The average woman will change dress size 31 times during the course of her adult life, according to new research.
Key size-gain spikes in life are having kids, moving in with a partner and the first years of marriage - while major size-drops occur pre-wedding, after the loss of someone close and following break-ups.
Regular 'blips' happen during Christmas and the winter period - and also after holidays away.
Men will typically go up or down a clothes size on 24 occasions as an adult - with a third identifying stress at work as the reason for the change.
The research of 1,000 women and 1,000 men was commissioned by Fits Me, a fit tool that helps shoppers to find their perfect size.
Stuart Simms, CEO at Fits Me said: "Getting clothes that fit can be very tricky at the best of times and changes in size aren't necessarily due to life events.
"However the results show that it is perfectly normal to go up and down clothes size, regardless of gender.
"Ultimately whether your clothes size changes or not, the important thing is feeling confident in yourself - and getting the fit right is a key part of this."
Six in 10 women said they aren't happy with their clothes size - compared to 45 per cent of men who feel the same way.
Three quarters of females own garments that no longer fit them properly with around 16 ill-fitting items found in the average woman's wardrobe.
While 61 per cent of males have kept hold of clothing that is either too big or too small for them - on average keeping hold of 14 items.
Half of respondents said they hang on to clothes that don't fit because they want to get back into them one day and a fifth have a sentimental connection to the items.
The typical female is most happy with her clothes size aged 28 and men are most content at 29 years old.
In contrast, women are most dissatisfied with their proportions at 38 while males feel similarly aged 39.
A quarter of men and almost half of women have avoided going to clothes shops because they were concerned they wouldn't find garments that fit as they would like.
Four in 10 respondents have been shopping for clothes only to find their size has gone up while 26 per cent have seen their size go down.
Perhaps as a result, three quarters of females and 44 per cent of males said they worry about finding something that will fit well.
While 21 per cent of men said they experience a drop in confidence when clothes shopping and two in five women said the same.
Over a fifth of Brits admit they aren't confident they know which clothing items look best on them - however three quarters said their size changes from retailer to retailer.
Of those surveyed, 58 per cent have felt intimidated by shops that are "too cool" - with the range of clothes available the thing that threatens them the most, followed by the prices and the shop staff.
Three quarters of respondents buy clothes online, however 86 per cent think it's a gamble as to whether the items ordered will fit as hoped.
Four in 10 people prefer to try clothes on in a shop fitting room and 45 per cent would rather be left alone to do so - and on average three items will be taken into the changing room with them.
A third of men and women would rather see how the garments look on them at home and 28 per cent have no preference.
The number one boost to people's confidence when clothes shopping is seeing clothes they like - followed by getting something that fits well and finding an item in the sale.