Plank Firm mattress review 2024

Plank Firm Mattress review in brief

The Plank Firm Mattress is a dual-sided mattress designed to be the firmest and flattest on the market. Described as 10 out of 10 on the firmness scale (for context, that's as hard as a board), we wanted to know if the Plank Firm Mattress sacrificed comfort for support and could truly live up to its ultra-firm promises.

We tested a full size Plank Firm for over a month, spending more than three weeks on the Extra Firm side and two weeks on the Firm side. Below, we'll give a full breakdown of both sides of the Plank Firm, but if you're short on time, here are the highlights.

Most of the mattresses we test for our best mattress guide go for a crowd-pleasing medium firmness, but the Plank isn't afraid of the extremes. Yes, it is super firm and very flat. There's almost no contouring to the Extra Firm side (and the Firm side isn't much softer) meaning most side sleepers are likely to wake up with aching arms and hips.

However, the support is exceptional, from head-to-toe and edge-to-edge. Every member of our testing panel felt supported when back sleeping, and our stomach sleeping lead tester never woke up with lower back pain. We also felt comfortable side sleeping on the Firm side, although lightweight sleepers will need more cushioning.

There are some minor nitpicks. As a double-sided mattress, it really needs a set of handles to help you flip it over. Flipping a mattress is already a difficult task, and while the Plank Firm doesn't have an unwieldy build, a lack of handles makes changing sides that bit more difficult.

The temperature regulation could also be improved, as our lead tester woke up warm on several mornings. However, very hot sleepers do have the option of upgrading to the cooling GlacioTex cover. And while the dense foams trap some heat, they also absorb all movement; you'll hardly feel your partner move around in the night.

The mid-range price tag is competitive for a specialist mattress, especially with an evergreen sale knocking 20% off the MSRP. And as a double-sided, very firm mattress, there's not much else like the Plank Firm Mattress out there. But it's the features that make it unique also make it divisive – some of you are going to love it, and some will hate it.

Plank Firm Mattress review: price & trial

• Regular mattress sales take 20-25% off
• A queen typically sells for $999 ($1,332 MSRP)
• Comes with a 120-night trial and a 10-year warranty

The Plank Firm Mattress is always discounted, with a 20% off mattress sale running for most of the year. This reduces a queen size to $999 (from an MSRP of $1,332) and places the Plank Firm in the mid-range price bracket.

Below is the current MSRP and sale price for the Plank Firm Mattress:

• Twin MSRP: $749 (normally sold at $561.75)
• Twin XL MSRP: $849 (normally sold at $636.75)
• Full/short full MSRP: $999 (normally sold at $749.25)
• Queen/short queen MSRP: $1,332 (normally sold at $999)
• Olympic queen MSRP: $1,532 (normally sold at $1,149)
• King/Cal king/short king/ RV king MSRP: $1,532 (normally sold at $1,149)

With the evergreen discount, the Plank Firm is a competitor of the Helix Midnight Mattress and Nectar Premier Mattress. We rate these two beds highly, although they have very different feels to the Plank (check out our Helix Midnight Mattress review and Nectar Premier Hybrid Mattress review for more details).

Plank often increases the discount over the major holidays, including the Black Friday mattress sales. On these occasions, the discount jumps to 30% off. This is the best time to buy – we've never seen 30% off bettered. However, if you don't want to wait for a saving, the evergreen pricing is competitive for a mattress with a specialist USP.

Plank offers a 10-year warranty, which is aligned with the industry average. The 120-night sleep trial is slightly better than the standard 100-night trial and should provide ample time to test both sides of the mattress (although for such a divisive design, we might have hoped for a slightly longer trial).

Plank Firm Mattress: from $749 $561.75 at Plank
The evergreen Plank sale offers 20% off every size, reducing a queen to $999 from $1,332 (without the cooling cover upgrade). If you don't need a new bed urgently, you might want to wait around for the 30% off sale to return, but the current deal is a good price and you are (almost) getting two mattresses in one.

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Plank Firm Mattress review: Design

• A dual-sided mattress with a Firm and Extra Firm side
• Six inches of high-density foam provides the support and feel
• Firm side features additional two inches of contouring foam

Bear with us, because it's going to take a moment to break down the complex design of the Plank Firm Mattress. That's because there are two sleep surfaces to the Plank Firm, allowing you to flip the mattress to choose the feel you want (although whichever way you have it, it's going to feel firm).

Plank has created this dual design by building from the center out. In the middle of the Firm Mattress is a 6" layer of high-density foam which provides the support for both sides of the mattress. This foam has very little yield – you lie on top of it, and you don't sink in.

Flip to the Extra Firm side and the interior foam core is topped with a 0.75" quilted top... and that's it. On this side, you're mostly feeling the support foam. A continuous pattern quilted design keeps the top flat, for minimal lift and only the slightest cushioning.

Switch the mattress to the Firm side, and an additional two inches of comfort foam sit between you and the dense support core. This is what gives the Firm side that extra bit of softness, providing more pressure relief to the touch points.

