Dimensions Of Letters

• The Nominal Size of lettering is defined by the height (h) of the outline contour of the upper-case (capital).
• Central Line is the imaginary line in the middle of each line or line element which is a constitutive part of a graphic character set.
• If we consider d as the width of the line element and h as the height of the line element, then the two standard ratios for d/h are: 1/14 and 1/10, which are feasible because they result in a minimum number of line thicknesses.
• Location of Central Lines- The nominal size (h) and the spacing between characters (a) shall be taken as the basis for defining the central line.
• Range of Nominal Sizes -The range of nominal sizes are 2.5 mm ;3.5mm ; 5 mm; 7 mm; 10 mm; 14 mm; 20 mm;
• The multiple of 1.414(square root of 2) is the range of heights for lettering is derived from the standardized progression of dimensions for paper sizes.
• Lettering Angle-The lettering may be vertical (upright) or inclined (sloped) to the right at 75° from the horizontal.
• The spacing between two characters may be reduced by half, if this gives a better visual effect.
• various letters are divided into no. of parts so that dimensions will be accurate.
  
• The size of letter is described by its height. According to the height of letters, they are classified as :

Lettering A

Characteristic	Parameter	Ratio	Dimensions(mm)
Lettering Height (Height of capitals)	h	(14/14)h	2.5	3.5	5	7	10	14	20
Height of lower case letters (without stem or tail)	c	(10/14)h	-	2.5	3.5	5	7	10	14
Spacing between characters	a	(2/14)h	0.35	0.5	0.7	1	1.4	2	2.8
Minimum spacing of base characters	b	(20/14)h	3.5	5	7	10	14	20	28
Minimum spacing between words	e	(6/14)h	1.05	1.5	2.1	3	4.2	6	8.4
Thickness of lines	d	(1/14)h	0.18	0.25	0.35	0.5	0.7	1	1.4

Lettering B

Characteristic	Parameter	Ratio	Dimensions(mm)
Lettering Height (Height of capitals)	h	(10/10)h	2.5	3.5	5	7	10	14	20
Height of lower case letters (without stem or tail)	c	(7/10)h	-	2.5	3.5	5	7	10	14
Spacing between characters	a	(2/10)h	0.5	0.7	1	1.4	2	2.8	4
Minimum spacing of base characters	b	(14/10)h	3.5	5	7	10	14	20	28
Minimum spacing between words	e	(6/10)h	1.5	2.1	3	4.2	6	8.4	12
Thickness of lines	d	(1/10)h	0.25	0.35	0.5	0.7	1	1.4	2