After font size is determined from the X dimension requirement, now it is time to find which font meets the bar height requirement. In this pack seven different bar heights at any given font size. At 12 points, the barcodes produced will have the following heights:
Table 3.2. Bar Heights of Code39 Fonts (at 12 points)
| Height Option | Bar Height (inch) | Bar Height (cm) |
|---|---|---|
| XXS | 0.125 inch | 0.318 cm |
| XS | 0.250 inch | 0.635 cm |
| S | 0.375 inch | 0.952 cm |
| M | 0.5 inch | 1.27 cm |
| T | 0.625 inch | 1.588 cm |
| XT | 0.750 inch | 1.90 cm |
| XXT | 1.0 inch | 2.54 cm |
Assume that you need a font to produce barcodes with X dimension at 15 mils and bar height at 1 inch. From the X dimension table 18 points should be used as the font size. At 18 points, T fonts produce bar height of 0.625X18/12=0.94 inch, whereas XT fonts produce bar height 0.75*18/12=1.125inch. Both are closest matches to the requirement. If requirement says that the bar height must be at least 1 inch, then XT fonts should be selected.