How many chromosomes do sperm cells and egg cells have?

In sperm cell and egg cell contain half number of chromosome so that's why sperm cell and egg cell are known as haploid cell i. e. 1n. Haploid cells only found in meiosis (sex cells).

For example, in human beings the number of chromosome in sperm cell is 23 and also 23 in egg cell. When the sperm cell combine with egg cell, diploid cell is formed i. e. 2n. In diploid cells the number of chromosome is double.

23 chromosomes

Explanation:

A human body all together has 46 chromosomes but sperm and egg cells are gametes, or sex cells meaning each half of a parent created 46 all togehter. They are haploid cells while everything else are diploid.