A split king is the configuration most couples actually want and the one most often skipped at checkout. Here is what it needs, what it costs, and the specifications to judge a Costco bundle against.
Retailer stock rotates by week, warehouse and region, so we do not claim any particular model is on the shelf today. The bases below are the ones we have reviewed: use their specs, capacities and warranties as the benchmark to hold a retailer SKU against before you buy.
Research evaluation. We have not run adjustable bases through a physical lab protocol, so there are no measured noise, durability or motion figures on this page. Ratings are editorial, based on published specifications, warranties, policies and owner feedback.
Two twin XL mattresses, one per deck. A single king mattress bridging both sides cannot flex independently and will be stressed along its centre.
Two twin XL fitted sheets plus a king flat sheet or duvet on top. That combination is what a 'split king sheet set' contains.
Independent sides need independent control. Check whether the bundle ships two remotes or a single remote with partner sync.
Two decks leave a seam down the middle. A mattress connector or a foam gap filler is the usual fix and is rarely included in the bundle price.
13 offer a true split king and 2 split in Cal king only. Ranked on value, because the split upgrade is fundamentally a price decision.
| Base | Price | Capacity | Brand trial | Warranty | Split king |
|---|---|---|---|---|---|
| Rize Contemporary IV | $799 | 700 lbs | 120 nights | 10 yrs (longest term) | Yes |
| Symphony Sleep Esquire ES500 | $899 | 750 lbs | 120 nights | 15 yrs (longest term) | Split Cal king only |
| Ergomotion Quest 4.0 | $1,099 | 750 lbs | 90 nights | 15 yrs (longest term) | Yes |
| Symphony Sleep Elegance ES600 | $1,249 | 750 lbs | 120 nights | 20 yrs (longest term) | Split Cal king only |
| Nectar Adjustable Base | $599 | 700 lbs | 50 nights | 3 yrs (longest term) | Yes |
| Ergomotion Ascend Hi-Low with Tilt | $1,799 | 750 lbs | Not published | 10 yrs (longest term) | Yes |
| Avocado Eco Adjustable Base | $1,199 | 750 lbs | 100 nights | 5 yrs (longest term) | Yes |
| Malouf Structures S755 | $1,599 | 800 lbs | 100 nights | 15 yrs (longest term) | Yes |
| Avocado Eco Plus Adjustable Base | $1,699 | 750 lbs | 100 nights | 5 yrs (longest term) | Yes |
| Symphony Sleep Estate ES700 | $1,799 | 850 lbs | 120 nights | 25 yrs (longest term) | Yes |
| Ergomotion ErgoSportive | $1,899 | 750 lbs | 120 nights | 10 yrs (longest term) | Yes |
| DreamCloud Adjustable Base | $799 | 750 lbs | 50 nights | 5 yrs (longest term) | Yes |
| Saatva Adjustable Base Plus | $1,395 | 850 lbs | 365 nights | 25 yrs (longest term) | Yes |
| Reverie R650 Power Base | $2,299 | 850 lbs | 101 nights | 20 yrs (longest term) | Yes |
| Ergomotion Dawn House Bed | $4,399 | 750 lbs | Not published | 10 yrs (longest term) | Yes |
Feature-rich adjustable base with massage and USB at a competitive price
Highest value rating among split-capable bases at 9.4/10.
Premium adjustable base with wall-hugging design and full-body massage
Longest published brand trial here at 365 nights.
Top-of-the-line adjustable base with app control and smart home integration
Highest published capacity here at 850 lbs.
Two twin XL bases side by side under the width of a king. Each side raises and lowers independently, so one person can sit up to read while the other stays flat. A standard king adjustable base moves both sleepers together.
Yes. Two twin XL mattresses sit on the two decks. A single king mattress spanning both sides cannot flex independently, which defeats the point of the split and stresses the mattress.
Split king is two twin XL decks, 38 by 80 inches each. Split Cal king is two 36 by 84 inch decks — narrower and longer. They are not interchangeable and the sheets are different, so match the size to the mattresses you plan to buy.
You need twin XL fitted sheets, two of them, plus a king flat sheet or duvet across the top. Split-king sheet sets sold as a bundle are just that combination. Standard king fitted sheets will not work with independently moving sides.
It is worth it when the two of you want different positions — one snores, one reads, one has reflux. If you both sleep flat and only use the base occasionally, a standard king costs less and needs one mattress instead of two.
Costco's published guarantee has no fixed deadline on merchandise outside its listed exceptions, and bed bases are not on that list. Our Costco return policy guide sets out what the guarantee covers and where the manufacturer's warranty takes over.
Before you buy, read the brand: construction, pricing bands, trial and warranty terms, and how each company's lineup performed in our Encinitas lab.
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