The answer lies in factors of your activity level, occasion and temperature. Usually washing your bra after 3-4 wears in winter would do.
But if your activity level is more and that causes more sweating than usual. Then your wash cycle gets increased. Similarly, when there is no sweat at all, the wash cycle gets decreased.
Some days you just wear a bra for 1 to 2 hours, on the other hand, some days you wear it all day long. So how do count wear?
Note: But they do need care. Again wearing the same for 3-4 days in a row is not recommended. The reason being elastic gets stretched out and needs rest to get back to the previous position. Gap of a day or two would be best between the two wears.
What Is Considered As One Wear?
Wearing a bra for just a couple of hours doesn’t really count as ‘wear’. A fancy bra you wear to dressy events can be laundered after 2-3 uses, but sports bras, on the other hand, should be washed after every wear (for obvious reasons!)
How To Wash Your Bra The Right Way?
Do you know you are doing injustice with your bra, by throwing them in a washing machine? They are not meant to be machine-washed. Continuing this practice may lead to early wear out of the bra.