We're all going to need to replace our sports bras at some point, so let's go over some of those signs:

• Are the bands of your sports bra are stretched out? If the straps over your shoulders or the band under your breasts are loose, your sports bra has reached the end of it's life. If you have a sports bra with adjustable bands, then this will take a little longer to happen and you have some wiggle room to tighten them.
• Is the level of support is wrong for your activity? If you used to do yoga and you've switched to HIIT workouts, you need a sports bra with more support. If you aren't sure what level of support you need, you can't go wrong with a high support sports bra.
• Does the smell never leaves, despite the number of washes? Look, everyone gets stinky when they're working out, there's no shame in that. But if you've washed your sports bra and it's still smelly, it's time for it to go. (Please note, I'm assuming there is nothing wrong with your washing machine and you didn't forget to add the soap. Not that I'm speaking from experience about that last one, cough cough.)
• Does it feel like it may not fit? Bodies change, there's no shame in this. If you find that you're popping out of your sports bra or the bra leaves red marks on you, it's too tight. If you feel it shifting around and not staying in place, it's likely too big (and/or stretched out).

In terms of replacing your sports bra, there isn't a magic number of how many times you can wear it before it needs replacing. If you're working out more frequently, they will most likely need to replaced more frequently. If you aren't sure if you should replace them, go through the bullet points above. If you find yourself answering "yes" to the questions, it probably needs to be replaced.