When a person ejaculates they release an average of 39 million sperm cells from their body. While some sperm will go on to fertilize an egg, most will die.
But, how quickly a sperm dies depends on the environment it's in. Whether in hot tubs or cryogenic chambers, here's how long sperm survive outside of the body.
How long sperm lives on skin
"While this depends on the health status and age of the person, a majority of sperm will die within 15 to 30 minutes on skin or surfaces," says Kimberly Langdon MD, an OB-GYN at the online medical service Medzino.
Regardless of the surface it is on, sperm is considered dead, and unable to lead to pregnancy, once semen — the ejaculated liquid holding the sperm — has dried.
Beyond health and age, temperature and moisture also determine the lifespan of ejaculated sperm, says Michael A. Witt, MD, a urologist and male fertility specialist at Reproductive Biology Associates. For example, sperm on a dry, cold bed sheet may die faster than sperm on a warmer surface like human skin.
Even though sperm can survive on the skin or outside the body for this short period, the chance of it fertilizing an egg and causing pregnancy is incredibly low, says Langdon. A person would have to touch the sperm and then their vagina before it dries, or the sperm would have to drip into the vagina for any chance of pregnancy.
How long sperm lives in the uterus
Sperm can survive within a person's reproductive system for up to five days after entering.
Immediately after moving into the vagina, semen forms a protective gel around sperm to shield them from the vagina's acidity. Within 30 minutes, the gel is liquefied as the sperm exits the vaginal canal and enters the cervix. This liquefaction allows sperm to move more freely through the cervical mucus, up through the uterus, and finally into the fallopian tubes.
The fastest swimming sperm may reach the fallopian tubes within minutes of ejaculation. However, pregnancy can only occur if an egg happens to pass through the fallopian tubes within the five days of the sperm's arrival. The chances of that are small unless you've timed it just right to have sex in the few days leading up to ovulation.
Most sperm will never reach the fallopian tubes, however. Instead, they will be removed from the vagina once a person engages in physical acts such as becoming upright, using the bathroom, or coughing, says Langdon.
How long sperm lives in a hot tub
Witt says sperm can only survive in a hot tub for a matter of seconds. Because the exceedingly steamy water and chemicals that make up a jacuzzi are toxic to sperm.
As for a warm bath, sperm may last up to a few minutes, says Langdon.
However, Witt explains getting pregnant from loose sperm in the water of a hot tub or warm bath is next to impossible. Because once the sperm is dispersed in the water, it is no longer protected by semen, and quickly dies.
However, if you have penetrative sex while in a hot tub or warm bath, pregnancy is far more likely to occur.
How long sperm lives while frozen
Sperm that has been collected by a doctor and frozen can live indefinitely under proper conditions.
A 2019 study published in Fertility and Sterility analyzed 119,558 semen samples from young adult men kept in cryostorage between six months and 15 years. The survival rate of previously frozen sperm decreased from 85% to 74% over that period. Sperm stored for 11 to 15 years had a live birth rate of 74% to 80%, compared to about 82% in sperm stored for six months to five years. Therefore, long-term freezing had minimal impact on the viability of sperm.
Witt says a person may want to freeze their sperm:
Another reason someone may choose to freeze their sperm is azoospermia — a condition in which there is no sperm in the semen due to blockage of the reproductive tract or hormonal changes. It affects about 1% of people and can make pregnancy through intercourse very difficult.
How long sperm can live outside the body depends on the environment, but once sperm is dried, it is no longer viable. On skin or other surfaces, sperm can live between 15 and 30 minutes.
In hot tubs or bath water, this lifespan decreases to a few seconds or minutes. However, freezing sperm can extend their lifespan indefinitely.