The life span of sperm after ejaculation depends on the circumstances.
Sperm ejaculated into a woman's vagina can live in a woman's cervical mucus or upper genital tract for three to five days. Fertilization is possible as long as the sperm remain alive. Sperm ejaculated outside the body might survive in semen — the fluid released during ejaculation — up to a few hours.
Sperm can be preserved for weeks when semen is stored at a lowered temperature — or years when semen is frozen.