How your running bra should fit — and everything else you need to know.

Do you have questions about running bras? We’ve got answers. Check out our fit tips, measuring guide, and 4 myths that have been debunked.

The Fundamentals of Fit

1) Check the Bottom Band

Check the bottom band

Make sure the bottom band of your running bra is snug and lies flat across your back — not riding up or loose around your rib cage.

2) Check the Cups

Check the Cups

The cups of your running bra should fit smoothly — spilling out the sides or front means the cup size is too small, while extra space means the cups are too big.

3) Check the Straps

Check the Straps

The straps of your running bra should lie smoothly against your skin, without sliding around or digging uncomfortably into your skin.

How to Measure Your Running Bra Size

You’ll need a flexible tape measure. It’s also best to wear a bra that doesn’t change your shape — no padding or compression. You can also just skip the bra.

Measure around your rib cage where the bottom band would sit. The tape measure should feel quite snug. If you get a fraction, round down to the nearest inch. Using the chart below, find your corresponding band size based on your measurement.

Band Measurement


Measure around the fullest part of your boobs — which may not be the center — and round up to the nearest inch. Then subtract your rib cage measurement. The difference in inches will determine your suggested cup size. If you get a fraction, round up to the larger size.

Cup Size Measurement

Four common fit myths

There is tons of advice out there about running bras, but not all of it is good. Thanks to biomechanical testing at the University of Portsmouth and almost a thousand runner interviews, here are four common fit myths that have been debunked.

Myth #1: Support preference for running varies a lot

Surprisingly, lab testing found that the amount of support women wanted for running fell within a fairly narrow range — even across a wide range of sizes.

Myth #2: Your exact measurements dictate your bra size

Although measurements provide a great starting point, you might feel most comfortable in a slightly different size. It all depends on preference. Start with measuring, but try on a size up or down if it doesn’t feel right.

Myth #3: It doesn’t matter if I wear an unsupportive bra

Research has shown that the lack of support can actually slow you down: women can lose up to 4cm of stride length due to poorly controlled breast movement. Over the length of a marathon, that’s an entire extra mile. It has been proven, a better bra can make you run faster!

Myth #4: Wearing two sports bras will offer better support

We wish all women would read this: if you are wearing a bra that fits properly and is specifically designed for running, you should never have to double up. It’s good to have a few different bras to rotate through the week, but the days of layering bras are long gone.

Click here to check out our great selection of running bras.