Odors

• One of the simplest ways to know if your pillow needs to be replaced is by removing the pillowcase and taking a big whiff of the pillow itself. Many people regularly wash their pillowcases when they wash the sheets, leaving them smelling fresh. This is a great idea, but the freshness is masking the true smell of the pillow. Over time the oils from your skin, sweat, drool or other bodily fluids could find their way onto the pillow, soaking through the case and into the fabric itself. This could lead to mold or mildew inside the pillow, which typically causes an odor. When the pillow develops this musty smell, get a new one.
  
  

Folding Test

• A common way to test your pillow for support and proper firmness is the folding test. Fold the pillow in half lengthwise and then let it go. If the pillow springs back out to its normal shape, then it is probably still providing the support and comfort it should. If it remains folded in half when you release it, then the material is worn out and you need a new pillow.
  
  

Pillow Gets Heavy

• A new pillow typically weighs about 10 ounces, according to the Sleep Better website. Three years later, the same pillow will weigh 20 ounces. The reason the pillow doubles in weight over time is because of dead skin cells, dust mites and the fecal matter left behind by those mites. It's disgusting and also unhealthy, and resting your head so close to this material can lead to allergies or asthma in some people. If you notice your pillow weighs more than it used to, replace it.
  
  

Comfort

• Perhaps the easiest way to determine if you need a new pillow is to think about how good you are sleeping. If you toss and turn because your neck is not supported comfortably or you wake up with neck and shoulder pain from improper support, then your pillow might be the problem. If you are getting complaints from your spouse about snoring, a new pillow might help, too.
  
  

General Timeframe

• Pillows should generally be replaced every six months to two years, according to "Happy Living Magazine." The time frame is dependent upon the quality of the pillow you buy. Cheap pillows are usually good for a year or less, while high-quality pillows can last for two years or more.