A mailing label that measures 1" x 3.5" with a 1/8" margin on each side gives you a 3.25" printing area.

If you are printing in 12 characters per inch, you would set your form width at 39 (i.e., 3.25 x 12 = 39). If you are printing in 10 characters per inch, you would set your form width at 32 (i.e., 3.25 x 10 = 32.5). If you are printing in 16.7 characters per inch, you would set your form width at 54 (16.7 x 3.25 = 54.275).

If you are printing on mailing labels that are 1 x 4 inches, your printing area would be 3.75 inches if you allowed a 1/8" inch left and right margin. If you are printing in 12 characters per inch, you would set your form width at 45 (i.e., 3.75 x 12 = 45). If you are printing in 10 characters per inch, you would set your form width at 37 (i.e., 3.75 x 10 = 37.5). If you are printing in 16.7 characters per inch, you would set your form width at 62 (16.7 x 3.75 = 62.625).