When you’re getting ready to buy a new bed, one of the first decisions you must make is whether you prefer a firm or soft mattress. 

But what’s the difference between the two?

Mattresses described as “plush” or “soft” feel softer on the sleeping surface, cushioning and cradling you while you sleep. One of the primary benefits of a soft mattress is pressure point relief. 

However, if you need more support from your mattress, you’ll be better off with a firm bed. While sleepers who prefer plush mattresses sometimes describe them as stiff and uncomfortable, firm beds create more neutral spinal alignment for stomach and back sleepers. Within this guide, we’ll highlight firm vs. soft mattress differences and discuss various mattress firmness levels on the market, revealing the pros and cons of each one.

Firm vs Soft Mattress: Which is Best for you?

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Mattress Firmness Levels: Soft, Medium, and Firm 

For the most part, mattress descriptions generally begin with the words “soft” or “firm.” In truth, far more subtlety exists in terms of the degrees of softness or firmness. In other words, the firmness (or softness) of a mattress really falls into a spectrum.

Here’s a look at the proprietary Slumber Yard spectrum for the Original Casper mattress.

Firm vs soft scale for the casper mattress
Firmness scale for the popular Casper mattress

What makes a mattress firm or soft?

Of course, the biggest difference between firm and soft mattresses is how they feel. Soft beds will sink in when you sit or lay on them, while firmer mattresses will retain their shape better.

Mattress manufacturers use different materials to achieve a soft or firm feel. For example, memory foam can have a soft marshmallow-like feel that contours around your body. In contrast, other beds have a high-density polyfoam layer that creates a firm and supportive feeling.

Additionally, soft mattresses and firm mattresses each adhere to different sleep styles. For example, mattress shoppers that sleep on their side often wonder whether it’s best to get a firm or soft mattress for side sleepers. During the night, a side sleeper puts pressure on shoulders, elbows and hips. By sleeping on a softer mattress like Casper Nova, these pressure points are cradled and cushioned as the mattress contours to the curves of the body. 

By the same token, the support given from a firm mattress works best for stomach and back sleepers. While a soft mattress drops the body down, a firm mattress provides the support needed to keep the spine aligned. Finally, mattresses described with medium firmness combine soft mattress elements to offer pressure relief without compromising support. The idea, really, is to offer the best of both worlds.

Benefits of a Firm Mattress

There are many reasons to consider a firm mattress. Here’s a look at the top benefits of a firmer bed: 

  • Reinforcement for the back and spine. You might have heard that a firm mattress is better for back sleepers. In reality, firm beds are great for stomach sleepers, back sleepers, and heavier individuals looking for more support and proper spinal alignment. Maintaining spinal alignment prevents tightened muscles and back pain, which is especially important for people who may suffer from a condition like Sciatica
  • Better for sleepers with higher body weights. Instead of excessive compression as a heavy individual lies down, a firm mattress compresses less because of the supportive design.
  • Cooler than soft mattresses. With a firm mattress, you sit more on top of the mattress rather than sink into the comfort layers. As a result, less of your body is in contact with the mattress material, keeping you cooler at night.

Cons of a Firm Mattress

While a firm mattress offers the benefit of support, mattresses designed with excessive support features can amount to too much of a good thing. Here are a couple of the downsides of firm mattresses. 

  • Not ideal for combination sleepers. Really firm mattresses may be too much for some sleepers, especially if you switch positions here and there during the night.
  • Not plush enough for restorative sleep. Although some individuals benefit from hard-support firm mattresses, many sleepers need at least a little bit of cushion to achieve comfortable, restful sleep.

Pros of a Soft Mattress

For some people, firm mattresses are just too rigid or uncomfortable. In these cases, a soft mattress is a better option. Here are a few of the main benefits of soft mattresses: 

  • Soft and contouring feeling. For sleepers who enjoy a mattress that cradles their body, soft mattresses provide a deep cushion hug or a traditional deep contour feel, such as what you get from memory foam mattresses.
  • Can be beneficial for pain relief. The bed acts to cradle and cushion throughout the night, regardless of your sleeping position. This firmness level is really pressure relieving, which can help those who have arthritis or joint pain.
  • Better for petite sleepers. Especially for individuals with bodyweight on the lower side of the scale, a soft mattress is worth considering as a firmer mattress style provides less give than softer mattresses do.

Drawbacks of a Soft Mattress

With that said, soft mattresses aren’t right for everyone. Here’s why someone might decide against a soft bed: 

  • Less support for heavier body types. The primary drawback of a soft mattress goes to the support it offers. More precisely, the softer a mattress is, the less support you’re going to get. This might not be ideal for somebody who weighs over ~230 lbs because they need a mattress that proves to be durable and supportive under more pressure.
  • Only suited for specific sleeper styles. The sinkage that accompanies extremely soft mattresses creates body misalignments that can create uncomfortable sleep and general body achiness for those who aren’t strict side sleepers with petite to average body types.

