Mattress Firmness Guide

Your mattress is the most important comfort element that you'll need to think about when it comes to your bed, and there are lots of different materials, sizes and firmness available. In particular, you'll need to find a mattress that will support your body as you sleep, no matter if that's on your side, back or front. While you'll want to consider the depth and type of mattress, you'll also need to know about the different mattress firmness that are available.

Getting a good night's sleep is more important than just waking up feeling refreshed, with the Sleep Foundation explaining that it is crucial for better concentration and mood, as well as lowering the likelihood of you developing serious medical conditions. While your sleep environment needs to be just right — with limited light and noise disruptions — it's also necessary that all aspects of your bed are comfortable.

In this guide, we'll be sharing our tips for picking a mattress firmness to suit you. We'll cover:

What is a comfort/firmness rating?

How firm your mattress is will directly impact the quality and quantity of your sleep, as well as whether or not you wake up feeling sore and achy in the morning. At Dormeo we give a guide to the firmness of each mattress with a comfort rating. Generally, mattress comfort ratings can range from soft to extra firm, with some universal comfort models that are made to mould to a range of bodies.

Although the firmness or comfort rating you pick will generally be dictated by your height, weight and personal preferences, different firmnesses can also be better suited to different types of sleepers. This is because each sleeping position — back, front and side — puts pressure on different parts of the body.

What is a comfort/firmness rating scale?

There are some key terms that mattress manufacturers will use to refer to their products, including ‘plush’ and ‘firm’. But without some clarification, it can be difficult to know what is meant by these ratings and whether they'll be suitable for you personally.

Manufacturers may use numbers or words to describe the firmness of the mattress. In the below table, we use a description across a scale of 5. Although this can sometimes be subjective, this is more or less the universally accepted scale for mattress firmness:

Firmness Rating What it means
Soft These mattresses are incredibly sinkable but offer the least support of all mattress types, so are rarely suitable to buy for many sleepers, as most people need at least a little support.
Medium/Soft A medium/soft mattress will feel plush and sinkable, offering a good deal of body contouring. This makes them good for those who like their body to feel hugged by their mattress.
Medium Medium mattresses strike the perfect balance between soft and firm mattresses. They have some plushness but less sink, so are a good all-rounder for people who sleep in a variety of positions.
Medium/Firm A medium/firm mattress offers more support with less give than softer variations. These don't tend to have the contouring properties of softer ones, but they do have some cushioning to alleviate any pain at pressure points while keeping the spine aligned during sleep.
Firm Firm mattresses have less sink and so can keep a sleeper’s spine aligned more strictly if they sleep on their front or are heavier. It is often thought firm mattresses are good for sleepers with a bad back, however this may not always be the case.

Mattress ratings for side sleepers

Side sleepers place all of their weight on their shoulders and hips when they're resting, which can give them back and shoulder pain as the years go on. As there is so much pressure on these areas, you must alleviate this with a softer mattress that gives you more cushioning and allows the body to sink into it slightly. However, you mustn't choose one that's too soft, as this can result in spine alignment issues and create even more aches and pains.

If you're a side sleeper, we would generally advise going with a medium/soft or medium mattress — depending on your body compensation, this will be firm enough to stop your body sinking into the mattress entirely, but will be plush enough to alleviate pressure and pain as you sleep. Side sleepers will also benefit from choosing mattresses made from materials that will mould around the body for maximum comfort, like latex or memory foam.

For more information on creating the right sleeping environment as a side sleeper, check out our recommendations for the best mattress and pillows for side sleepers.

Mattress ratings for back sleepers

Considered to be the best sleeping position for comfort and support, sleeping on your back means you are more likely to find different firmness levels comfortable. This means that back sleepers are more likely to be able to choose a mattress comfort rating based on feel rather than proper spine alignment. For instance, a back sleeper could love the luxury “sink-in” feeling of a medium/soft mattress more than a medium firmness mattress, despite both offering proper spine alignment.

However, there are still some restrictions of being a back sleeper. For one, it's easy for the heavier body compositions to lose alignment if the mattress you're sleeping on is too soft, as your shoulders and legs tend to sink lower which creates an unnaturally curved spine shape. Because of this, back sleepers can report waking up with a sore and achy back.

For this reason, we recommend going with a mattress firmness of medium/soft, medium or medium/firm depending on your personal preference. The comfort level you pick will likely be dictated by your weight: the heavier you are, the firmer you'll need your mattress to be.

For more information on creating the optimum environment for a back sleeper, take a look at our recommendations for the best mattress and pillows for back sleepers.

Mattress ratings for front sleepers

When you sleep on your stomach, your core sinks deeper into the mattress while your arms, legs and head are elevated. This typically results in front sleepers having spinal alignment issues, as well as neck and back pain. Given the additional pressure that front sleeping puts on your muscles, joints and organs, it's particularly important to alleviate this by choosing the right mattress firmness — which in this case, is a firmer mattress on the rating scale. To stop pressure building on the hips and shoulders, pair this with a good layer of cushioning like a mattress topper.

As a front sleeper, your mattress needs to help you maintain your natural spine alignment, so you don't get bad posture or wake up in pain. Our Octaspring mattresses are ideal for front sleepers as they are thicker and so have more comfort layers to keep your body balanced, as well as being made with breathable sleep technologies.

If you'd like to know more about our recommendations for front sleepers, be sure to check out our guide to the best mattress and pillows for front sleepers.

Do you share your bed with a partner?

Alternatively, you could get a customisable one that lets you each have a different firmness on your side of the bed — our S Plus memory foam mattress is perfect for ensuring you both get the perfect mattress firmness within the same bed.

When you share a bed with a partner, you also need to make sure that there’s enough space to you both to fully relax. While a double mattress should offer ample space for most co-sleepers, taller or heavier co-sleepers will likely appreciate the extra room that a king-size mattress offers.

What is your weight?

Your weight will be what determines how much pressure you apply to the mattress, so it's important that you consider a mattress firmness that will alleviate this pressure and align your spine correctly. Your body shouldn't feel like it is sinking too deep into your mattress. Instead, your body should feel well balanced across the top of the mattress.

Many heavier sleepers (over 16 stone) will usually benefit from a larger, deeper mattress — preferably one which is at least 25cm deep, as this will provide better support. If you’ve got room, we’d also recommend going for a wider style, such as a European king or super king mattress.

Whether you sleep on your back, front, side or a mix of them, getting the right mattress firmness is important for supporting your back and relieving tension from your pressure points as you sleep. That's why at Dormeo, we have a wide range of mattresses including our popular memory foam, and S Plus collections available. We are so sure you'll find the perfect one to suit you that we even offer a 60-night comfort guarantee. This means you can test your new mattress out for up to 60 days and return it for a full refund if you decide it's not for you!