What Mattress Firmness Is Best? Mattress Firmness Guide

Buying a new mattress and boggled by all the talk of soft, medium, firm - or even H2, H3, and numbered scales? You’re not alone. With every brand using a different system, it can feel like you need a translator just to figure out what you're actually buying. And let’s be honest - most of us only start thinking about mattress firmness when the poor sleep, backaches, or endless tossing and turning start creeping in.

That’s why understanding what mattress firmness really means can make all the difference. In this guide, we’ll break down how firmness affects your comfort and posture, explain the firmness scale in simple terms and help you figure out which level is right for your sleep style.

What is Mattress Firmness?

Mattress firmness refers to how soft or firm a mattress feels when you first lie down on it. While comfort is highly subjective, firmness plays a crucial role in aligning your spine and supporting your sleep posture. A mattress that's too soft may allow your body to sink too deeply, while one that's too firm might not provide enough pressure relief. The difference in mattress firmness is caused by the use of different materials and their respective densities.

Understanding the Firmness Scale

In the UK, there’s no single standard for firmness ratings - some brands use terms like H2 or H3, others stick to soft, medium or firm, and some even invent their own systems. That’s why the 1–10 firmness scale is so helpful. It offers a general guide to how a mattress feels, even if the final choice depends on personal preference. Most experts agree that a score of 6.5 out of 10 is the sweet spot for medium firmness - ideal for a wide range of sleepers. Let’s take a closer look at what each level on the scale typically feels like in everyday terms.

Mattress Firmness Chart

Soft

• How does it feel? Soft mattresses offer a plush, cushioned feel that gently hugs your body. You’ll feel like you’re sinking into the bed, with the surface adapting closely to your shape - ideal if you like that “cloud-like” sensation.
• Who is it best for? Soft firmness levels tend to suit lighter individuals who don’t need as much pushback to stay supported. They’re also great for side sleepers, as the softness helps relieve pressure on the shoulders and hips.
• What’s it made of? Mattresses in this range usually feature thick comfort layers made from memory foam, quilted pillow tops or other soft foams. These materials are designed to enhance sinkage and contouring without feeling restrictive.

Medium

• How does it feel? Medium and Medium-firm mattresses strike a comfortable balance between softness and support. You’ll experience gentle contouring with enough firmness to keep your body lifted and well-aligned - no excessive sinkage, just a supportive 'give' under pressure points.
• Who is it best for? This firmness level is ideal for back and stomach sleepers, as well as side sleepers who prefer a slightly firmer feel. It’s also a great middle-ground option for average-weight individuals, combination sleepers, and couples with different comfort needs.
• What’s it made of? Medium-firm mattresses often combine soft upper layers with a more supportive core - typically high-density foam or pocket springs. This layered design offers a blend of comfort and stability, making it one of the most versatile firmness levels.

Firm

• How does it feel? Firm mattresses have a solid, supportive feel with minimal sinkage. You’ll stay fully on top of the surface, which creates a more stable, traditional sleeping experience - ideal for those who don’t like the sensation of sinking into their bed.
• Who is it best for? This firmness level suits stomach sleepers and heavier individuals who need extra support to maintain proper spinal alignment. It’s also a good choice if you prefer a sturdier surface that resists sagging and promotes better posture throughout the night.
• What’s it made of? Firm mattresses typically feature a dense core made of high-density foam or a robust spring system, with minimal cushioning on top. These materials are chosen for their ability to offer pushback and long-lasting support.

How to Choose the Right Firmness

Choosing the right mattress firmness depends on a mix of personal comfort, sleep position, and body type. The tips below will help you narrow down the best firmness level to support your sleep and overall well being.

• Identify your primary sleeping position: Side sleepers usually need something soft to cushion their joints, back sleepers tend to prefer medium-firmness for balanced support, and stomach sleepers require firmer surfaces to keep their hips aligned.
• Consider your body weight and shape: Heavier individuals often experience mattresses as softer than lighter sleepers do, so they may need a firmer option for proper support. In contrast, lighter sleepers interact mostly with the upper comfort layers and often do well with a softer feel.
• Think about your cushioning preference: If you prefer a mattress that gently cradles your body, lean toward softer models. If you’d rather feel lifted and supported, medium-firm to firm mattresses will likely suit you better.
• Factor in any physical discomfort: Those with joint pain or sensitive pressure areas may need plush top layers, while those with lower back pain might benefit from firmer, more supportive cores to maintain alignment.
• Account for shared sleep preferences: If you share your bed with a partner who has different sleeping habits or body type, opting for a medium-firm mattress can be a smart middle ground. According to Cloud9 experts, this firmness level is often best for couples who need to meet in the middle without compromising comfort or support.

