We all use a variety of different factors to determine whether or not we should get rid of old clothes. Instead, try using the criteria that got it there in the first place: "Would I buy this if I were shopping?"
Photo by Lara604.
Once we've accumulated a bunch of clothing, the decision-making process changes dramatically from the cost/benefit analysis we did when first purchasing it. We have emotional attachment for certain items or have plans to save it for special occasions/when we lose weight/etc. There's nothing wrong with keeping a few items around, but if you have a large amount of clothing in your closet that you wouldn't buy today, that may be the first sign that you should get rid of it. If this doesn't work for you, you can always try the hanger trick.
30sec Tip: Cut Down Your Closet by 25% [Lifehack]