What Bra Size Is Sienna Miller?

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Sienna Miller is an American-British actress. She started her career as a model for Italian Vogue, Glamour, and Elle. She eventually rose to fame with her characters in Layer Cake, Alfie, and The Girl.

After years of tabloid scrutiny, people continue to find new things about her. In this article, I’m going to talk about Sienna Miller’s bra size and how determining the breast shape can help you find the right bra.

What Bra Size Is Sienna Miller?

Sienna Miller has a bra size of 32B. This suggests her bust measures around 33 to 34 inches. She must wear a bra with B cups and a band ranging from 28 to 30 inches.

Sienna Miller wearing a strapless dress with a floral design and a black jacket at a photoshoot

Aside from a slim body, Miller appears to have 32B east-west breasts, which means the boobs tend to be fuller at the bottom, and the nipples point outward. Former actress Alison Lohman also has a 32B bra size and Abbey Clancy also wears a 32B bra. The best bras for east-west breasts include push-up and plunge bras.

Like A cups, B cups can sometimes have gaping at the top. In such a case, Sienna Miller can use 30C or 34A to improve the fit. For context, fellow actress Natalie Portman wears a 34A bra.

Sienna Miller Measurements

Sienna Miller is average in height, measuring in at 5 feet 5 inches (5′ 5”). I estimate that her body measurements are 33-25-33 inches, which translates to a bust size of 34″, a waist size of 26″, and a hip size of 35”. She weighs roughly 119 pounds.

Benefits of a Small Chest

Don’t Have Back Pain

Ladies blessed with small breasts can avoid the dreaded back pain. Breast weight can cause your shoulders to move forward, which forces the muscles in your back and shoulder blades to adjust. Having less weight in front means your torso can easily carry your breasts, and the weight doesn’t need to be redistributed.

Button-Down Shirts Fit

Let’s face it – button-down shirts are not made for women with large breasts unless you plan on sizing up 1-2 shirt sizes. Women with A-B cups don’t have to experience this struggle, since their boobs are not busting out of these shirts. You can easily wear your normal shirt size without it feeling too tight on your chest.

Minimal Bounce During Workouts

One huge benefit of having small breasts is that they hardly affect athletic performance because of their lack of bounce. It can be painful to have your boobs bouncing around as you work out, and women with small chests don’t have to experience this pain. Plus, small boobs mean you can wear pretty much any sports bra style, even if it has minimal padding.

Drawbacks of a Small Chest

Breasts Stay Small as You Gain Weight

If your breasts are dense with tissue, they won’t grow in size even as you gain weight. In turn, they may look significantly smaller as you gain more fat in other parts of your body. However, if you lose weight, the fat in your breasts may also reduce, causing your boobs to become even smaller.

Don’t Always Fill Out Clothing

Despite its several benefits, among the most notable disadvantages of having small breasts is the chance that you won’t fill out bra cups or clothing. Particularly when the breast tissue is leaning toward the bottom, the shallow bustline can cause gaping cups.

Might Experience Breast Asymmetry

As you develop breasts, it’s normal for you to experience breast asymmetry. However, this can continue even as you reach adulthood, where the volume of one breast can be smaller than the other. There’s also the possibility that cleavage may veer toward the sides. When you are small chested, every ounce of boobage counts, so having asymmetrical breasts can be frustrating.

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Sienna Miller has a 32B bra size. This is a common bra size in America, so it’s easy to find the right styles, whether it’s a sports bra or a normal bra.


Allena is the Founder and Editor of The Better Fit, a platform dedicated to empowering women with practical advice on bras and fitness, inspired by her own revelation of the widespread issue of incorrect bra sizing. Her expertise and tips have been recognized by major publications such as Cosmopolitan, Better Homes & Gardens, Insider, and NBC, making her a trusted voice in women's wellness and lifestyle.