# What is word size 1

## Font size calculator

The calculation of the font size according to DIN 1450 refers to the middle length. The general rule is that the font size (here: middle length) is to be determined depending on the viewer distance. The closer the viewer is, the smaller the text to be read can be and vice versa. DIN 1450 uses the viewing angle to make a statement about the desired center length regardless of the viewer's distance. The viewing angle is the angle at which a viewed object is perceived. For the three types of text reading text, consultation text and signaling text, DIN 1450 specifies minimum values ​​for the mean length over the viewing angle in the unit Arc minutes expressed. See also the Wikipedia article on Apparent Size and Visual Acuity.

Based on the minimum values ​​specified in DIN 1450 for the specified viewing angle α can use calculations in the isosceles triangle to determine the mean length M. taking into account the viewer's distance D. be determined. The following applies:

In addition, DIN 1450 enables the visual acuity of the observer (visual acuity) and the adaptation luminance (simplified: illumination) of the sign carrier to be taken into account in the calculation. Both aspects are taken into account as a luminance / visual acuity correction factor KLV into the calculation as follows:

The luminance / visual acuity correction factor KLV can be derived from Table A.1 of DIN 1450 as follows:

This corresponds to LfV1 the luminance correction factors readable in line 1 at a visual acuity of 1. V corresponds to the visual acuity of the observer.

In almost every computer program you can only specify the font size (actually the height of the cone), but not the center length. In order to calculate a value for the font size from the calculated center length, the center length / font size ratio must be M.S. be known of the font used. This can vary greatly from font to font. It can be determined by measuring the center length with a known font size using the quotient of the center length M. and font size S. determine:

As long as no individually determined value is entered in the specified field, this font size calculator assumes a standard center length / font size ratio of 0.47, which can be derived from DIN 1450. The output of the recommended font size in points is only a rough value in this case. The calculation of the center length in millimeters, however, is always exact.

### Special features when calculating font sizes on the screen

Some special features apply to the calculation of font sizes for screen display (cf. digital media). Therefore, the virtual resolution of the device in pixels per inch (ppi) must be specified in an additional field.