---
tag: 0HVX863SAJ
kind: concept
name: Eccentricity
msc: [51N20]
sources:
  - url: https://en.wikipedia.org/wiki/Eccentricity_(mathematics)
    locator: lead section
same_as:
  wikidata: Q104486
  wikipedia: Eccentricity (mathematics)
---

## Summary

The eccentricity of a conic section is a non-negative real number that measures how far the conic is from a circle. It is $0$ for a circle, between $0$ and $1$ for an ellipse, $1$ for a parabola and greater than $1$ for a hyperbola.