It took Meg Ryan less than a minute to fake it in When Harry Met Sally, but a new study has found that on average it takes women 13 minutes and 25 seconds to have a real orgasm.
In research that might have taken the passion out of the moment, women were asked to start a stopwatch when they became sexually aroused, and stop it again when they climaxed.
Around one in six of those who took part said they never climaxed during intercourse. Of the rest, the time it took ranged from 5 minutes 42 seconds to just over 21 minutes.
Almost nine in ten of those who took part in the research reported longer-lasting sensations when they were positioned on top.
Scientists who conducted the study between October 2017 and last September believe they are the first to measure "orgasmic latency" - the gap between arousal and climax.
A total of 645 straight women from 21 countries took part - a fifth of them from the UK - and all were married or in long-term relationships. The average age was 30, but writing in The Journal Of Sexual Medicine, the team from India's Kadave Institute of Medical Sciences said the age of women and how long they had been with their partner did not have a significant effect on how long orgasms took.
They defined the moment of becoming aroused as "an intense desire for sex in the presence of erotic stimuli, which were provided by the partner, audiovisual methods or both", and concluded that the average time to reach orgasm was 13 minutes and 25 seconds.
The study does, however, fail to mention a crucial fact: according to research from 2009, the average time for men to orgasm is just six minutes. Meanwhile, separate research at Geneva University found that female orgasm is accompanied by three to 15 involuntary contractions of the pelvic muscles and that the event lasts between three and 26 seconds.
Last year, another study found that men were also way off in estimating how often their wives orgasmed, with 43 per cent getting it wrong. That research, involving 1,683 newlywed couples, found than 87 per cent of husbands consistently experienced orgasm, but just 49 per cent of the women did.
Katz's Delicatessen, the New York restaurant where Meg Ryan and Billy Crystal filmed their famous scene, is holding a 'fake orgasm contest' in July to mark the film's 30th anniversary.