Like the Extra Firm side, the Firm side also has a 0.75" quilted cover, although the looser track-and-jump quilt pattern gives it added cushioning. It's still not the sumptuous padding of other quilted designs, but there's more lift than the Extra Firm Side.

If you prefer a bouncier feel, you can upgrade to the Plank Luxe Mattress. This is a hybrid mattress, and the addition of coils is likely to give it a bouncier feel with more responsive support, which is what we expect from the best hybrid mattresses we've tested. But don't worry, it's still very firm.

Plank Firm Mattress review: Comfort & support

• An incredibly firm mattress, you'll lie on top of it
• Extra Firm side is 9/10 on the firmness scale, best for back sleeping
• Firm side is 8/10, suits stomach sleepers and some side sleepers

Plank describes its Plank Firm as the "firmest, flattest" mattress around and from our experience, that rings true. Every member of our testing panel had the same reaction when first trying the Extra Firm side, which could be summed up as: "Wow, that's firm."

Despite being made entirely of foam, the Plank Firm lacks the cushioning you'd expect from the best memory foam mattresses. Particularly on the Extra Firm side – there's no sink, and even at the touch points your body feels held up. After a breaking-in period, the Extra Firm side did soften up slightly, but only slightly.

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Plank describes the Extra Firm side as 10 out of 10 on the firmness scale (with one indicating soft and 10 as firm as the floor). Our team agreed on nine out of 10 as there is some yield, especially once you've gotten past the initial surprise of the hard feel.

Our lead tester is a stomach sleeper and appreciated the exceptional support the Extra Firm feel gives to the hips. The best mattresses for stomach sleepers tend to have a firmer finish, and the Plank Firm held the spine straight throughout the night. However, there is one issue with stomach sleeping: if you eat before bed, the mattress pushes against the belly.

All of our testers found back sleeping the most comfortable position on the Extra Firm side, with several even gravitating towards their back, despite it not being their usual sleeping position. Our tester with back pain also felt the Plank Firm would help limit aches, thanks to the flat surface supporting the entire lumbar region.

Side sleeping, however, is uncomfortable. Your hip and shoulder press into the bed when side sleeping, which is why the best mattresses for side sleepers have ample cushioning. The Extra Firm Plank, on the other hand, has almost none. When our lead tester slept on her side she woke up with a numb arm.

To measure pressure relief, we placed a 35lbs weight in the center of the mattress. On the Extra Firm side, it sank just 1.5", indicating limited pressure relief.

Score: 4 out of 5 (for stomach and back sleeping)
Score: 3 out of 5 (for side sleeping)

The Firm side is more of a crowd-pleaser. Plank rates it eight out of 10 for firmness and our testing panel agreed. The added layer of foam increases cushioning, which also means better relief for side sleepers – the weight sank 2.5" here. Our lead tester could sleep on her stomach or side and still wake up comfortably. The Firm side should also appeal to back sleepers.

But it's worth noting that for some, the Plank will be too hard regardless of sleep position. Greater pressure relief is a must for most side sleepers, but the Plank also lacks the 'coziness' you might expect from a softer or even medium-firm mattress.

There's another aspect of comfort to consider here: the dual-sides. We tested each side of the mattress for several weeks, flipping between them just once. Some double-sided mattresses suffer from a lack of difference – no matter what side you use, it feels the same – but this isn't an issue with the Plank. The Extra Firm side is notably harder than the Firm side.

We could see the double-sided nature being useful for those with a reoccurring injury, who might have changing comfort needs. However, for the most part, you're likely to find yourself favoring one side over the other (our lead tester certainly did).

Plank Firm Mattress review: Delivery & setup

• Easy to set up (and you can't get it the wrong way round)
• Limited off-gassing that dissipates quickly
• As a flippable mattress, it could use some handles

Like all the best mattress in a box, the Plank Firm is vacuum packed, rolled, boxed, and delivered to your doorstep. Shipping is fast and free, but there's no option for white glove delivery.

Our box was damaged when it arrived, but this is likely to have happened during the shipping process (and it had further to travel than most). Inside the box the mattress was undamaged.

There was a mild off-gassing smell to the Plank Firm but this dissipated quickly. The box, however, had a terrible smell. Again, this might be the result of the shipping process but you should probably unbox the Plank as quickly as possible.

Unpacking the Plank Firm Mattress was easy, especially as you can't put the dual-sided design the wrong way round (a common mattress unboxing mistake). Plank recommends leaving the mattress for three to five hours before sleeping on it, to give it a chance to expand. Our model quickly sprung into its full shape.

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But unlike many mattresses, the setup doesn't end when the Plank Firm is on the bed frame. As a double-sided mattress, you're going to want to flip it occasionally.

Our lead tester was able to flip her full-size Plank Mattress without any help, but it would be easier with two people. This is a mattress that could really benefit from a set of handles. Without them, it's tricky to move the mattress from one side (feel) to the other.