Choosing the Right Degree of Firmness for Different Kinds of Sleepers

Even though firmness is a personal choice, understanding what suits your sleep position can help you make an informed choice.

• Back Sleepers: Back sleepers benefit most from medium-firm mattresses (around 6.5/10) that offer balanced support and comfort. This helps maintain spinal alignment and reduces lower back pressure.
• Side Sleepers: Side sleepers need softer mattresses (typically 4-6/10) to cushion pressure points like shoulders and hips. Zoned support can be especially helpful for comfort and spinal alignment.
• Stomach Sleepers: Stomach sleepers require firm mattresses (7/10 or higher) to prevent their hips from sinking and causing back strain. Lift and support are crucial to keep the spine in a neutral position.
• Combination Sleepers: Those who switch positions during the night should look for medium-firm mattresses that offer both mobility and comfort. A balanced feel supports all sleeping styles.

Choosing the Right Degree of Firmness for Different People

The ideal mattress firmness can vary depending on age, weight, and lifestyle. Here’s a quick guide to help match different sleepers with the firmness level that best supports their needs:

• Children: A medium-firm mattress is generally best for children, offering enough support for growing spines while still providing some comfort and cushioning.
• Teenagers: As teens experience growth spurts and shifting sleep patterns, a medium to medium-firm mattress can offer the balance they need for support and comfort through these changes.
• Lightweight Adults (up to 60 kg): Soft to medium firmness usually works well for lighter individuals, allowing them to experience proper contouring without feeling overly firm.
• Average-weight Adults (60-100 kg): A medium-firm mattress is often the most versatile choice, delivering enough support while still feeling comfortable for most sleep positions.
• Heavier Adults (over 100 kg): Firmer mattresses provide the support needed to maintain spinal alignment and prevent sagging, especially around the hips and lower back.
• Older Adults and Seniors: A medium mattress with pressure-relieving top layers can help ease joint discomfort while still providing the support needed for mobility and posture.
• People with Back Pain: A medium-firm to firm mattress is generally recommended to support spinal alignment and reduce strain on the lower back throughout the night.
• Couples with Different Sleep Preferences: A medium-firm mattress is often a reliable compromise, offering enough flexibility to cater to both individuals without sacrificing comfort or support.
• Pregnant Sleepers: Medium to medium-soft mattresses can provide pressure relief and gentle cushioning around the hips and bump, particularly for side sleeping in later stages of pregnancy.
• People with Joint or Pressure Point Pain: Soft to medium firmness is ideal here, as it helps reduce stress on sensitive areas like shoulders, hips, and knees while still offering enough structure.

Top Tips for Finding the Right Mattress Firmness

Here are some helpful tips to keep in mind during your mattress search:

• Don’t Confuse Firmness with Support: A soft mattress can still be highly supportive if it maintains spinal alignment, and a firm mattress isn’t necessarily better if it creates pressure points.
• When in Doubt, Go Medium-Firm: Medium-firm mattresses (typically around 6.5 out of 10) are often the safest starting point for most sleepers due to their balanced comfort and adaptability.
• Check Return Policies or Trial Periods: Firmness can feel different at home than it does in-store. Always look for a mattress with a risk-free trial period so you can test how it performs night after night.
• Avoid Ultra-Soft Without Reinforcement: Soft mattresses may feel luxurious at first, but without a solid foam or coil core, they can lose shape quickly and offer poor long-term support.

Now that you understand how mattress firmness works, you’re well equipped to make a confident, informed choice. From identifying your ideal sleep position to recognising how firmness affects support and comfort, you’ve got the key insights covered. With this knowledge, shopping for your next mattress should feel a lot less confusing - and a lot more tailored to your best night’s sleep.