Memory Foam Mattress Buying Guide

What is memory foam?

Memory foam is a viscoelastic material. “Visco” means that it is thick and resistant to change, and “elastic” means that it reforms its shape after being distorted. Normal foam is merely elastic, while memory foam can “remember” the shape of an object pressed against it (such as a sleeping human). This “memory” means that memory foam can support the weight of sleeping body in a much more even, balanced manner than any normal mattress.

There are many who find their lives greatly improved by switching to a memory foam mattress. People suffering from chronic back, shoulder, neck, or other joint pain are almost always delighted by the way memory foam eases their discomfort. Others who are uncomfortable on standard mattresses or who are easily awoken by their partner's movements find memory foam mattresses invaluable.

Memory foam comes in many different feels. These are determined by density, firmness, and thickness.

The history of memory foam.

Memory foam was originally developed by the United States space program to dampen impacts and protect its astronauts. Originally known as CONFOR foam, it helped keep astronauts safe during take-off and landing.

It then spread to other areas where high g-forces were experienced, such as seating in airplanes and helicopters, as well as situations where people had to remain immobile for long periods of time, such as in hospital beds.

As the manufacturing process became easier, enterprising engineers brought it into the public market, where it quickly revolutionized the sleep industry.

What you need to know about density.

Density is the measure of just how much material is in each cubic foot of your mattress. Mattresses foam usually comes in densities of 3 to 7 pounds per cubic foot—industry leaders Tempur-Pedic® and Amerisleep use foam that's between 4 and 5.3 pounds per cubic foot.

More density is not always better! Lower density foam tends to have less “memory” and is softer than higher density foam. Foam with a density greater than 5.3 pounds per cubic foot tend to make you feel “stuck” or “trapped” in your bed once it has adjusted to your body.

FACTS

  • Density affects memory characteristics
  • Affects cost of the mattress
  • Ideal density and industry standard is between 4-5.3lb
  • Denser foams will cause the user to feel more "stuck" in the mattress

FICTION

  • Higher density is always better
  • All density is created the same
  • Density is a reliable indicator of quality
  • Density is the only factor that affects the comfort.

How firm should my mattress be?

The firmness of memory foam decreases as temperature increases. That's why we use thicker foam on the top of your mattress (where you body will heat it up) than on the bottom.

How do you decide what level of firmness is right for you? A great place to start is your current bed—is it too soft? Too firm? Aim to fix whatever problems that you're having now, first. Then, think about your usual sleeping position. Back sleepers will usually need a firm mattress, while side and stomach sleepers should consider something softer.

And if you don't get it exactly right the first time, don't worry! Our 90-day guarantee means that you can trade mattresses until you find the one you need.

THE BEST FIRMNESS

Consider your body's shape and match it with the proper firmness to give you proper and natural spinal alignment.

How thick should my mattress be?

It's not just about firmness and density—the thickness of each layer in your mattress has a powerful effect on how it feels.

Using customer feedback and our own research, we've determined that anywhere from 2” to 7” of memory foam is just about right for your top later. The thinner the top layer, the closer you'll be to the support layer underneath, and the firmer your mattress will feel.

Memory foam mattress thickness guide

IFD: measuring firmness.

The short version? The higher the IFD number is, the firmer your mattress. The lower the number is, the softer your mattress. Ratings above 30 are usually considered “firm,” while anything below 25 is “soft.”

For those who are a bit more curious, here's the full explanation: IFD stands for indentation force deflection. It's a measurement of the amount of force required to push a round testing foot into a foam sample to a certain percentage of its thickness. However, it's not a measurement of density, and so a low density foam with a high IFD rating can still feel soft when compressed.

This is another reason why we offer our 90-day trial of any mattress you order. With so many factors to consider, it's much easier to just try and bed and see if it works for you.

IFD's Effect on Firmness

A higher number is firmer while a lower number is softer.

Should I replace my box spring?

Not always! Your box spring may still have years of life in it. Here are the things you'll want to look for:

  • Less than 8-10 years old
  • Steady, flat, and smooth on top
  • No broken springs
  • A solid construction, with no broken pieces, splinters, or cracks

If it's still in good shape, you may be able to reuse it. Be careful, though, because a worn-out box spring will prematurely age your mattress, damaging your investment and keeping you from getting good sleep. You may save money in the end with a quality foundation.

When in doubt, throw it out.

Compare our mattresses

Model
Reviews
Firmness
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Sleep Style
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Profile Height
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Layer Construction
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Celliant® Cover
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Fire Guard
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Bio-Pur+™ Comfort Layer
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Bio-Pur™ Comfort Layer
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Active Flex Layer
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SMT
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Affinity Layer
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Bio-Core™ Base Layer
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Price1 (Mattress Only)
Review Snapshot
Medium
Side, Combo
12-inch
3 layers
Celliant® infused breathable cover with hazel wave design
Green Guard fire sock
N/A
3 inches
4.0-lb density
10 ILD
N/A
No
2 inches
1.5-lb density
22 ILD
7 inches
1.5-lb density
35 ILD
Twin: $699 USD
Twin XL: $799 USD
Full: $999 USD
Queen: $1099 USD
King: $1399 USD
California King: $1399 USD
Split King: $1499 USD
Show moreless sizes Shop Liberty
Review Snapshot
Firm
Back, Combo
12-inch
2 layers
Celliant® infused breathable cover with chocolate wave design
Green Guard fire sock
N/A
3 inches
4.0-lb density
10 ILD
N/A
No
N/A
9 inches
1.65-lb density
40 ILD
Twin: $719.2 USD
Twin XL: $819.2 USD
Full: $1019.2 USD
Queen: $1119.2 USD
King: $1419.2 USD
California King: $1419.2 USD
Split King: $1519.2 USD
Show moreless sizes Deal of the day! Shop Revere
Review Snapshot
Soft
Side, Combo
14-inch
3 layers
Celliant® infused breathable cover with white floral design
Green Guard fire sock
2-inches
4.0-lb density
11 ILD
N/A
3 inches
3.0-lb
11 ILD
Yes
N/A
9 inches
1.65-lb density
40 ILD
Twin XL: $1599 USD
Queen: $2099 USD
King: $2349 USD
California: $2349 USD
Split King: $3198 USD
Show moreless sizes Shop Independence

1Prices reflect current promotion or sale.

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Get answers about Amerisleep mattresses before you buy.

1-800-500-4233
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