One minor nitpick is that there's no labeling to show which side of the mattress is which. If it's your first time using the bed, you might have to flip back and forth until you can figure it out. (A quick tip – if the word 'Plank' is the right way up, you're on the Extra Firm side.)

Setup score: 4 out of 5

Plank Firm Mattress review: Performance

• Impressive motion isolation on either side
• Strong on the edges and corners
• Could sleep warm (cooling upgrade available)

We tested the Plank Firm Mattress for more than six weeks, starting with the Extra Firm side before switching to the Firm side. We placed it on a slatted bed frame dressed with breathable covers. 

As part of our mattress testing methodology, we tested for several key areas of performance, including motion isolation, edge support, and temperature control. Here's what we found...

Motion isolation

The Plank Firm has a deadened feel; there's no bounce but there's no sink either. This gives it excellent motion isolation. When one person climbs into bed, the surface hardly moves at all.

The Extra Firm side comes out on top here and if you want to stop motion transfer, stick with this feel. The slight cushioning of the Firm side means it has a bit more bounce, but either way, we rate the motion isolation highly.

Our lead tester sleeps alone, but our testing panel did dutifully climb in and out of the bed to test the motion isolation. For an objective test, we placed a wine glass on the bed and dropped an 18lb weight onto the mattress from a height of 4".

We dropped the weight from 25", 12", and 4" away from the wine glass. At 25", the glass stood still on both the Firm and Extra Firm side. From 12", the glass wobbled slightly on the Firm side but stood still on the Extra Firm side. From 4" inches, the glass fell on the Firm side but stayed upright on the Extra Firm side.

Score: 4.5 out of 5

Temperature control

We expected the Plank Firm to have good temperature regulation, as the lack of sink tends to leave more room for air to circulate. However, despite testing the Plank Firm during a cool winter in the UK, it still got warm.

This wasn't a major issue – our lead tester never woke up from the heat – but she was sometimes enthusiastic to kick off her covers when the alarm rang. And if you regularly experience night sweats or overheating, you might feel uncomfortable in the morning.

Hot sleepers should consider upgrading to the GlacioTex cover. GlacioTex material is used in several of our best cooling mattress picks and has a cool-to-the-touch feel and a slicker surface. This upgrade will add roughly $100 - $150 to the overall price.

Score: 3.5 out of 5

Edge support

Edge support refers to how sturdy the mattress is around the perimeter, and it tends to be weaker on all-foam mattresses. Not so here. The Plank Firm is strong right up to the corners.

Our testing panel were impressed with the edge support, finding they could sit or lie on the side without risking collapse. One of our testers highlighted the support at the sides as their favorite feature of the mattress.

To back up our subjective tests, we used a weight to take an objective measurement. We placed a 35lb weight on the corner and side of the mattress and measured how much it sank.

On the Extra Firm feel, the weight sank just 1" at the side and 1.5" at the corner. On the Firm side, it sank 2" at the edge and 2.5" at the corner. This is similar to the sinkage we measured at the center and, once again, indicates excellent edge support.

Score: 5 out of 5

Plank Firm Mattress review: User reviews

• Rated 4.7 out of 5 stars from over, 3,400 reviews
• Reviewers praise the support and strong edges
• Unsurprisingly, the Extra Firm feel is divisive

There are 3,484 reviews of the Plank Firm on the Plank website, of which 2,813 of them are five stars. Positive reviews praise the support of the Plank Firm, with many customers finding it provides sufficient firmness without the unyielding feel of some firm mattresses.

There are some criticisms. Several customers complain about waking up hot, which matches our experience. Some customers also have issues with the firmness, although here it can go either way. By this, we mean that while some find the mattress too firm, others find it too... soft?

Firmness is famously subjective, and after you've broken in the Plank Firm you can feel some cushioning (even on the Extra Firm side). If you want no softness whatsoever, consider a Japanese floor mattress.

Should you buy the Plank Firm Mattress?

The Plank Firm Mattress seems like an acquired taste, but our testers were surprised by how much they liked this bed. The Extra Firm feel can be a surprise at first but once you've gotten past that initial hardness, the support shines.

The Firm side has a wider appeal, with an added layer of cushioning helping to offset the hardness. For stomach sleepers, the Firm feel is fantastic, maintaining support across the back without pressure build-up at the hips.

Support really is the star of the Plank Firm, and you can feel the benefit all the way across the mattress. You can sit or lie on any corner or side and never worry you're going to slide off. And because it supports up to 950lbs of weight we recommend this as one of the best mattresses for heavy people that we've tested.

The flip side of this is pressure relief. For back or stomach sleepers, there's enough relief on either side to get comfortable. For side sleepers, the Plank Firm can feel uncomfortably hard. Even on the 'softer' Firm side, there's limited cushioning.

And speaking of flipsides: is the double-sided nature of the Plank Firm more than just a gimmick? Our testing panel found there was enough difference between the two sides that they would consider flipping it from time to time, even if they would have appreciated some handles. But with both surfaces very hard, there are many sleepers the Plank Firm won't appeal to at all – no matter how you flip it.

Plank Firm Mattress review: Also consider