Everytime I wear it?

Once a week is good enough. Unless you sweat like nobody's business and then cannot stand the smell of your binder
I wash it once it stops binding well, usually every two weeks (if I can even remember to). Washing it makes it bind tighter, and go back to it's original tightness.

ya i wash mine once a week
it stops binding well after around 4?days

Can you smell it?  Then it's time.

I wear a tank top under mine always so I wash it when it starts to smell or its stops binding well. I have 3 that I rotate through so I usually wash one a week.

Totally depends if you wear something under it or not.  I wear a shirt under mine and wear mine 2 or 3 times before washing.  Once summer comes back around I'll be back to washing daily.

It also depends on what material the binder is made out of.

I find that the tri-top doesn't absorb sweat and odor particularly fast. Meanwhile, if I so much as breathe near a compression shirt of mine, it smells.

I have yet to find that my tri top picks up smell. I wash it when I remember too, every few weeks typically.

I mostly wear compression tanks and wash after every wear.....

I tend to wash it once a week or when I can start to smell it, whichever comes first.

Has anyone every used Febrze?

http://en.wikipedia.org/wiki/Febreze

I recently wanted to wear a particularl shirt. It was, frankly, smelly. used this stuff and it worked!

Not suggesting it as a subtitute for washing, of course, but in a pinch, so handy.

I wash mine after wearing it maybe 4-5 times

I'm with Tad. I have a tri-top, the worst it's ever gotten is a tad musty. I feel slightly unhygienic washing mine infrequently, but the laundry situation in my house is bad to start with. Anyway, it's better than when I was wearing one sports bra 24/7 as long as I could get away with it. My dysphoria was unbearable without it, those days.

Depends.  I have two binders and one I wash more than the other.  I'm a martial artist and it's considered good etiquette to try and keep as much body odor off as possible considering the amount of close contact one engages in.  So the one I wear for when I work out and teach I wash every other day I work.  The other binder I use more often for when I'm going out and tends to carry a lightly layered scent of various deodorants or colognes, once I start not liking what it smells like I wash it.  I'm pretty sensitive to smells though so I may be washing my binders more than necessary for purely hygiene reasons.

How do you guys wash your binder to get it to bind tightly again? Do you machine wash them? I'm scared to put mine in a washing machine, I can't afford for it to wear out quickly. Does hand washing it help it renew it's bindyness?

you can usually machine wash pretty easily, I just hand wash because I hand wash a lot of my clothing, and to save water and money.  I find air drying seems to make the biggest difference in renewing a bit on tightness.

For the longest time I was afraid to wash my binders for fear of shrinking, etc. Then I started washing them but not putting them in the dryer, or pulling them out of the dryer after 10 minutes or so. Eventually, I got tired of all that fussin' (seemed so girly) and just started to wash them and dry them with a regular load and they are fine--the dryer actually tightens them up a bit, and it's fine.

BUT!

Remember that thread of "You know you think like a guy when..."? Well, you know you think like a guy when you put all the different colors together into one big load, so now I have 3 Underworks T-shirts that are....pink! What a dope. Must have put them in with a red T-shirt. So, if anyone knows how to get them white again, I'd be most grateful! They've been washed a million times since then, with bleach too...and sadly, still pink!  What a dummy!!