average age for a senior in high school
Report Abuse. The average age for seniors in highschool is 18. work it down from there. For college it is freshman 18 or 19 and 22 or 23 for college (university) senior in a four year college.Brian Â· 5 years ago.eport Abuse. Most kids start primary school (elementary) at around 5-6 years of age. From there it gets a little weird for middle school (jr. high), some place start it in the 6th year, others the 7th, then in high school, it starts at the 9th year, so freshmen are usually 13-14 years of age and graduate at 17 or 18.