The transcendence degree of , sometimes called the transcendental degree, is one because it is generated by one extra element. In contrast, (which is the same field) also has transcendence degree one because is algebraic over . In general, the transcendence degree of an extension field over a field is the smallest number elements of which are not algebraic over , but needed to generate . If the smallest set of transcendental elements needed to generate is infinite, then the transcendence degree is the cardinal number of that set.

For instance, the transcendence degree of over is one. The transcendence degree of over is an infinite cardinal number. There are many open questions about the traditional constants in mathematics, such as the transcendence degree of .