Epson TM-T20III Technical Reference Manual page 81

Appendix
58 mm {2.28"} width paper printing
The maximum printable area of paper with a width of 57.5 ± 0.5 mm {2.26 ± 0.02"} is 52.6 ± 0.2 mm {2.07 ±
0.008"} (420 dots), and the approximate space is 3.0 mm {0.12"} on the left side and 2.0 mm {0.079"} on the right
side.
81