Consider the Quality of the Bra and How Often You Wear It
Many people have a difference in opinions when it comes to replacing your bras. Many will say to replace them every three months, others will tell you every six months. I personally think that it all depends on a few things. You have to take into consideration the quality of the bra and how much you wear it. These can have a great impact on the life of the bra.
I have bras that I have had to replace more often than other. Some have needed replacing every three months and some I haven't had to replace for a couple of years. My every day go to bras like my Natori bras are replaced more often due to the many wears. I wear these more often because I have them in nude which look good under almost everything I own. I also have bras like my Le Mystere 9955 which is one of my favorite t-shirt bras but doesn't get as much use as my regular bras because I own it in black so I tend to wear it with my dark tops, etc. I've had this bra for a little over three years now and I think it is time to get a new one. As you can see since I tend to wear my Natori bras more often they need replacing sooner than my Le Mystere which gets less use therefore has lasted longer.
Another factor that may contribute to having to replace your bras more often would be the way you care for your bras or the lack of care. Prior to getting properly trained on lingerie and how to care for my lingerie I use to throw my bras in the wash and dryer. This caused many of my bras to lose support and lose the underwire. This cost me lots of money in the long run. A good way to preserve the life of your lingerie is to wash it by hand so that it won't snag on anything. I also recommend washing them with mild detergent instead of using harsh soaps or Woolite because these tend to clog the pores of the fabric and cause the elastics to break easier therefore losing the support. I recommend using baby shampoo or my favorite lingerie wash - Forever New fabric care.
The quality of the bra is also a BIG factor in how often you have to replace your bras. I've owned poor quality bras that have hit the garbage can after my first wear. Some of the reasons have been because of the poor quality which tends to cause much discomfort and at times pain. Then there is the annoying underwire popping out through the fabric, the non supportive band or the flimsy cups which don't firmly hold the breast. Any of these reasons have caused me to replace my bras more frequently at one time or another.
In conclusion, bras you wear only occasionally may last you many years but bras you wear a lot (like your work bras) need to be replaced frequently so that your breasts have consistent and adequate support. Also, if you are replacing bras more than every three months, you may want to consider changing the style or brand. Finally, your bras will last longer if you rotate them - meaning "one on, one in the drawer, and one in the wash" - this will give your bra and the materials or elastics time to "recover".