What is the maximum number of electrons an orbital may contain?

The maximum number of electrons an orbital may contain is 2 electrons.

Explanation:

There are 4 atomic orbitals called s, p, d and f.

There are one orbital s and it has 2 electrons.

There are three orbitals p, each one contain 2 electrons and in total they have 6 electrons.

There are five orbitals d, each one contain 2 electrons and in total they have 10 electrons.

And there are seven orbitals f, each one contain 2 electrons and the maximum number of electrons this orbital can contain is 14 electrons.