Most pillows only last between 18 months to 3 years on average, before their filling and material begin to wear due to continued use and compression. Although some may last longer, a good rule of thumb is to test your pillow life regularly starting after 18 months of regular use, and see if you should be replacing it. To do this, you can fold your pillow in half and see if it ‘bounces’ back to shape. If not, then you may want to consider replacing it. While some pillows can be machine washable, it's best to carefully read the cleaning instructions on the label to advise what's the safest washing method for yours. Materials such as memory foam are not machine washable, and doing this may damage the material and shorten the pillow's lifespan dramatically.