The Plank Firm Luxe might be the cure for my terrible posture — but one type of sleeper should skip this mattress

Can a luxurious plank be a real contender for the best mattress you can buy online? That's the aim of the Plank Firm Luxe mattress, a double-sided hybrid bed with a super firm feel that promises to deliver non-stop support for your spine. I put it through our rigorous mattress testing methodology, to see how it performed.

I previously tested the original all-foam Plank Firm mattress and as a stomach sleeper, the stable support transformed my sleep. The Plank Firm Luxe mattress takes everything I loved about the Firm — even support, fantastic motion isolation, strong edges — and adds springs.

This hybrid build gives the Plank Firm Luxe mattress a more responsive feel. As a result, it's a bit more luxurious. It also turns the pressure relief up a tiny notch. With the springs responding to your movement, there's a bit more body contouring.

However, the Plank Firm Luxe is going to be a divisive mattress. For most side sleepers, it's a hard 'no' (and hard is the operative word). But when it comes to support, the Plank Firm Luxe shines. After sleeping on a queen size for over a month, and subjecting it to a series of tests in our Sleep Lab, here's my full review.

Plank Firm Luxe Mattress review: Price & trial

• Plank typically offers 25% off the Firm Luxe, although that can rise to 30% during major sales events
• In the year-round sale, a queen is $1,198.50 (from an MSRP of $1,598), xxx
• A 120-night trial and limited lifetime warranty is included

The Plank Firm Luxe mattress is an upper mid-range bed: it's an investment but not a premium purchase. A queen has an MSRP of $1,598 but frankly, you're never going to pay that much. A year-round 25% off mattress sale reduces a queen to $1,198.50.

Here's what you can expect to pay for a Plank Luxe mattress:

• Twin MSRP: $1,065 (normally sold at $798.75)
• Twin XL MSRP: $1,198 (normally sold at $898.50)
• Full MSRP: $1,465 (normally sold at $1,098.75)
• Queen MSRP: $1,598 (normally sold at $1,198.50)
• King MSRP: $1,865 (normally sold at $1,398.75)
• Cal king, RV king MSRP: $1,865 (normally sold at $1,398.75)

That places it in a similar price bracket to the Helix Core mattress collection — a queen Helix Dawn Mattress is $1,183 in the 20% off sale ($1,478.75 MSRP). The Dawn is another hybrid bed with a firm feel that's designed for stomach and back sleepers, although it lacks the double-sided build of the Plank Luxe.

But when it comes to competitors, it's hard to find a decent rival for the Plank Firm Luxe — there are few flippable, super-firm hybrids out there. The original Plank is the best comparison and it's $999 for a queen in the sale. However, it's an all-foam design (and the best memory foam mattresses tend to be cheaper than their hybrid equivalents).

If it's only firmness you want, there are more affordable options available. For example, the Siena Signature is a firm bed and only $294 for a queen. But it probably lacks the durability of the Plank.

In terms of extras, a 120-night sleep trial is included, which should be more than enough time to adjust to the mattress. However, considering it's a double-sided bed — and as Extra Firm mattresses can take some time to get used to — I'd hoped for a longer trial. For example, rival DreamCloud offers a 365-night testing period.

Plank also offer a limited lifetime warranty. This is comparable to the best in the industry. Based on the warranty, quality of materials and design, we predict a good mattress lifespan of 6 to 10 years.

Value for money score: 4

Plank Firm Luxe (twin): was $1,065 now $798.75 at Plank Mattress

A Plank Firm Luxe mattress is typically $1,198.50 for a queen in the year-round 25% off sale at Plank, reduced from $1,598. If you want to save more, it's worth waiting for a 30% off deal — these typically appear around the major sales days. A 120-night trial and limited lifetime warranty are included.

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Plank Firm Luxe Mattress review: Design & materials

• The Plank Firm Luxe is a 12" double-sided hybrid mattress.
• Firm on one side, Extra Firm on the other, with a layer of springs in the middle
• However, there's no handles, which makes flipping difficult

The Plank Firm Luxe mattress is made of springs and foams, but its design is unusual for a boxed mattress. For a start, the spring layer sits in the center of the bed.

This is unusual — the best hybrid mattresses typically use springs at the base of the design, to provide support. But the Plank Firm Luxe is atypical and the spring core is crucial to its double-sided design.

On one side of the springs, you'll find the Firm side. This is a 2" layer of high density support foam, followed by 1" comfort foam, topped with a 1.5" quilted top.

