Researchers discovered women feel most confident and happy with their love life and body shape shortly before they reach 30.
It is also the period in their life when they enjoy the best sex – but the happiness is relatively shortlived.
Because by the time they have turned 30 they start worrying about growing old and developing grey hair and wrinkles.
A spokesman for home hair colour brand Clairol Perfect 10, which carried out the study of 4,000 women, said: “Everything in life hits its peak at some point, and nearly reaching your thirties isn’t so bad now.
“The age of 28 has been pinpointed as the time in a woman’s life their hair looks the best, body shape is at its peak and confidence is at an all-time high.
“The security of your job, having a steady income, being in a relationship and having strong friendships all help create the perfect point in our lives when everything comes together.
“Reaching and surpassing your twenties no longer triggers the downward spiral of your looks and self-confidence.
“And a little time put aside in hectic schedules for self-pampering and the odd beauty product can help keep you feeling young and looking your best.”
The survey of 25-65 year olds recorded the age at which women were most content in 12 key areas of their life.
According to the results, women are happiest in their career at 29 and most content with their relationships one year later at 30, despite having the best sex at 28.
But all is not lost for the over 30s, as women feel most content with their financial situation at 33 and at ease with their home and family life at 32.
The research found two thirds of women feel they age more quickly than men, and the women polled rated their appearance a measly five out of 10.
It also emerged that 56 per cent of women worry about losing their looks as they get older
But drinking from the fountain of youth doesn’t come cheap as the average woman will spend £600 every year, or more than Â£49 a month, on beauty products in a bid to stay looking young.
The research also found women spend over five days a year on their beauty routine – an average of 22 minutes every day.
Psychologist Corinne Sweet added: “Having a good hair day is essential to success both at work and in love, as many women still feel their hair is their crowning glory
“Considering it was found that women have six bad hair days a month, anything women can rely on to improve their hair at home, in the minimum of time with guaranteed results can mean a huge lift in well-being, confidence and self-esteem.
“This can help women feel they are in the driving seat in their lives, despite the challenging times of modern life and always being on the go.”