The U.S. school system runs on 13 grades, kindergarten through 12th, with optional pre-K before them and college or job training after. In the 2024-25 school year, 100,119 public schools in the 50 states and Washington, D.C., enrolled 49,070,752 students, according to allk12's analysis of the National Center for Education Statistics (NCES) Common Core of Data, the federal list of every public school.
States write the rules, local districts run the schools, and the federal government covers a minority of the cost while requiring yearly tests. NCES counted 13,318 regular public school districts in 2022-23. That count leaves out regional service agencies, state-run agencies, and charter schools that operate as their own districts. How the board, superintendent, and principal split the work is laid out in who runs your school district.
In fiscal year 2024, the 2023-24 school year, public schools took in $1.04 trillion, according to NCES. State governments supplied $475.7 billion and local sources $441.3 billion. The federal share was $121.2 billion, or 11.7%, and $42.0 billion of that federal money was COVID-19 relief funding.
Each state also sets its own attendance law. The Education Commission of the States (ECS) found in its 2025 review that 28 states require children to start school at 6, 11 states and D.C. at 5, 10 states at 7, and Washington state at 8. The requirement ends at 18 in 25 states and D.C., at 16 in 15 states, at 17 in nine states, and at 19 in Texas. That counts Kentucky at 18: ECS lists it at 16, the base age in its law, but every Kentucky district had to enforce 18 by the 2017-18 school year. Depending on the state, ECS wrote, "students are required to attend school for as few as nine years and up to 13 years." Every state's ages are in our compulsory attendance guide.
Charter schools are publicly funded but run independently of a traditional district. They made up 8,214 of the 100,119 public schools in 2024-25 and enrolled 3,950,158 students, about 8% of all public school students, according to allk12's analysis. More on how they work is in what a charter school is.
Outside the public system, 4.7 million K-12 students, or 9% of combined public and private enrollment, attended private schools in fall 2021, the latest year in NCES published tables. A newer NCES survey counted 30,553 private schools with 5,096,365 students in 2023-24. In the 2022-23 school year, parents reported that about 3.4% of students were homeschooled, according to the NCES 2023 National Household Education Surveys. Counting students in full-time virtual programs as well, 5.2% of children ages 5 to 17 received their instruction at home.
Levels, grades, and typical ages
Pre-K, short for prekindergarten, comes first and is optional, since no state's compulsory attendance age starts below 5. In 2024-25, 33,034 public schools offered pre-K and enrolled 1,366,790 pre-K students. Which states open pre-K to every 4-year-old is covered in our universal pre-K list. Elementary, middle, and high school then make up K-12.
| Level | Usual grades | Typical age at start of year | Public schools | Students | Share of students |
|---|---|---|---|---|---|
| Elementary | K-5 (also K-6, K-8) | 5 to 10 | 55,408 | 22,895,879 | 46.7% |
| Middle | 6-8 (also 7-8, 5-8) | 11 to 13 | 16,148 | 8,903,511 | 18.1% |
| High | 9-12 (also 7-12, 6-12) | 14 to 17 | 24,086 | 15,347,023 | 31.3% |
| Other or combined | K-12 and other mixes | Varies | 4,477 | 1,924,339 | 3.9% |
| Total | 100,119 | 49,070,752 | 100% |
Operating public schools in the 50 states and D.C., 2024-25, by NCES school level. Students include pre-K. Ages assume a child starts kindergarten at 5 and moves up one grade a year. Source: allk12 analysis of NCES Common Core of Data.
In 47 of the 51 jurisdictions (the 50 states and D.C.), the law entitles children to free public schooling from age 5, according to the ECS review. A child who starts kindergarten at 5 starts 12th grade at 17. Each state's birthday cutoff is in kindergarten cutoff dates by state, and the grade-by-grade chart is in what grade is my child in.
The grade spans vary more than the labels suggest. Of the 55,408 elementary schools, 27,067 (48.9%) run from pre-K, kindergarten, or 1st grade through 5th grade, 8,070 through 6th, and 7,360 through 8th, the K-8 model. Among middle schools, 10,790 of 16,148 (66.8%) teach grades 6 to 8, and 1,945 cover only 7th and 8th. Most high schools, 16,496 of 24,086 (68.5%), are four-year 9-12 schools, and they enroll 84.1% of high school students. Another 3,977 schools serve every grade from pre-K, kindergarten, or 1st grade through 12th. State-by-state school counts are in how many public schools are in the U.S.
After 12th grade comes postsecondary education. In 2021-22, NCES counted 3,542 degree-granting postsecondary institutions with first-year undergraduates: 2,267 four-year institutions and 1,275 two-year institutions.
Core subjects students take
Federal law sets the floor. The Every Student Succeeds Act requires states to test math and reading or language arts in each of grades 3 through 8 and at least once in grades 9 through 12. Science must be tested at least once in grades 3 to 5, once in grades 6 to 9, and once in grades 10 to 12. States add their own required courses and credit totals, which are compared in high school graduation requirements by state.
The NCES High School Transcript Study reads actual student transcripts. Its 2019 edition found that public high school graduates that year earned an average of 28.0 Carnegie units, the standard credit, which NCES defines as one credit for a yearlong course.
| Subject | Average credits, 2019 graduates | Average credits, 1990 graduates |
|---|---|---|
| English language and literature | 4.5 | 4.1 |
| Mathematics | 4.2 | 3.2 |
| Social sciences and history | 4.0 | 3.4 |
| Science (biology 1.4, chemistry 0.8, physics 0.4, other 1.1 in 2019) | 3.7 | 2.8 |
| Career and technical education | 3.4 | 4.0 |
| Visual and performing arts | 2.3 | 1.6 |
| World languages | 2.1 | 1.5 |
| Other courses | 3.8 | 3.0 |
| Total | 28.0 | 23.5 |
Average Carnegie units earned by public high school graduates. Source: NCES Digest of Education Statistics, Table 225.10, from the High School Transcript Study. Details may not add to totals because of rounding.
On average, 2019 graduates took more than four years each of English and math, four of social studies and history, and close to four of science. Biology averaged 1.4 credits, more than chemistry and physics combined (0.8 plus 0.4 equals 1.2).
Graduates in 2019 earned 4.5 more credits than those in 1990 (28.0 minus 23.5). Math rose by a full credit, from 3.2 to 4.2, and science rose from 2.8 to 3.7. Career and technical education was the one subject that fell, from 4.0 credits to 3.4.
Sources
NCES: Digest Table 214.10, Number of public school districts and public and private schools
NCES: Revenues and Expenditures for Public Elementary and Secondary Education, Fiscal Year 2024
Education Commission of the States: Free and Compulsory School Age Requirements 2025
NCES Condition of Education: Private School Enrollment
NCES: Characteristics of Private Schools in the United States, 2023-24 Private School Universe Survey
NCES/IES: A Higher Percentage of K-12 Students Are Receiving Academic Instruction at Home
NCES Condition of Education: Characteristics of Degree-Granting Postsecondary Institutions
Cornell Legal Information Institute: 20 U.S. Code 6311, State plans (Every Student Succeeds Act)
NCES: Digest Table 225.10, Average Carnegie units earned by public high school graduates
School counts, enrollment, grade spans, charter, and pre-K figures from allk12's analysis of National Center for Education Statistics (NCES) Common Core of Data, 2024-25.
