How Should Sports Bras Fit?
To find the right bra for you, you need to determine your size, as well as the activity you’re using it for. We’ve put together this guide to help you determine if your bra fits properly.
Gear
Your Guide to the Perfect Sports Bra Fit
You probably know the importance of proper fit when it comes to your running shoes. And finding the right fit in a sports bra is just as important! Many women don’t know what size bra they should be wearing, or struggle to find the right fit. Wearing an uncomfortable bra can cause breast pain, chafing and distraction mid-activity. It can also cause long-term damage to your breasts, which nobody wants!
So, chances are, if you’ve never been fitted for a sports bra, you could be running in the wrong size. Fleet Feet specializes in bra fittings. You can schedule an appointment at most locations to make sure you get an Outfitter that you’re comfortable with.
To find the right bra for you, you need to determine your size, as well as the activity you’re using it for. If you’re doing a high-impact sport, like running, you need a high-impact bra designed to comfortably support you for that type of movement.
We’ve put together this handy guide to help you determine the right size, and know how to tell if your bra fits properly.
Gather a few measurements
To find the optimal size, grab a measuring tape and gather two measurements. You'll also need to do a tiny bit of math.
- Find your band size. Wrap the tape snugly around your ribcage, just above your breasts, keeping it level across your back. Round down to the nearest whole number and record that measurement.
- Measure your bust. Wrap the tape around the fullest part of your bust, keeping it level across your back as well, and record that number.
- Find your cup size. Subtract your band measurement from your bust measurement. The difference in inches tells you your cup size (see chart to the left).
For example, if your band measurement is 36 and your bust measurement is 39, the difference is three inches. Each inch of difference moves you up a cup size starting at A, so three inches puts you at a C. A 36C is a good size to try first.
Once you have an idea of what size you need, try on a few bras. Sizing varies by brand, so give yourself room to compare fit and feel before settling on one. Need help finding a style? Browse our full selection of sports bras to find the fit and support that match your workout.
| Difference in band size | Cup size |
|---|---|
| 1″ | A |
| 2″ | B |
| 3″ | C |
| 4″ | D |
| 5″ | DD |
| 6″ | E |
| 7″ | F |
Low-, medium- or high-impact?
Your activity and your breast size both determine the level of support you need. Most sports bras come in three categories: low-impact, medium-impact and high-impact.
As you might guess, a low-impact sports bra is ideal for squats at the gym or a yoga class.
A medium-impact sports bra works well for hiking and cycling.
For most women, a high-impact sports bra is ideal for running, mountain biking, dancing, and other intense cardio activities.
However, many smaller-chested women will have no problem performing high-impact activities (like running) in a medium-impact sports bra.
Encapsulation or compression?
Bras come with a variety of support options that use encapsulation, compression, or combination of the two. Let’s break down the differences.
1. Encapsulation bras use individual cups to support breasts by encapsulating them separately. This offers minimal breast support (everyday bras are often purely encapsulation bras). Encapsulation bras are ideal for low-impact activities.
2. Compression sports bras work by compressing the breasts to prevent movement. Most compression bras don’t have hook and clasp closure. Instead, they’re easily pulled over the head. Compression bras are ideal for medium-impact activities.
3. Combined compression and encapsulation bras offer a combination of these two support systems that makes them ideal for running and other high-impact activities.
How can you tell if your sports bra fits correctly?
A properly fitted bra should feel comfortable. Here are some things to look for in the right fit:
- When you try on the bra, run in place, twist, bend and jump. Some breast movement is natural, but you shouldn’t feel a lot of bouncing.
- The fit should feel snug, yet comfortable. If you can hardly breathe, the bra is too small.
- The band should lie flat against your body and not raise up off of your skin.
- You should be able to slide two fingers between the band and the body.
- Shoulder straps should lie flat and not be twisted.
- Straps should not dig into your shoulders.
- The cups of the bra should fully cover your breasts. If your skin is showing around the edges of your bra, you might need a bigger cup size for better coverage.
When to replace your sports bra
With every wear and wash of your sports bra, the elastic fibers gradually lose their ability to spring back. As a general guide, if you wear the same sports bra several times a week (for example, running four days a week) consider replacing it every six to eight months.
However, a sports bra’s lifespan depends on how often you wear it, how you wash and dry it, and how many bras you rotate between. Some regularly worn sports bras may last closer to 12 months, so use the fit and condition of the bra, not just its age, to decide when it is time for a replacement.
A quick test is to jog or jump in place. If your bra no longer feels as secure and supportive as it did when new, it may be time for a replacement. Read our guide on when to replace a sports bra for more signs to look out for.
(This article was reviewed and updated by Madeline Gentzel on July 29, 2026)
