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Teacher-Student Ratio

The number of students per full-time-equivalent teacher at a school, often used as a proxy for class size and resource allocation, though the two measures are not identical.

Reviewed by OpenSchoolData Editorial Team

How It Works

The teacher-student ratio divides total student enrollment by the number of full-time-equivalent (FTE) teachers. The national average is approximately 16:1, but this varies widely, from under 12:1 in some northeastern states to over 20:1 in parts of the West and South. Teacher-student ratio and class size are related but different concepts. The teacher-student ratio includes all teachers (including those not assigned to regular classrooms, such as specialists, reading interventionists, and special education teachers), while class size measures the actual number of students in a specific classroom. A school might have a 15:1 teacher-student ratio but class sizes of 25-28 because many teachers are serving in non-classroom roles. Research on the effect of class size on student outcomes is among the most studied topics in education. The Tennessee STAR experiment, one of the most rigorous education studies ever conducted, found that students in smaller classes (13-17 students) in kindergarten through third grade showed significant achievement gains, and these gains persisted into later grades. The benefits were largest for minority students and students from low-income families. On OpenSchoolData, teacher-student ratio is displayed on each school page from NCES CCD data, providing school-level context for understanding the school's resources and staffing.

Related Terms

  • Per-Pupil Spending, The total amount of money a school or district spends divided by the number of enrolled students, used to compare resource levels across schools and states.
  • School Data Profile, The collection of real federal data OpenSchoolData presents for each school, including NCES enrollment, demographics, student-teacher ratio, and EDFacts proficiency and graduation rates.
  • School Report Card, An annual public document produced by each state that provides performance data, demographic information, and accountability ratings for every public school and district.

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Real federal data: NCES CCD enrollment (2022), EDFacts proficiency rates (2020, district-level), EDFacts graduation rates (2019, district-level).

About This Definition

This definition is part of the OpenSchoolData Education Glossary, 33 terms explaining how school performance data works in the United States. All definitions are written in plain language for parents, educators, journalists, and researchers.

Teacher-Student Ratio is one of the U.S. K-12 school outcomes and enrollment concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the NCES Common Core of Data and EDFacts data behind every per-entity page on the site.

In the NCES Common Core of Data and EDFacts data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.

Source: NCES Common Core of Data, 2026.