# Ovality

In telecommunications and fiber optics, **ovality** or **noncircularity** is the degree of deviation from perfect circularity of the cross section of the core or cladding of the fiber.

The cross-sections of the core and cladding are assumed to a first approximation to be elliptical. Quantitatively, the ovality of either the core or cladding is expressed as
, where *a* is the length of the major axis and *b* is the length of the minor axis. The dimensionless quantity so obtained may be multiplied by 100 to express ovality as a percentage. Alternatively, ovality of the core or cladding may be specified by a tolerance field consisting of two concentric circles, within which the cross section boundaries must lie.

In measurements, ovality is the amount of out-of-roundness of a hole or cylindrical part in the typical form of an oval.

## In chemistry

In computational chemistry, especially in QSAR[1] studies, ovality[2] refers to, a measure of how the shape of a molecule approaches a sphere (at one extreme) or a cigar shape (at the other). Ovality is described by a ratio of volume to area:

where:

- O = Ovality
- A = Area
- V = Volume

The ovality of the He atom is **1.0** and that of HC_{24}H (12 triple bonds) is **~1.7**.