On the other side of the springs is the Extra Firm side. Again, you'll find a 2" layer of high density support foam but in this case, it's only topped by 0.75" of quilted top.

That missing 0.75" of foam is in service of the double-firmness design. Even the quilting makes a difference in the feel; the Extra Firm side has a continuous stitch to create a flat surface, while the track-and-jump Firm side adds a bit more padding.

There's one frustrating flaw with the design, however — no handles. Considering this bed is designed to be flipped, it's annoying that you don't have anything to hold onto.

Plank Firm Luxe Mattress review: Sleep comfort

The original Plank Firm was the bed that made me fall in love with firm mattresses. So I was excited to get my hands on the Luxe, which promises to take all the benefits of the all-foam Plank and add a touch more luxury.

Within a night, I could tell the Luxe was going to deliver the same exceptional support. It's firm from head-to-toe, with no give at the hips. This keeps the body lifted and aligned, preventing strain on the lower back. As a stomach sleeper, it's just what I want. Our back sleeping testers were also pleased with the solid, stable, full-body support.

But side sleepers are going to struggle with the lack of cushioning. One of our testers is a lightweight side sleeper and she couldn't get comfortable on the Plank Firm Luxe. Also, the lack of handles is a strange oversight; when Frances and I tried to flip the bed, I almost got knocked out.

Comfort is subjective, however, and an unusual bed like the Plank Firm Luxe is never going to please everybody. So I conducted a series of objective lab tests to assess every side of the Luxe. Here's why it measures up as one of the best firm mattresses you can buy.

Temperature control: 3.56 out of 5

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Temperature regulation refers to how well a mattress is able to maintain an even feel throughout the night. A mattress with good temperature regulation dissipates excess heat, keeping you around 65 to 70°F/18 to 21°C (the perfect temperature for sleeping). A bed that struggles with temperature control often gets uncomfortably warm during the night.

We use a thermal cam to objectively test temperature regulation. First, one of our testers rests on the bed for 15 minutes. During this period, we measure the temperature of the mattress every minute, to see how much it heats up. This gives us the maximum temperature increase, or MTI.

On the Firm side, we recorded an MTI of 15.1°F. That's one of the biggest jumps we've seen, even higher than the 12.4°F of the Helix Sunset Luxe mattress. In comparison the Saatva Classic, our top-rated bed, gained just 6.3°F.

On the Extra Firm side, the increase was less significant but pretty high — we recorded an MTI of 14.3°F. This is still a disappointing result but indicates the Extra Firm side absorbs less warmth than the Firm side.

An increased MTI doesn't necessarily mean a bed will sleep exceptionally hot, however. The Bear Elite Hybrid is the best cooling mattress we've tested and it had an MTI of 10.5°F. Which brings us to the next part of our test — the cool down.

After 15 minutes, our tester gets off the mattress and we continue to monitor the temperature for another 15 minutes. This provides the cooling rate.

The Firm side of the Plank dropped relatively quickly, losing 7.1°F in the first 5 minutes. This creates a rapid cooling rate of 1.46°F/minute, faster than the Saatva Classic's 1.26°F/m. However, the Saatva Classic did have less heat to lose in the first place.

The Extra Firm side showed a faster temperature drop off, with a rapid cooling rate of 2.2°F/min. This is impressive, beating even the Bear Elite Hybrid's rapid cooling of 2.06°F/m.

These results suggest that the Plank Firm Luxe warms up quickly. We unboxed the Plank Firm alongside the SweetNight CoolNest mattress and tester Frances noted that the SweetNight felt significantly cooler than the Plank, even under identical testing conditions. However, once you get off the mattress, it should dissipate heat relatively quickly.

During my subjective testing, I slept comfortably on the Plank Firm Luxe, even during several heatwaves. However, I did find the Extra Firm side stayed cooler than the Firm side. This is likely because the Firm side has more foams, which can trap more heat.

Plank does offer a cooling upgrade; a GlacioTex cooling cover. For hot sleepers, I think this is a worthwhile addition. I've tested a memory foam pillow with a GlacioTex cover and this cool-to-the-touch material should help offset the heat build-up of the Plank Luxe. Alternatively, the Bear Elite Hybrid does come in a firm feel and sleeps comfortably cool.

Pressure relief: 3.8 out of 5

When you lie on a mattress, your body presses against the bed. A mattress with good pressure relief will cradle these touch points to evenly distribute weight, while supporting the body to prevent the spine from sagging. This reduces pressure build-up so you wake up without aches and pains.

