concerned with manipulating size and font types to make pages with a pleasing and easy-to-read appearance. There are several conventions for specifying the size of letters. For some of these conventions, the same size of letters in two different fonts may not mean that they have the same linear dimensions, as described below. Despite these inconsistencies, size does help designers to know how much space a given text takes up on a page, and as such is a useful measure in desktop publishing.

Digital images are also measured in desktop publishing, to ensure that they fit well in the allotted space. While centimeters or inches can be employed, units called pixels are also used. Each pixel represents a dot (or a square) that makes up an image on the screen.

Definitions of Units

In typography, the size of letters and characters is measured with the help of a basic standardized unit, pica (pc). Sometimes pica is used directly, for example, to measure margins and column sizes. However, often instead of pica, the units derived from it, such as points, are used. There are several conventions for calculating pica.

The size of the letters is measured using the following dimensions (pictured):

1. ascender line: marks the top of the letter;
2. mean line: top of the main body of the letter, this is also known as median;
3. baseline: bottom of the main body of the letter;
4. descender line: marks the bottom of the letter;
5. x-height: the size of the main body of the letter, traditionally it is equal to the height of the letter x;
6. body size: the size of the lead block that was historically used for printing each letter.

Points (pt) are the units conventionally used to determine the size of the font. For example, much of the academic writing and business correspondence is done in sizes between point 10 and point 12. The value of one point is equal to 1/12 of a pica. The actual size in inches or millimeters refers to the value called body size, under number 6 in the illustration. Historically this is the physical height of the lead block used for printing with the printing press — it has a single letter on it. To visualize this, imagine a stamp with one letter on it — the point size would be not the size of the letter, but the physical height of the stamp. In web development, in particular, in LaTeX and CSS, x-height is sometimes used instead of points.

Pixels (px) are the units for measuring the size of digital images. See the description of the pixel below.

Different Units

There are several different conventions used to calculate the length of one pica. As the printing technology developed somewhat independently in different countries, so did the typographic units. They were commonly based on the local units of length, and even in cases when pica is tied to the inch, its value differs depending on the historical definition of the inch in a given country. The most commonly used computer pica was developed to answer the need for standardization across countries.

Computer Pica

Computer pica is measured as 1/6 of an inch. Points are generally derived from pica as described above. PostScript is one of the formats that use computer typography units. These units are used by most computers for measuring text displayed on the screen and for home printing.

In some cases, in web design, points can be defined based on the physical measurements of pica relevant to units of length (for example, inches, as outlined above). However, both points and picas can also be defined relative to the size of a pixel, as defined by a particular website. In this case, this pixel is called a reference pixel.

Reference Pixel

Standard pixels are substituted by reference pixels when the target audience uses devices that are viewed from unusual distances or that have screens of unconventional sizes. For example, the display of most smartphones assumes that the viewers use it at a distance of about 10 inches from the eyes (25.4 cm), but if a new smartphone is developed with the same screen size as most phones are today, but that is meant to be viewed at 5 inches (12.7 cm) distance instead, then the reference pixel should be about half of the size of the conventional pixel, to ensure that all the characters are displayed well and do not appear choppy or pixelated.

Visual Angle

People long noticed the correlation between these values: the size of the screen, the distance from the screen, the size of a pixel, and how big this pixel appears to the human eye. To relate all of them in an easy-to-understand way, the concepts of visual angle and Pixels Per Degree were introduced.

The variable Pixels Per Degree (PPD) represents the total number of pixels that one wants to appear on the screen per a given distance formed by the viewing angle of one degree. In the illustration, the yellow angle D is one degree (it is not actually one degree in this picture because it would be hard to see the diagram with such a small angle, but please imagine that it is). PPD is the number of pixels that can be lined up along the red line E and also along the red line F. In our case, PPD is three pixels (two grey and one dark grey). Display manufacturers usually calculate the PPD so that the pixels are small enough to blend in and to produce a continuous image. It is usually much higher than in our illustration. Apple, for example, claims to keep the PPD for their displays no lower than 53.53, sometimes as high as 79 PPD.

Knowing the PPD one can calculate the size of one pixel by using the distance from the eye to the display and the visual angle. In our example, the distances are 10 and 20 inches — the approximate distances for a smartphone and a computer display respectively. The visual angle is the angle at which the distance that is covered within this angle on the screen covers one pixel (green lines B and C on the illustration). In the illustration, the visual angle is marked in orange. Using these tools, we can easily calculate pixel sizes not only for standard displays but also for those that are viewed at unusual distances or are of unusual sizes.

If you are interested to know more, you can find more information on the W3C website.

Other Units

Other typography units are used in the industry, although much less commonly. American pica is one of them. It is about 0.166 of an inch. The printer’s pica is measured the same way.

Cicero still appears in literature occasionally. It was a unit commonly used in Continental Europe until pica was introduced. It is calculated as 1/6 of a French inch. French inches are different from the inches currently in use. One cicero equals 4.512 mm or 0.177 modern inches. It is very similar to the computer pica and is equal to about 1.06 computer picas.

