The French luxury fashion house Hermes designed what became known as the Birkin bag in 1981.
But Birkin, 70, has told the BBC that if, like her, you fill the bag with "junk... and half the furniture from your house, it's a very, very heavy bag".
She said: "Now I fill my pockets like a man, because then you don't actually have to carry anything."
Birkin had met the chief executive of Hermes on a flight from Paris to London and told him she was struggling to find the perfect holdall.
He offered to design one and asked if the company could name it after her.
She said she was "flattered to death and said yes, yes, yes".  Suddenly everyone was "wandering around with your handbag", she added.
The holdall has become the ultimate status symbol. Hugely expensive - costing up to Â£100,000 - it has a long waiting list and is carried by the rich and famous.
Birkin said the bags have been "useful" over the years because she has sold them and donated the money to the charities she supports, including Amnesty International.
But the bag has also proved controversial.  In 2015 she asked Hermes to rename the crocodile Birkin bag after learning of disturbing practices in its production.
At the time, Hermes said it was looking into the allegations.
Birkin said it amused her that people still associate her with the bag, after a career spanning half a century.
She has appeared in more than 70 films, including Blow-Up and Death on the Nile, and made more than a dozen albums.
On her latest, Le Symphonique, she sings songs written by her former French lover Serge Gainsbourg - who died in 1991 - accompanied by a 90-piece orchestra.
But Birkin said she was in no doubt she would always be best known for her erotic record Je t'aime, moi non plus.
She recorded the breathy single with Gainsbourg in 1969. It was denounced by the Vatican, banned by the BBC and went on to top the charts.
"It's a rather extraordinary record," Birkin said. "Perhaps more interesting than the bag."
Le Symphonique is out in the UK on 7 April.
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Singer and actress Jane Birkin has said she now rarely uses the famous handbag that bears her name.