Before we dive into the pressure relief of the Plank Firm Luxe, it's worth noting that this mattress isn't designed to offer much cushioning. It's all about the support. If you want contouring, you're better off with a bed like the Saatva Classic or the Helix Midnight Luxe.

We use a 25kg weight (roughly one-third the weight of the average American) to objectively determine pressure relief. We place the weight in the hip and shoulder area, using a laser to measure how much it sinks. We measure again after 5 minutes. Once the weight is removed, we time how quickly the materials bounce back.

On the Firm side, the weight sank 3.1" at the hip and 3.25" at the shoulder. On the Extra Firm side, the weight surprised us by sinking fractionally further; 3.25" and 3.375", respectively. That's a fairly minimal difference and can possibly be chalked up to the padded top of the Firm side lifting the weight in certain places. Overall, that's an average sink of 3.18" for the Firm side, 3.31" on the Extra Firm side — or 3.25" overall.

That's firmer than most beds we've tested. The Siena Signature, an all-foam bed with minimal cushioning, had an average sink of 3.625". However, the Nectar Classic Memory Foam mattress has an overall sink of 2.875". So that might be the stronger choice if you don't want any contouring at all.

When we removed the weight from the mattress, the surface bounced back almost immediately. This fast recovery time makes it easy to change positions. And it means if you do toss and turn, the surface quickly springs back to shape to keep you supported.

Our hands-on testers agreed that this bed prioritizes support over cushioning. Side sleepers Frances Daniels felt significant pressure build-up on both the Firm and Extra Firm sides, particularly at her shoulders and hips.

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During my at-home testing period, I was impressed by the support offered by both sides of the mattress. I'm a stomach sleeper and softer beds often put strain on my lower back. The Plank Firm Luxe kept my spine lifted and straight, alleviating any aches and pains. This puts it among the best mattresses for stomach sleepers and it's a benefit for back sleeping.

As a sometimes side sleeper, I did experience the occasional 'dead arm' on the Extra Firm side. This is less of a problem on the Firm side, as the added layer of foams delivers some cushioning.

But for dedicated side sleepers seeking support, I recommend the Saatva Classic. It simply has a better blend of cushioning and support. Although if you want a bed that holds your spine lifted all night long, the Plank Firm Luxe is an excellent choice.

I've previously slept on the Plank Firm, the all-foam version of the Luxe. Overall, the foam version had slightly less sink and a slightly faster recovery time. The more responsive Luxe delivers a touch more contouring, which means slightly better pressure relief, without losing any of that support.

Firmness

Mattress firmness is measured on a scale of 1 to 10. 1 indicates marshmallow soft, while 10 is rock hard. No surprise, all our testing team placed the Plank Firm Luxe mattress at the higher end of the scale.

Plank rates the Firm side as an 8 out of 10, or firm. We agree with that rating. Plank gives the Extra Firm side a mighty 10, which is the firmest you can get. We place it slightly under that, with a 9 — still exceptionally firm but with some slight contouring at the touch points.

The best mattresses for back pain often have a firm feel, to keep the spine lifted. I love how the Plank Firm Luxe straightens out my back. I have a tendency to 'shrimp' when I sit at my desk but lying on the Plank Luxe feels like I'm offsetting my terrible work posture.

It does somewhat live up to its namesake wooden plank but the addition of springs gives the bed a touch of body contouring. However, if you like to feel cushioned as you sleep, a hybrid with a plush Eurotop layer, such as the Saatva Classic, is a better choice.

Motion isolation: 3.75 out of 5

Good motion isolation stops movement from traveling across the mattress. It means if your partner tosses and turns, or your cat jumps on the bed, the movement won't bother you.

We use a drop test to objectively test motion isolation. Placing an accelerometer on one side of the mattress, we drop a 5kg slam ball on the other side. We then measure the force of the drop on the mattress (the initial impact absorption or IIA) and how long it takes the movement to come to an end (the decay rate).

I was blown away by the motion isolation of the all-foam Plank Firm but I wasn't expecting as much from the Luxe — the addition of springs tends to add bounce. However, both sides impressed. The Firm side had an initial impact of 4.47 m/s2, while the Extra Firm stunned with just a 3.8 m/s2 IIA. That's an average of 4.14 m/s2.

