Chances are you've heard that you're supposed to replace your mattress every eight years, but how long do memory foam mattresses really last? Because memory foam mattresses can be expensive, depending on what type you buy, it's not something that you want to replace often. The good news is that if you do your research and keep these tips in mind, you can find a mattress that will last for many years to come.  

Foam Density Affects Mattress Longevity  

When buying a memory foam mattress, it's important to understand that foam density has the biggest impact on the longevity of the mattress. If you're comparison shopping and find one mattress that costs significantly less than all the others, it's probably because it's made from low-density foam. 

Density is calculated by measuring the weight of one cubic foot of foam. A foam is considered low density if it's between two and three lbs. A foam is considered mid-to-high density if it's between four and five lbs. A low-density mattress will typically last around four to six years, while a high-density mattress will usually last around eight to ten years. Therefore, the higher the density of your mattress, the more durable your mattress will be.  

Properly Care for Your Mattress 

Regardless of the density of your mattress, if you want it to last as long as possible, it's imperative that you take the proper steps to care for your mattress. There are three things to consider when protecting your investment: using adequate support, safe guarding it from spills and stains and rotating it for even wear.  

After buying a new bed, use this guide to find the best foundation to support your memory foam mattress. A flat platform, slatted base, box spring, adjustable base or a floor will all work fine to ensure that your mattress lays flat and is evenly supported. If you fail to provide a solid foundation for your mattress, it could void your warranty. 

To protect your investment, apply a mattress protector to your new bed. A protector will serve as a waterproof barrier between your new mattress and potential stains, like greasy pizza or pet urine. It will also protect your mattress from body sweat and dead skin cells that may soil your mattress over time. The best part of applying a mattress protector? When accidents do happen (and they will) it's easy to wash!  

If you've ever had an inner-spring mattress, you may have squeezed more life out of it by flipping it over every now and again to feel like you're getting more support. Well, with a memory foam mattress you don't need to do any heavy lifting. All you have to do is rotate your mattress 180 degrees every six months to guarantee even wear.  

Read the Warranty Before Buying 

Buyer beware. When selecting a quality memory foam mattress, look for one that includes at least 10 years of full coverage. A 10-year warranty indicates that the manufacturer expects the mattress to provide the proper amount of support and comfort for around a decade.  

Replace Your Mattress When Needed  

Finally, even though 10 years is the average lifespan for a memory foam mattress if you buy dense, high-quality foam and take good care of it, there are exceptions. If your mattress is obviously sagging at some points, has excessive stains or you find that you're simply no longer sleeping well, it may be time to replace your mattress.