Public vs Private Schools by the Numbers

Scale: The Basic Numbers

The scale difference between public and private education is the first thing the data makes clear:

Public schools are, on average, 2.5 times larger than private schools. This affects nearly every comparison, larger schools can offer more programs (AP courses, extracurriculars, special education services) but may have less individual attention per student.

Class Sizes and Teacher Ratios

The student-teacher ratio is one of the most commonly cited differences. At ~16:1, public schools average four more students per teacher than private schools at ~12:1. However, several caveats apply:

• Ratio is not class size. The student-teacher ratio includes all teaching staff, including specialists, reading interventionists, and special education teachers who work with small groups. Actual classroom sizes are typically 20-28 students in public schools and 15-22 in private schools.
• Variation within sectors is enormous. Many public schools have ratios under 12:1 (especially well-funded suburban districts), while some private schools exceed 18:1. On PlainSchools, you can search individual schools to see their actual ratios.
• Special education staffing skews public ratios. Public schools must provide specialized instruction for students with disabilities (roughly 14% of public school students). These services require additional staff who lower the overall ratio but do not reduce regular classroom sizes.

Browse student-teacher ratios for public schools in your area using our best schools rankings or school search.

Teacher Qualifications

This is an area where public schools often have an advantage in the data. NCES reports that:

• Nearly all public school teachers (95%+) hold at least a bachelor's degree and state certification or licensure.
• About 57% of public school teachers hold a master's degree or higher.
• Private school teacher certification requirements vary by state and school type. Many private schools do not require state certification, though most teachers still hold bachelor's degrees.
• Public school teachers have higher average salaries ($65,000+) than private school teachers (~$45,000), which affects recruitment and retention.

Whether certification translates to better teaching is debated. Certification ensures minimum content knowledge and pedagogical training, but some argue that subject matter expertise and classroom skill matter more than credentialing. The data shows that public schools have a more formally qualified workforce.

Demographics and Diversity

Public and private schools serve substantially different student populations:

• Income: About 52% of public school students qualify for free or reduced-price lunch (an indicator of low family income). In private schools, this figure is much lower, many private schools do not participate in the federal lunch program at all.
• Ethnic diversity: Public schools are more demographically diverse than the U.S. population as a whole. Private schools, particularly nonsectarian independent schools, tend to be less diverse, though Catholic schools in urban areas are often highly diverse.
• Special education: About 14% of public school students receive special education services under IDEA. Private schools serve a much smaller share of students with disabilities, partly because they are not required to provide the same level of services.
• English learners: About 10% of public school students are English learners. Private schools serve a negligible share of EL students.

These demographic differences are critical context for any performance comparison. Public schools must serve every student in their attendance zone, including those with the most intensive needs. Private schools select their students (or are selected by families who can afford tuition), creating a fundamentally different comparison group.

Do private schools outperform public schools?

Raw test score comparisons consistently show private school students outperforming public school students. However, this comparison is misleading without demographic controls.

NAEP data shows that private school students score 10-20 points higher than public school students on average. But when researchers control for family income, parental education, and other demographic factors, the gap narrows dramatically, and in some studies, disappears entirely or reverses.

A landmark 2006 NCES study found that after controlling for student and school characteristics, public school students performed comparably to or better than private school students in mathematics. More recent analyses have reached similar conclusions: the apparent private school advantage is largely a demographic selection effect, not a school effectiveness effect.

This does not mean private schools are ineffective, it means the families who choose private schools tend to have characteristics (higher income, higher education, more educational involvement) that predict higher student achievement regardless of school type.

Spending and Funding

Funding comparisons between public and private schools are complex:

• Public school per-pupil expenditure: Averages about $15,000 nationally, funded by a mix of local property taxes (~45%), state funding (~45%), and federal sources (~10%). Ranges from under $10,000 to over $25,000 depending on state and district.
• Private school tuition: Averages about $12,000, but varies enormously. Catholic schools average $6,000-$8,000. Nonsectarian independent schools in major metros often charge $25,000-$40,000+.
• Hidden costs: Public school expenditure includes transportation, food service, and extensive special education, services that private schools often do not provide. Comparing per-pupil spending directly overstates the instructional spending difference.

Explore per-pupil spending by district on PlainSchools using our highest spending district rankings or district search.

The Bottom Line

The data does not support a simple conclusion that one sector is "better" than the other. Public schools serve a broader population, employ more credentialed teachers, and spend more per student when all services are included. Private schools offer smaller average class sizes and more selective environments. Academic performance differences between sectors are largely explained by student demographics, not school quality.

For families evaluating specific schools, the most useful approach is comparing individual schools on concrete metrics, student-teacher ratio, available programs, attendance rates, and community fit, rather than relying on the public/private label. PlainSchools provides these metrics for every public school; for private schools, contact the school directly or check your state's private school directory.

Frequently Asked Questions

How many public vs private schools are there in the US?

About 98,000 public schools serve ~49.4 million students, and ~30,000 private schools serve ~5.7 million students. Public schools educate about 90% of all K-12 students.

Are private school class sizes actually smaller?

On average, yes, private schools average ~12:1 student-teacher ratios vs ~16:1 for public schools. But variation within each sector is large. Some public schools have ratios under 10:1, while some private schools exceed 20:1. The ratio also includes specialists, so actual class sizes are higher in both cases.

Do private school students perform better on tests?

Raw scores are higher, but the difference largely disappears when controlling for family income and parental education. NCES research shows that public and private school students perform similarly when demographic factors are accounted for. The apparent advantage reflects who attends private schools, not the schools themselves.

How much does private school cost compared to public school?

Private school tuition averages ~$12,000/year (Catholic: $6,000-$8,000; independent: $25,000-$40,000+). Public schools spend ~$15,000/pupil from taxes, including services private schools often do not provide (transportation, special education, food service).

Does PlainSchools include private school data?

PlainSchools currently covers public schools using NCES Common Core of Data (CCD). Private school data comes from the separate Private School Universe Survey (PSS), which has more limited coverage. We may add private school data in future updates.