How to Choose Mattress Firmness? A Guide for Healthy Sleep

Why is Mattress Firmness the Key to Healthy Sleep?

When choosing a new mattress, we often get lured by discounts or luxury covers, but the most important part is hidden inside. Mattress firmness (or stiffness) determines how well your spine will be supported during the night. The aim is clear: your spine must remain in its natural alignment, whether you sleep on your back or side.

Think of it this way:

• Too Soft a Mattress: Your body sinks in like in a "hammock". The muscles around your spine have to engage all night to keep it in the right position, leading to morning stiffness.
• Too Firm a Mattress: Your body cannot adapt. Pressure points develop in the shoulder and hip area, restricting blood circulation and forcing you to turn more often.

Firmness Scale: Do You Understand T1 to T5?

At Purtex and in the Czech market, you're most likely to encounter firmness labeled on a scale from 1 to 5 (sometimes marked as T1–T5 or H1–H5). How to read between the lines?

T1 and T2: Soft to Medium Soft Mattresses

These mattresses are like a cloud. They are the ideal choice for individuals with lower body weight (up to about 70 kg) and for those who primarily sleep on their side. Softer foam allows the shoulders and hips to sink deeper, aligning the spine.
Who is it for: Seniors (no pressure on joints), lightweight individuals, "side sleepers".

T3: Medium Firm Mattress (The Golden Mean)

Clearly the best-selling and most versatile option. How to choose mattress firmness if you're unsure? T3 is often a safe bet. It provides solid support but can still adapt to the body's curves due to its comfort layers.
Who is it for: Both women and men, teenagers, couples with similar body types. Suitable for sleeping on the back or side.

T4 and T5: Firm and Extra Firm Mattresses

Here, we're talking about a very firm base. These mattresses are designed for heavier loads or for individuals who require a firm bed for health reasons (e.g., as recommended by an orthopedist).
Who is it for: Individuals with higher body weight (over 100 kg), stomach sleepers, and those who prefer a firm bed feel.

For a more detailed explanation of individual levels, check out our glossary of terms: Firmness (stiffness) of Mattresses.

How to Choose Mattress Firmness: 3 Key Factors

There is no universal mattress for everyone. When choosing, follow this holy trinity:

1. Your Body Weight
   You cannot escape physics. The heavier you are, the more pressure you put on the mattress, and the firmer mattress you need to avoid sinking.
   Up to 70 kg: Choose softer options (T1–T2).
   70–100 kg: The ideal choice is medium (T3), or T4 for lovers of firmer sleeping.
   Over 100 kg: Look for T4 or T5 mattress firmness for long-lasting stability.
2. Sleeping Position
   This is where most people make mistakes.
   On your side: You need a softer mattress (T2–T3) that will yield in the shoulder and hip areas.
   On your back: The ideal is medium to higher firmness (T3–T4) which supports the lower back but allows the buttocks to sink slightly.
   On your stomach: Be careful here. You need a firmer mattress (T4) so that your lower back doesn't sag, which is very risky in this position.
3. Age and Health Condition
   With age, our preferences change. Seniors often prefer softer mattresses that do not put pressure on painful joints and do not restrict tissue circulation. Conversely, firmer mattresses are recommended for children and teenagers for proper spinal development.

Couple's Dilemma: He Wants Firm, She Wants Soft

A frequent scenario in the bedroom. The man weighs 100 kg and wants a "board", while the woman weighs 60 kg and wants a "cloud". Buying one large mattress 180x200 cm with the same firmness is a mistake in this case.

The solution is two separate mattresses within one cover, or partner mattresses with differing firmnesses on each side (e.g., one side T3, the other T4). This way, each sleeps on their own, but without a gap in the middle of the bed.

If you are still unsure and need a comprehensive guide, we recommend our article: 5 Steps to Choose the Right Mattress.

Quick Home Test for Proper Firmness

If you have the chance to test the mattress (or test your current one), lie on your back. Try to slide your palm under your lower back.

• If the palm goes in very difficultly: The mattress is too soft; you've sunk in.
• If there is a large gap: The mattress is too firm; it doesn't conform to your back.
• If your palm can slip in with slight resistance: Congratulations, you've found the ideal!

Ready for a change? Check out our wide selection of mattresses and choose the right one exactly according to your needs.

Frequently Asked Questions (FAQ)

What Mattress Firmness Should You Choose for Back Pain?

The myth that the hardest mattress is best for sore backs is false. If your lower back hurts, a hard mattress can be the cause, as it doesn't support the natural curvature of the spine. Usually, the best option is medium firmness (T3), which combines support with adaptability.

Does a New Mattress Soften Over Time?

Yes, every foam mattress will soften slightly over time. In the first weeks of use, a so-called "breaking in" of the materials occurs. So, if you're hesitating between two firmness levels, it's usually safer to choose the slightly firmer one.

What Does Mattress Zoning Mean and How Does It Relate to Firmness?

Quality mattresses have different hardness zones (e.g., 5 or 7 zones). This means that the mattress is firmer under the head and feet, while softer under the shoulders and hips, allowing these wider body parts to sink in. This increases ergonomic comfort.

How to Choose Mattress Firmness for a Child?

For children, medium-firm to firm mattresses (T3–T4) are generally recommended. A child's spine is developing and needs firm support, not soft sagging. Avoid zoned mattresses for small children who have not yet grown into the zones.