The average principal salary at Mexia Isd was $70,083 , which is 32 percent lower than the average salary for this job in Texas, and 41 percent lower than the national average for this job . Principal salaries at Mexia Isd typically range from $65,500 to $75,500 (25th to 75th percentile). The highest reported principal salary was $76,760. There are 5 employees at Mexia Isd with the job title principal.