Loop on the side of your bra: what is it for?

That little loop on the side of your bra cup is there for a reason: your strap runs through it before heading back to the band, so it stays put on your shoulder instead of sliding toward your neck or your arm. At the same time, it pulls the side of your cup in against your body, so your breast doesn't spill over the edge there. Not every bra has this loop. It depends on the style and how the side panel is sewn, so if yours doesn't have one, nothing is necessarily wrong with it.

How does this little loop actually work?

Take a look at the inside of your bra, right at the seam where the cup meets the side panel. On some styles, there's a small piece of elastic or fabric sewn in there, with an opening the strap threads through before continuing on to the band. That's the loop we're talking about.

By anchoring the strap at that point, it pulls in two directions at once: up toward your shoulder, and sideways toward your body. Without that loop, a strap only pulls straight up, and you feel that difference right away in how the bra sits, especially with a fuller cup.

1. It guides your strap to the right spot on your shoulder

A strap that's only attached to the front and back of the cup tends to slide outward on its own, toward your arm, where it can dig in or keep slipping off. The loop on the side keeps the strap in place, closer to your neck, which is really where it belongs.

Try this: pull your strap partway off your shoulder and let go. Does it snap right back toward the outer edge of your shoulder, toward your upper arm? Your bra is probably missing something that guides the strap, like this loop.

2. It keeps the side of your cup against your body

This might be the most important job it does. Because the strap runs back through the side panel instead of going straight from the cup, it pulls the side of your bra more firmly against your rib cage. That keeps your breast from spilling over the edge, or both cups from pushing toward each other into one shape in the middle. You know the look: uniboob.

"I can only see on the videos that there's a loop on the sides where you thread the strap through, and mine doesn't have that. I think it would fit better if it did."

This shopper spotted the difference right away in the product photos. She's right: without that loop, the side panel is missing just the bit of extra grip that keeps your breast from shifting outward.

Try this: stand in front of a mirror in your bra and lean forward slightly, like you're picking something up. Does your breast spill over the side of the cup, near your arm? Then the side panel of your bra isn't firm enough, loop or no loop.

3. It spreads out the weight, so the strap doesn't dig into your shoulder

Of the nearly 2,900 women we asked about their biggest bra complaint, almost one in ten (9.6%) named the straps as the main problem. Usually it's straps that dig in, twist, or keep slipping down. A strap anchored at two points instead of one spreads the weight of your breasts across your shoulder and the side panel together, instead of putting it all on one narrow strip of fabric.

That matters most with a fuller cup, where a narrow strap ends up carrying the whole load on its own. A wider band helps too: it takes weight off your shoulders instead of leaving your straps to handle everything by themselves.

Try this: push a finger under your strap on your shoulder. Do you feel a clear groove, or a red mark that doesn't fade within a few minutes? Your strap is carrying too much weight alone, and a second anchor point like this loop would make a difference.

Why doesn't every bra have this loop?

The loop is a design choice, not a mark of quality. Some bras are sewn so the side panel of the cup is already firm enough on its own, thanks to a double layer of fabric or extra-high side panels that hold the cup in place without the strap needing to pull on it there. Other styles use that loop to get the same effect with thinner fabric.

That's why you can lay two bras from the same brand side by side, one with a loop and one without, and both fit just fine. So it's not a sign that something is missing from your particular bra, unless it was clearly visible in the product photo and yours has a loose thread or a hole where something should be.

Your bra is missing the loop you saw in the photo: now what?

First check whether something's actually missing, or if it's just a different design. Lay your bra flat and look at the inside of the side panel near the cup. Do you see a clean, finished seam with no opening? Then that's simply how this style is made. Do you see a loose thread, a hole in the fabric, or a piece of elastic hanging loose? Then something did go wrong in the finishing.

• No loop at all, and the bra fits loose or shifts to the side: this style was probably designed without one, so the support has to come from the side panel itself.
• A loose thread or hole where something was clearly supposed to be: that points to a finishing defect. Contact customer service.
• The strap keeps popping off or shifting while you wear it: that usually points to the wrong size rather than a missing loop.

Not sure if your bra fits right, loop or no loop? Check out our article on straps that keep slipping off in the back, which has more self-checks to help pin down the cause.

Does this actually have anything to do with your bra size?

Sometimes a missing loop looks like the culprit when it's really a sizing issue. Say you're wearing a 36C and your breast still spills over the side: try going up a cup size in the same band, so a 36D. A cup that's too small will always push outward, loop or no loop.

The Daily Essential Bra size chart runs from a B cup through an H cup, with bands from 32 to 48, across 12 sizes from S to 3XL+. If you're not sure about your size, start by remeasuring your band and cup with our guide to measuring your bra size, so you know whether the problem is the size or the design.

Looking for a bra that actually holds the side in place?

If spilling over the side or a strap that keeps shifting is your biggest complaint, don't just look for that one loop. Look at the whole side panel of the cup. Our Daily Essential Bra uses a double layer of molded fabric that holds everything in place along the side, specifically to prevent spilling and uniboob, plus straps you can adjust yourself. The memory foam cups mold to your own shape, instead of you having to adjust to the cup.

That combination keeps the side panel exactly where it should be, without needing to rely on one loose loop. And if the fit still isn't right, you've got the 30-day perfect fit guarantee to fall back on.