Em and En

While the units outlined above mainly denote the height of each letter, em and en are two typographic units that measure the width of letters. Em equals the size of the character in points, while en is half of an em. Historically, the size of em was defined as the width of the capital letter M. This is not an accurate definition anymore, because M is different for the numerous fonts that are in use today.

Em and en are often used to measure the length of dashes. In English, the dash that is used to indicate the range (e.g. “use 3–4 tablespoons of sugar”) is called the en dash, while the longer dash used in punctuation (e.g. “the summer was short, but the winter — long”) is called the em dash. Indentation and column width can also be measured in these units.

Critique

Many designers argue that the currently used typographic systems based on picas and points are far from ideal. Critique includes problems that arise from having to use this system in conjunction with the metric or the imperial units that designers use for images and page sizes, etc. — this is a problem because the typographic unit system is not tied accurately to the metric or the imperial units.

Another problem is that the letters of the same point size but from different fonts appear to have different sizes. This is because the size expressed in points corresponds to the body size, not to the size of the body of the letter, which is the x-height on the illustration above. This makes it difficult for the designer to keep consistency throughout the document. For example, in the illustration, all three words are written with the same size in points, yet their x-height is very different because different fonts are used for them. Some designers propose to use the x-height as the font size and to stop using the body size to address this issue.

References

This article was written by Kateryna Yuri

You may be interested in other converters in the Miscellaneous Converters group:

Metric Prefixes Converter

Data Transfer Converter

Lumber Volume Measures Converter

Currency Exchange Rates

Men’s Clothing and Shoe Sizes

Women’s Clothing and Shoe Sizes

Compact Calculator Full Calculator Unit definitions

Online Unit Converters Miscellaneous Converters

Miscellaneous Converters

Converters of the measurement units used for measurement data transmission speed, lumber volume measurement and in typography and digital imaging. Description of metric prefixes and molar mass of compounds calculator.

Typography and Digital Imaging Units Converter

In typography, a point (pt) is the smallest unit of measure, being a subdivision of the larger pica. The point has long been the usual unit for measuring font size and distance between lines of text and other small items on a printed page. 1 point is equal to 0.35 to 0.38 mm depending on the country. In the late 1980s — the beginning of the 1990s the traditional point was replaced by the desktop publishing point (also called the PostScript point), which was defined as 1⁄72 of an inch (25.4⁄72 mm = 0.3527 mm). Twelve points make up a pica, six picas make an inch.

A cicero is a unit of measure that was used in traditional typography in Italy, France, and other continental European countries. 1 cicero = 12 points. It is not used in modern desktop publishing systems.

A pica is a typographic unit of measure corresponding to 1/72 of a foot or 1/6 of an inch. The pica contains 12 point units of measure. The contemporary pica used in DTP systems like Adobe InDesign and earlier in Aldus Pagemaker is 1/72 of a foot, i.e. 4.233 mm or 0.166 in.

A twip, which means “twentieth of a point” is a typographical measurement, defined as 1/20 of a typographical point. One twip is 1/1440 inch or 17.639 µm when derived from the PostScript point at 72 to the inch, and 1/1445.4 inch or 17.573 µm based on the printer’s point at 72.27 to the inch.

In digital imaging, a pixel (short for a picture element) is a physical point in a raster image, or the smallest, addressable element in a display device. In other words, a pixel is a single point in a picture. On the monitor of a computer, a pixel is usually a rectangle.

Using the Typography and Digital Imaging Units Converter Converter

This online unit converter allows quick and accurate conversion between many units of measure, from one system to another. The Unit Conversion page provides a solution for engineers, translators, and for anyone whose activities require working with quantities measured in different units.

You can use this online converter to convert between several hundred units (including metric, British and American) in 76 categories, or several thousand pairs including acceleration, area, electrical, energy, force, length, light, mass, mass flow, density, specific volume, power, pressure, stress, temperature, time, torque, velocity, viscosity, volume and capacity, volume flow, and more.
Note: Integers (numbers without a decimal period or exponent notation) are considered accurate up to 15 digits and the maximum number of digits after the decimal point is 10.

In this calculator, E notation is used to represent numbers that are too small or too large. E notation is an alternative format of the scientific notation a · 10^x. For example: 1,103,000 = 1.103 · 10⁶ = 1.103E+6. Here E (from exponent) represents “· 10^”, that is “times ten raised to the power of”. E-notation is commonly used in calculators and by scientists, mathematicians and engineers.

• Select the unit to convert from in the left box containing the list of units.
• Select the unit to convert to in the right box containing the list of units.
• Enter the value (for example, “15”) into the left From box.
• The result will appear in the Result box and in the To box.
• Alternatively, you can enter the value into the right To box and read the result of conversion in the From and Result boxes.

We work hard to ensure that the results presented by TranslatorsCafe.com converters and calculators are correct. However, we do not guarantee that our converters and calculators are free of errors. All of the content is provided “as is”, without warranty of any kind. Terms and Conditions.

If you have noticed an error in the text or calculations, or you need another converter, which you did not find here, please let us know!

TranslatorsCafe.com Unit Converter YouTube channel