Who Should Buy a Firm Mattress?

  • Stomach and back sleepers. For these sleepers, it’s all about spinal alignment. A softer mattress sinks the body out of alignment through a lack of spinal support, but a firmer mattress provides the spinal support necessary to awaken rejuvenated.
  • Hot sleepers. With a firm mattress, sleepers don’t sink in as much as they would with softer beds. As a result, the mattress won’t swaddle them as much, keeping them cooler.
  • Heavier people. People who weigh more than 250 lbs put more pressure onto beds than lighter folks. But a firm bed will support their weight better, preventing them from sinking in too much.
  • People with certain back problems (like Sciatica). A sleeper’s spine should stay aligned with a firm bed, which helps protect against back pain and tightened muscles.

Who Should Buy a Soft Mattress?

  • Side sleepers. Side sleepers put pressure on the shoulder, elbow, hips and sometimes the knees. In these cases, a firmer mattress creates more pressure while a softer mattress relieves the pressure. 
  • Petite and average-sized sleepers. People in the small or average-sized weight category won’t put too much pressure on a soft mattress. In a soft bed, they should feel comfortable, but not like they’re sinking.
  • Couples. Softer beds are better at motion isolation, so one partner won’t be disturbed if the other tends to toss and turn or gets out of bed frequently.  
  • People with arthritis or joint pain. Since soft mattresses are excellent for pressure relief, they’re usually the right choice for people struggling with aches and pains.

When To Buy A Mattress With A Medium Firmness 

A mattress designed with a medium firmness level essentially establishes a compromise between support and pressure relief. As mattresses with a medium level of firmness provide an optimal design for an estimated 80 percent of sleepers, individuals looking to purchase a new mattress may want to consider their options in this mid-tier range. 

Here are the groups that will likely enjoy a medium firmness mattress.

  • Combo sleepers. Many people don’t conform to a strict sleeping position. With a medium mattress, combination sleepers maintain pressure relief while lying on their side while maintaining spinal alignment while lying on their back or stomach.
  • Small or average-sized body types. If you’re petite or under around ~200 lbs, we especially think you can get away with a mattress with a medium firmness regardless of your sleeper type because it’s so balanced.
  • Couples with different sleeping styles. By combining features that provide both cushion and support, a mattress in the medium firmness category works to provide comfort and restfulness all the way around.

Firm Or Soft Mattress: Verdict

Finding the right mattress for a comfortable and restful sleep comes with no shortage of options. As manufacturers develop a range of products that go from very soft to extra hard, consumers in the market for a new mattress do well to understand the personal elements that play into the soft-to-firm spectrum.

Beyond how comfortable a mattress feels when initially going to bed, the real test of whether a mattress is a good fit depends on the level of refresh and rejuvenation felt on waking. Whether too soft or too firm, sleeping on the wrong mattress results in poor sleep and an achy body. Make sure you’re considering your sleeper type, body type, and the needs of others who might share a sleeping space with you.

Is it better to sleep on a hard or soft mattress?

Body type and sleeping style determine whether a hard or soft mattress offers better sleep.

Will my weight affect how a mattress feels?

Your weight determines how much sink the mattress offers. An individual with a lower body weight stays more atop a mattress while an individual with a higher body weight sinks more into the mattress.

What firmness is best for back sleepers?

Back sleepers require the support of firmer mattresses for proper spinal alignment.

What firmness is best for side sleepers?

Side sleepers require the cushioning of a softer mattress for pressure point relief.

What is a double-sided mattress?

A double-sided mattress essentially acts as two mattresses in one. Each side provides a slightly different firmness level, allowing sleepers to adjust the mattress with fluctuations in the body or preferences.

How firm should mattress be?

It depends on a person’s weight and sleeping style. As a general rule, heavier folks should opt for firmer beds. Same with back and stomach sleepers. A mattress with a medium-firm rating could be a good fit for those in-between average and heavy body weights.

Should couples choose a firm or soft mattress?

Soft mattresses are better at isolating motion, so one partner is less likely to wake up if the other moves around. But if one partner likes firm beds and one likes soft beds, a medium firmness would be a good compromise.

What’s the scale for measuring firm vs. soft mattress levels?

At the Slumber Yard, we use a spectrum that ranks mattresses as either: soft, medium-soft, medium, medium-firm, or firm. Some mattresses are rated in between levels.