That means even if you jump onto the Plank Luxe, the mattress will absorb much of the movement straight away. In comparison, the Siena Mattress had a best in class IIA of 5.527 m/s2.

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But while the initial impact absorption of the Plank Luxe impressed, the decay rate told a different story. We recorded an average decay rate of 3.632 seconds on the Firm side, 3.428 on the Extra Firm, for an overall of 3.53 seconds. That's slow. The Saatva Classic stopped all motion in just 1.703 seconds on average.

This result is reflected in our hands-on testing. As Frances described, there is some "wobble", particularly on the Extra Firm side. As a deep sleeper, I think the disruption is minimal and I could sleep through all but the heaviest of movements (I hardly felt Frances getting on and off the bed). However, light sleepers might find their rest disrupted by the occasional shudder.

Edge support: 4.5 out of 5

Perch on the side of your mattress and you'll appreciate the benefit of good edge support — this is what keeps you stable when you sit on the perimeter. It's particularly useful for those with limited mobility, who like to push against the mattress when getting in and out of bed.

We break out the 25kg weight to test edge support. Placing it 3" from the side and foot of the bed, we use a laser to measure how far the weight sinks. At the foot of the bed, the weight sank 3.625" on both the Firm and Extra Firm side. On the side of the bed, we measured a sink of 3.125" on the Firm feel, 3.375" on the Extra Firm (that's an average of 3.25").

This is among the best we've seen. It's comparable to the edge support of the Siena (which sank just 3.06" at the foot and 3.125" at the edge of the bed).

Our testers all felt comfortable sitting on the side of the bed. But for a true test, I asked my mom (and her dodgy knee) to try the Plank Luxe mattress. She noted there was some slight dipping but said she'd feel happy getting on and off the mattress, even at 3 a.m. when her joints are feeling rusty.

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Edge support isn't just about sitting. Strong edges allow you to use the entire surface of the mattress, making it a useful feature for couples. To measure this, we use a roll off test. Yes, it's what it sounds like — we keep shuffling towards the edge until we roll off the bed.

We found you could stretch out all the way across the mattress. I was dangling off before gravity took over. If your partner likes to starfish, you won't roll off as you cling to the edge.

Plank Firm Luxe Mattress review: User reviews

The Plank Firm Luxe has an average of 4.6/5 stars from a total of 3,200+ user reviews. Many of the positive reviews praise the impact of reliable firm support on back pain, with one reviewer noting that since switching to the Plank Firm Luxe they wake up without back pain for "the first time in five years".

A few reviews note that the Plank Firm Luxe isn't as firm as they were expecting. One reviewer complains that it's not as firm as their tatami mat (a thin mat often placed on the floor). Firmness is subjective and while the Plank Luxe is hard, it's not going to be as hard as lying on the floor.

Alternatively, a few reviewers complain it's too firm — this is where the 120-night trial has its benefits. If you underestimated just how firm the Plank is, you should be able to return it for a refund.

Plank Firm Luxe Mattress review: Should you buy it?

If you're looking for full-body support in a mattress, the Plank Firm Luxe takes some beating. It's firm from corner to corner and edge to edge, ensuring every part of your body if held aloft. For stomach and back sleepers, that means no more pressure on your lower back.

The double-sided design is an unusual feature but it's not a gimmick. While the Extra Firm side comes out on top when it comes to full body support, the Firm side is better when you want more cushioning. It's a shame that a lack of handles makes flipping between the two a chore.

While support is the focus, the Plank Firm Luxe hasn't skimped on other features (well, maybe some pressure relief — I'll get to that later). The edge support is superb (4.5/5) while the motion isolation is strong (3.76/5). It's not a cooling bed but I stayed a relatively neutral temperature even during a hot summer and the GlacioTex cover upgrade is available for very hot sleepers.

With these factors in mind, it's among the best mattresses in a box we've tested. However, there's one demographic that should swerve this one: side sleepers. The Plank Firm Luxe features almost no cushioning at the shoulders and hips. As a result, if I rolled onto my side, I woke up with a numb arm and a dead hip. A traditional hybrid like the Saatva Classic will provide similar support and much better pressure relief.

In the standard sale, a queen is $1,198 ($1,598 MSRP). That's a good price for a specialist mattress. However, the Plank Firm is $999 in the same sale ($1,332 MSRP). For everyone but hot sleepers, I think it's worth saving your money. For hot sleepers, pay the extra; the Luxe sleeps much cooler.

Alternatives to consider