Research · Private high schools · October 2026
The largest private high school in 45 states, by grade 9-12 enrollment
As of October 2026: Pinkerton Academy in Derry, New Hampshire is the largest school on this list, with 3,074 students. St Francis Prep in New York is next at 2,420, and St Thomas Aquinas High School in Florida third at 2,045.
The table names the largest grade 9-12 private school in 45 states, each with at least 200 students. Six states have no school that meets that floor, so a state's best known private school may not be here.
Analysis: Test Prep Gurus (High School Reach, highschoolreach.com), October 2026. Figures and the table may be quoted with attribution to Test Prep Gurus.
The findings, in plain English
Catholic schools hold most of these spots. In state after state the largest private high school is Catholic: Mcgill-Toolen Catholic High School in Alabama at 856, St Pius X Catholic High School in Georgia at 1,096, Dowling Catholic High School in Iowa at 1,389 and Marquette University High School in Wisconsin at 893. Boarding schools lead in only a few states, among them Choate Rosemary Hall in Connecticut at 868 and Phillips Academy in Massachusetts at 1,187.
The spread between states is still wide. New Hampshire's entry enrolls 3,074 students. Montana's enrolls 298, the smallest number on this table. A state's largest private high school can still be smaller than a single grade at the public high school down the road.
The list counts only schools that begin at grade 9 and enroll at least 200 students. A private school that runs from kindergarten through grade 12, or from grade 6 up, is left out so the figure is a high school and not a whole-school total. A state is left off the table when its largest qualifying school has fewer than 200 students. That is why Alaska, Hawaii, South Carolina, South Dakota, West Virginia and Wyoming are not listed: the largest such school there has under 200 students.
The largest private high school in 45 states
One school per state, in state order, for the 45 states with a qualifying school of 200 or more students. Each school name links to its page.
Enrollment is the school's total in the federal Private School Universe Survey for 2021-22, limited to private schools whose lowest grade is 9 so the figure is a high school. Schools that also teach younger grades, including K-12 and 6-12 schools, are left out, which is why a state's best known private school may be missing. A state is left off this table when its largest qualifying school has fewer than 200 students. Alaska, Hawaii, South Carolina, South Dakota, West Virginia and Wyoming are not listed: the largest such school there has under 200 students. The survey is voluntary, so these counts are a floor among respondents.
Why the biggest private school you know may be missing
Most private schools in the United States teach more than four grades. A private school that runs from kindergarten through grade 12, or from grade 6 up, is left out so the figure is a high school and not a whole-school total. This list uses only schools whose lowest grade is 9.
The federal private school survey is voluntary. A school that did not answer has no row and cannot appear, so these counts are a floor rather than a complete census. This table also drops any state whose largest qualifying school has under 200 students, which removes six states from the list.
What the enrollment number covers
The figure is total enrollment at the school, as reported for 2021-22. Because every school here starts at grade 9, that total is the high school. A school's own site may show a newer and slightly different number, and the gap is usually small.
What a family should do with this
Use this as a starting list, not a shortlist. Size tells you something about course selection, sports and how many students share a counselor, and nothing about fit. A school of 1,810 and a school of 432 are different experiences, and either one can be right.
Then look for the school's own published college list. Many private schools print where their graduates enrolled, and Reach shows that list on the school's page when the school publishes it. That is the closest thing to an outcome a family can read before applying.
Questions parents ask
What is the largest private high school in the country?
Pinkerton Academy in Derry, New Hampshire is the largest school on this list, with 3,074 students.
Why are some states missing from this list?
A state is left off the table when its largest qualifying school has fewer than 200 students.
Are these private school counts complete?
The federal private school survey is voluntary. A school that did not answer has no row and cannot appear, so these counts are a floor rather than a complete census.
Method & sources: Enrollment is the school total in the federal Private School Universe Survey for 2021-22, limited to private schools whose lowest grade is 9 so the figure describes a high school rather than a whole school. Schools that also teach younger grades, including K-12 and 6-12 schools, are excluded, as are virtual schools. A state is included only when its largest qualifying school enrolls at least 200 students; Alaska, Hawaii, South Carolina, South Dakota, West Virginia and Wyoming do not meet that floor and are not listed. The survey covers respondents only and is voluntary, so these counts are a floor. One school is listed per state, the largest that qualifies.
This brief as data: /research/largest-private-high-school-in-each-state.json. Free for editorial use with attribution to Test Prep Gurus (High School Reach).
Related: High School Explorer · All rankings and leaderboards · The largest public high schools in America · How many high schools are in each state