Not a typo! This firm king mattress is $509 at Amazon now

Navy and white Serta Sleeptrue firm hybrid mattress with a cartoon sheep, floral pillow and navy pillow on top

(Image credit: Amazon)

Firm mattresses offer a supportive sleep surface that you lay on top of rather than sink into. And they are particularly good for back and stomach sleepers, and anyone with a heavier body weight. We've found a fantastic deal, not just on a firm mattress, but on a king size so you can treat yourself to some extra space. Right now, you can save $90 on a king size Serta Sleeptrue Firm 11" Hybrid mattress at Amazon, bringing the price to just $509.15 (was $599).

Our best mattress picks of the year come with exceptional comfort, support and value for money, but rarely do we see a top-performing king size mattress drop this low in price. The Serta combines a custom Support Coil System with cooling gel memory for a comfortable night's sleep. This memory foam is structured into 3 zoned areas for maximum back support, making it a great choice for sleepers with back pain.

Third-party retailers often offer great value during major sale events like the current Cyber Monday mattress deals, and we've shopped around for the best value you can get. You won't find this mattress anywhere cheaper than Amazon right now. Here's why it's a great deal...

Serta Sleeptrue Firm 11" King Hybrid mattress
Was: $599
Now: $509.15
Saving: $89.85 at Amazon

Mattress summary: Although its an affordable mattress in a box, the Serta Sleeptrue Hybrid mattress has quality features including triple-zoned support, cooling technology and pressure relief. The three zones take care of supporting your back no matter how tall you are. Meanwhile, gel memory foam enhances heat dissipation and pressure point cradling while 800 individually wrapped coils improve airflow and durability. At 11" tall it is thick enough to suit most adult bodies, no matter your sleep positions. With 15% off in the Cyber Monday sales, a king size is now $509.15 (was $599). A king is the only size on sale right now, but we recommend you take advantage of this deal if you have the space to upgrade to a king mattress.

Price history: At MSRP, the Serta Sleeptrue Firm Hybrid is priced in line with the best cheap mattresses of the year making this Amazon discount extra sweet. It isn't discounted on the manufacturer's website at the moment and is $539.10 at Best Buy. So, this Amazon deal is the one to bag. Plus, you're unlikely to find another king size mattress for such a low price.

Benefits: Free shipping | 100-night trial | 10-year limited warranty

Looking for something more premium? Try this...

The WinkBed mattress: was from $1,149 $849 at WinkBed
The upper-mid-range WinkBed mattress is our best mattress for heavy people and one of our best firm mattresses of the year. It comes in four different firmness options (soft, luxury firm, firmer, plus) and is handmade to order in the USA. We recommend it to people with back pain and heavy bodies looking for a supportive sleep surface. There is $300 off the WinkBed right now, no matter the size or firmness. This offer brings a queen size luxury firm to $1,499 (was $1,799), or you can level up to a king for an extra $200.

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Eve is a PPA-accredited journalist with an MA in Magazine Journalism from Cardiff University. She is a Sleep Staff Writer at Tom’s Guide and has four years’ experience writing health features and news. She is particularly interested in the relationship between good sleep and overall health. At Tom’s Guide Eve is responsible for coverage and reviews of sleep tech and is our smart and cooling mattress specialist, focussing on brands such as Eight Sleep and Sleep Number. She also covers general mattress reviews, seeks out the best deals to produce tried-and-tested buyer's guides for sleep accessories and enjoys writing in-depth features about sleep health. She has been involved in rigorous testing procedures for mattress reviews in our Sleep Studio and has interviewed experts including sleep doctors and psychologists. When not covering sleep at Tom's Guide, Eve enjoys writing about health and fitness, food and culture.