And they have the most sex when they are 25 – eight years after losing their virginity.
Men, meanwhile, wait until they are 33 before having their best sex – and have their most sex when they are 29.
The findings – in an exclusive poll of 1,281 people for Britain’s biggest online sex toy retailer lovehoney.co.uk – go against research which says that men reach their sexual peak at 18 and women at 30.
Lovehoney asked participants when they lost their virginity, at what age they had the most sex and at what age they had the best sex of their lives.
Men lost their virginity at 18 and women a year younger at 17.
Of those polled, 40% said their were having the best sex of their lives right now.
However, only 17 per cent of people said they were having the most sex of their lives right now.
For most people, the best sex of their lives did not happen when they were having the most.
On average, people had the best sex of their lives three and a half years later than the most sex of their lives.
The wait for great sex was longer for men at 15 years, while it took women 11 years to have the best sex of their lives after the first time.
The survey highlighted a shift towards losing virginity earlier.
The average age of virginity loss was 17 for those in their 20s, 30s, 40s and 50s, but those in their 60s waited until they were 18. On average, those aged under 20 were almost two years younger than those in their 60s when they lost their virginity - having sex for the first time when a few months shy of the legal age of 16.
People in their 50s and 60s who took part in the survey said they had their best sex when they were 46.
Sex and relationship expert Tracey Cox, who has her own range of sex toys with Lovehoney, said: “Like most things, sex gets better the more you do it and the more practised you are at it.
“So it makes sense for men to be having better sex at 33 rather than 18.
“It takes time to learn how to control their orgasms and to fathom the complex female sexual system.
“I suspect when they say ‘best sex’, a lot of men mean it’s when they felt most confident as lovers.
“This reinforces what we’ve always known: it’s not about quantity, it is about quality.
“We tend to have the most sex at the start of relationships when desire is fresh, and the best sex once we’re more in tune with our bodies and our partner.
“Hopefully, there are several periods in people’s lives that they could point to, not just one.
“Especially when lots of people have several long-term relationships in their lifetime.”
Tracey was not surprised that women had the best sex of lives younger than men.
She said: “This destroys the myth that it takes women longer to master their sexual responses.
“Despite the female sexual system being far more complex than a man’s, women are discovering what works and doesn’t faster than men. “I think it’s because there’s a lot more practical information out there for women to access and women read more books and actively look for answers or seek help if they’re having problems. Men don’t, which is probably why they take a little longer to truly feel they’ve reached a peak.”
As for when she had the best and most sex of her life, Tracey said: “I couldn’t reduce it to a single age because, happily, I’ve had many periods of my life when I’ve had great sex and lots of it. Hopefully this will continue and the best and most sex I’ll have is still in the future.”
Hollywood actress Cameron Diaz, 39, said she had enjoyed the best sex of her life in her 30s.
"The fountain of youth for me is exercise, healthy diet, lots of water, lots of laughter, lots of sex - yes, sex, we need that as human beings. It's healthy, it's natural, it's what we are here to do."
Lovehoney owner Neal Slateford said: “Although there is a definite peak for frequency of sex, quality of sex tends to be perceived to be best in a person’s present, or their recent past.
“It’s heartening to know that people are making the effort to keep sexual happiness and satisfaction on the agenda throughout their lifetime.
“This complex and fascinating topic is very subjective and working on averages simply can’t take into account the variety of relationship types and lengths that could impact on frequency and quality of sex.
“We also know that Lovehoney customers, who mostly own at least one sex toy, are twice as likely to say they’re satisfied with their sex life in the first place than non-sex toy owners.”