What Is ILD Mattress: A Complete Guide On Firmness

The answer to what is ILD mattress can be easier understood if you relate it to the firmness and softness of the bed. It is a measurement used for mattresses, especially foam such as memory foam and latex. We will discuss ILD ratings to help you understand them better without the confusing jargon. 

We also recommend that you check this guide on how to select mattress firmness. ILD also has some connection to the bed’s firmness, so you must understand the firmness scale as well. However, do note that ILD is not the only factor that affects mattress firmness. 

what is ild mattress


Everything To Know About ILD In Mattresses


What is ILD?

ILD stands for Indentation Load Deflection, and it will help you know how firm or soft a mattress is. You will also see the ILD value in other foam products, such as furniture and seats. For a deeper understanding, the ILD refers to how much force is needed to compress the foam. 



ILD is the same as IFD or Impression Force Deflection. The two ratings are interchangeable because they measure the force needed to compress a foam. However, you will see ILD ratings more commonly in mattresses. 


Low ILD vs high ILD

A low ILD rating indicates that it is a soft mattress, while a mattress with a high ILD rating is a firm mattress. The lower the ILD rating, the softer the foam, and the higher the ILD rating, the firmer the foam. Mattress manufacturers will also use quantitative ILD measurements such as soft, medium, medium-firm, and firm. 


ILD and firmness

The ILD value of the mattress will help you determine how soft or firm it is. However, ILD is not the only influential factor for firmness because it only pertains to a single foam layer of the mattress. The other materials inside it also dictate the overall firmness of the bed. 


What Are ILD Ratings?

The ILD rating or the 25% ILD rating is the number of pounds of pressure needed to compress a foam layer to reach a depth of 4 inches by 25%. The ILD ratings will help you determine if a mattress is soft, medium-soft, medium, medium-firm, and firm. It’s essential to understand the ILD ratings to help you know which mattress is best for sleeping.


Soft mattress

An ILD rating of 19, 20, and 21 means a soft mattress. These values might be too low for an ideal sleeping surface because your body will sink too deeply on the foam. If the foam doesn’t push back on the pressure, you’ll lose support, which is crucial for a good sleeping posture. 


Medium-soft mattress

A medium-soft mattress will have an ILD rating of 22 or 23. This mattress firmness is ideal for children or people who want a bit of sinkage without going too deeply. However, medium-soft beds are not that common compared to medium mattresses.


Medium mattress

The most common and favored mattress firmness is medium because it will work for almost all types of sleepers. A medium mattress has an ILD value of 24, 25, or 26. If you’re unsure of what mattress to get based on ILD rating, consider a medium bed. 


Medium-firm mattress

Mattresses with an ILD rating of 27, 28, 29, 30, or 31 are considered medium-firm. Compared to a medium bed with a value lower than 27, you won’t experience any sinkage with a medium-firm mattress. You might benefit from this mattress if you want a bed for back pain.


Firm mattress

A firm mattress will have an ILD value of 32, 33, 34, 35, or 36. It’s possible to see a rating over 36, but the bed will be too stiff for comfort. However, those who sleep on their stomach will benefit from a firm foam mattress to keep their spine neutral. 


What Is Firmness Rating 20 ILD?

A mattress with a firmness rating of 20 ILD is a soft bed. Those who want a sleeping surface that pushes them deeply will feel comfortable with a 20 ILD mattress. However, beware of sleeping in very soft mattresses because it doesn’t keep you supported, leading to long-term body pain. 


What Is The Density Of Foam?

The foam density refers to the quantity of the foam per measurable size. For example, if you weigh a block of foam measuring a particular dimension and it’s 3LB, it has a 3LB density. The most common foam densities are 1LB, 2LB, and 3LB, but you can also see materials as high as 15LB. 

Do note that foam density doesn’t tell you how firm it will be. Instead, it gives you an idea of the longevity of the material. This is why high-density foams are often used for furniture because they can withstand the demand for usage. 



And that’s it! To recap the answer to what is ILD mattress is, it helps you determine how soft or firm the foam product is. The higher the ILD value, the firmer it is, and the lower the ILD value, the softer it will be. 

Do note that it’s not enough to look at the ILD ratings when buying a mattress. You should also consider its other materials to help you gauge its expected firmness. We also recommend familiarizing yourself with foam densities. 


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