The pressure put on men to last longer in bed is epitomized in modern pop culture by rapper Missy Elliot who sings how she doesn’t want “no one-minute man,” and dancehall artist Ms. Thing who needs a “one-, two-, three-hour man.” Most men don’t want to finish first in the bedroom for fear of coming up short.

So, how many minutes of sex are enough, and how many are too few?

In an article for The Conversationalist, Dr. Brendan Zietsch, a psychologist from the University of Queensland, writes about what he has learned researching how long heterosexual couples report penetrative sex actually lasts.

Read: 5 Little-Known Things That Help Men Last Longer In Bed

He writes: "I know there’s a lot more to sex than putting the penis into the vagina and ejaculating, but the rest is not always easy to define (kissing? Rubbing? Grinding?). To keep things simple and specific, we’ll just focus on the time to ejaculation."

How do we define the beginning and end of sex? The definition is penis-centric. Zietsch measured the official time from penetration to ejaculation by observing data from 500 couples around the world who used a stopwatch to time their sex acts over a four-week period. Participants pressed "start" at the time of penile penetration and "stop" at ejaculation. A stopwatch was the preferred method of choice because people are more likely to be biased if simply asked how long they take without proper measure. Also, it’s a difficult measure since people don't normally stare at the clock while having sex.

Read: 4 Sex Myths That You've Had All Wrong

The findings revealed the average time for each couple, across all the times they had sex, ranged from 33 seconds to 44 minutes. Meanwhile, the average across all couples was 5.4 minutes. This means a couple will typically go for an average of 5.4 minutes every time they have sex.

Interestingly, condom use and circumcision did not affect duration in the bedroom. Some men believe condoms make them lose an erection because it removes all the sensitivity and feeling. However, a 2015 study found heterosexual men aged 18 to 24, who cited condoms as a barrier to an erection, were more likely to be suffering from general erectile dysfunction whether or not they used a condom.

Meanwhile, the country of origin did not affect sex duration, unless the couples came from Turkey, which tended to be significantly shorter (3.7 minutes) than couples from other countries. A couple’s age did influence how long sex lasts, with the older the couple, the shorter the sex.

Depending on what side of the sex duration spectrum men fall on, an average of five minutes could be good or bad. But, according to a 2008 study of United States and Canadian sex therapists, sex that is “too short” lasts one to two minutes, “adequate” lasts three to seven minutes, and “desirable” is seven to 13 minutes. The range for “too long” went from 10 to 30 minutes.

It seems that anything longer than ten minutes is ideal, but unusual.

So, why do we last as long as we do? Whether it’s two minutes or 30?

Zietsch suspects penis shape could affect sex duration in bed. In a 2003 study, using artificial vaginas, artificial penises, and artificial sperm (corn syrup), researchers found the ridge around the head of the penis is able to scoop out pre-existing syrup from the vagina. In other words, the repeated thrusting men do during sex could function to displace other men’s semen, before they ejaculate. This ensures their swimmers will have a better chance at reaching the egg first for fertilization.

“Incidentally, this could explain why it becomes painful for a man to continue thrusting after ejaculating, since that would risk scooping out his own semen as well,” writes Zietsch.

So, how long does sex really last? Clearly there’s no “normal” definition.

When it comes to the heat of the moment, pleasure has no number.