Run Happy Blog
Gear & Technology
How your running bra should fit — and everything else you want to know.
Questions about bras for running? We’ve got you covered. Check out our measuring guide, fit fundamentals, and extra tips to make sure your bra is ready to run.
How do I figure out my bra size in the first place?
Being fitted by a bra expert at a running store is probably the best option, but you can also measure your own size at home with just a few tools
Gather your tools, then get started.
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.
How do I measure my band size?
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. Use this chart to find your corresponding band size based on your measurement.
How do I figure out my cup size?
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 translates to the letter of your suggested cup size in this chart. If you get a fraction, round up to the nearest inch.
Once you know your size, remember these fit fundamentals.
Making sure your bra fits is the first step on the road to a great run. The best bra in the world won’t truly perform if it doesn’t fit correctly. But don’t worry! Our bra designers have some handy tips to help ensure you’re getting the best out of your bra.
How should the bottom band fit?
Make sure the bottom band is snug and lies flat across your back — not riding up or loose around your rib cage.
If the bra has built-in cups, how should they fit?
The cups 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. If your bra has removable cups, make sure they’re centered around your boobs and that they’re secure in the bra.
And if your bra doesn’t have cups at all, just ensure that the band isn’t pulling away from your rib cage — this can mean that the bra is too small for your cup size.
Should bra straps be super tight?
Straps should lie smoothly against your skin, without sliding around or digging uncomfortably into your skin.
Bonus fit tips
After forty years of making bras for running, we have some extra suggestions about how to deal with some common issues we face as women runners.
Changing out of a sweaty, tight sports bra is the worst — is there anything I can do?
Changing into and out of your run bra should be easy. If pullover bras don’t work for you, try styles with adjustable back closures, or even zip-front designs.
What’s the best way to deal with bra chafe?
Chafing is not something you need to suffer through! Try adjustable straps to fine-tune the fit, or free-cut finishing which practically eliminates edges on straps.
How do I keep my bra from getting too sweaty?
Get rid of boob sweat for good with styles that include mesh paneling, perforated cups, or strappy styles that minimize coverage.
Do bra seams all have to be so irritating?
Bras with nearly seamless finishing or bonded finishing — a fancy way of saying seams are adhered with heat instead of stitched — help eliminate seam-on-skin irritation.
What’s the best way to get smooth coverage over my nipples?
Stay confident in your coverage with styles that feature built-in molded cups or removable cups.
Need extra help getting started?
Now that you’re armed with all our best advice, you can use our Store Finder to treat yourself to an in-store fitting, get matched with your perfect Brooks Run Bra using our Bra Finder, or skip straight to the fun part and shop all our run bras.