There are a lot of reasons to choose wool when you're shopping for fitted hats: It's super warm, highly durable and looks appropriate with whatever you're wearing. Another of wool's qualities – the fact that it tends to shrink – is only a positive when you're stuck with a hat that's too big. In this case, you're in luck because shrinking a wool fitted hat can be accomplished with nothing more than a washer and dryer.

Many fashionistas have mourned a wool sweater that accidentally went into the dryer and came out child-sized. The fact that wool can shrink in the wash is the reason that so many woolen garments are labeled as being safe for dry clean only. Woolen fibers are sensitive to heat, water and agitation. When they're exposed to these forces, the fibers shrink and lock together, so the shrinkage can't be easily reversed even once the garment is dry.

That's bad news in a lot of wool-related laundry mishaps but useful for anyone who is trying to shrink a wool fitted hat. Still, it's important to understand that "wool" can mean lots of things. Check the label for any information about what type of wool you have. Certain types are more likely to shrink than other types.

For example, Angora wool (which comes from rabbits) is very shrinkable. Fuzzy yarn, from which a lot of hand-knitted hats are made, tends to be made from soft wool that's also prone to a lot of shrinkage. Worsted wool, which is made from a different kind of yarn, is smooth and almost sleek-feeling. Hats made of this type of wool won't shrink as much as those made of fuzzy wool.

The forces that cause woolen fibers to shrink are heat, water and agitation. Translation: the washer and dryer.

The simplest way to shrink a fitted hat is to simply wash it in a washing machine on the gentlest setting using warm water. This combination provides enough heat and agitation to hopefully cause some shrinkage but not enough to damage the hat. If you're running the hat through the washing machine in a load with other clothing, use a gentle detergent.

Next, put the wet hat in the dryer on low heat. Again, very high heat could cause damage. Ideally, you'll dry the hat alone. After the first 15 minutes or so, pull the hat out every so often to try it on. If it needs to shrink more, put it back in the dryer for a little longer.

Has your wool hat been washed before? If not and the wool is dyed, there's a chance that the dye will run in the wash and potentially stain other garments. One option is to hand wash the hat with gentle detergent and rinse it thoroughly to hopefully rinse away any excess dye.

Also, it's important to remember that there's always a chance that you'll damage your hat by washing and drying it. Don't take this risk with a hat that's very expensive or has great sentimental value. The washer and dryer is also not the best solution for shrinking a shaped wool hat like a fedora or trilby. In that case, it may be more useful to use hat sizers to change the fit.