Sienna Miller has a "bit of a sweater obsession" and she loves to wear a good quality jumper everyday.

Sienna Miller

Sienna Miller

The 37-year-old actress admits her regular wardrobe is very different to her red carpet looks and she is at her most comfortable in a jumper and pair of jeans each day.

However, she admits her penchant for sweaters is getting out of hand as she is running out of room in her wardrobe for her favourite type of garment.

In an interview with Vogue Australia, she said: "I pretty much wear jeans and a jumper every single day. Or wide-legged trousers and a sweater. I've got a bit of a sweater obsession. I'm really into them. And shoes ... whatever is on my feet is probably the most exciting part of whatever is my uniform. I can't stop, all I want is sweaters."

Sienna never relies on a stylist for her regular outfits but she does appreciate the help of celebrity stylist Kate Young - who also works with the likes of Margot Robbie and Dakota Johnson - when she is in work mode and is attending premieres to promote her films.

The '21 Bridges' star has one rule though, she has to feel comfortable when she is on the red carpet in front of the cameras.

Sienna said: "When I'm on a press tour, I'll work with Kate Young. What she will do is call in a load of dresses from designers I like, and then try on what I love.

"I just try to find something that feels right. And occasionally I get it wrong ... it depends. I don't use a stylist for my everyday life and I don't use a stylist for every red carpet event, but it helps having people sift through and pull (looks)."

When Sienna first became famous in the early 2000s she became known for her trademark boho look, comprised of gypsy skirts, floral dresses and fringed jackets.

Although the 'American Sniper' actress looks back on her hippy chic phase with a smile, she admits she did make a few fashion faux pas and is still shocked that she became a poster girl for boho.

Sienna said: "I mean, if I look back on the early '00s which is when it happened, I don't know that I'd put all of my clothes together in that way now, like I did then. It was a real moment in time and kind of amazing for people to respond in the way that they did, out of nowhere. I have always been drawn to that aesthetic.

"I look back and laugh at a lot of it now ... it doesn't bother me. It was a moment in time but I've evolved, is what I would say."