If you’re considering an adjustable bed, one of the first questions you’ll likely ask is what sizes are available. Unlike standard divan or frame beds, adjustable beds can vary slightly depending on whether they are designed for one person or two and whether they offer dual controls.

Understanding how sizes work, particularly when it comes to split mattresses and base slits, can help you choose the right setup for your bedroom and sleeping needs.

Standard Adjustable Bed Sizes

Most adjustable beds are available in similar widths to traditional beds, including:

  • 3’0″ Single

  • 4’0″ Small Double

  • 4’6″ Double

  • 5’0″ King Size

  • 6’0″ Super King Size

However, the internal construction may differ from a standard bed base, especially in larger sizes.

MiBed Executive with Conwy mattress

Single and Small Double Adjustable Beds

A 3’0″ single and 4′ small double adjustable beds are designed for one sleeper and operate with a single motor and handset control. This is often the most popular choice for individuals who want adjustable comfort for reading, watching television or improving circulation.

Single adjustable beds are commonly chosen for:

  • Smaller bedrooms

  • Guest rooms

  • Individual comfort needs

  • Mobility or health support

Brands such as Respa, Mi-Bed, and Adjust-A-Bed all offer single adjustable options with different mattress types and support systems.

MiBed Cool Gel Support Executive Adjustable Bed

Super King Adjustable Beds – What’s the Difference?

When moving up to super king size adjustable beds, there are usually two configurations available.

1. One-Piece Adjustable Base

In some models, the entire mattress adjusts as one unit. This means both sleepers move together when the bed is raised or lowered.

This option may suit couples who:

  • Prefer the same sleeping position

  • Have similar comfort needs

  • Want a simpler setup

2. Split or Dual Adjustable Base

Many super king size adjustable beds are built with two separate mechanisms within one frame.

These beds typically feature:

  • Two independent motors

  • Two separate mattresses (or a split mattress with slits)

  • Dual handset controls

This allows each sleeper to adjust their side independently without disturbing the other.

MiBed Cool Gel Lux Executive Adjustable Bed

What Are Mattress Slits in Adjustable Beds?

On some adjustable beds, you may notice a “slit” running partially down the middle of the mattress. This isn’t a fault, it’s a design feature.

The slit allows each side of the mattress to bend independently when paired with a dual adjustable base. From the outside, the bed still appears as one large mattress, but internally it functions as two sections.

This setup is especially useful for couples who:

  • Have different sleeping preferences

  • Want separate head or leg elevation

  • Need individual support adjustments

Brands like Mi-Bed and Adjust-A-Bed frequently offer dual motor systems with independent control options, while Respa provides adjustable solutions that combine comfort with supportive mattress technology. Many of our adjustable beds are also available from our in-stock range for fast delivery to Belfast and Dublin, helping you enjoy improved comfort without long waiting times.

Are Super King Size Adjustable Beds Always Split?

Not always. Some 6′ adjustable beds are supplied as two linked 3′ bases that sit side by side to create a 6′ sleeping surface. Each side can operate independently.

In practical terms, this means:

  • Two separate mattresses may be supplied

  • Two remote controls are included

  • Movement on one side doesn’t affect the other

This is often the most popular option for couples seeking flexibility.

Choosing the Right Size for Your Room

Before selecting an adjustable bed size, consider:

  • Room dimensions

  • Access (stairs and doorways)

  • Whether you want single or dual control

  • If you prefer one-piece or split mattresses

Adjustable beds are slightly heavier than standard divans due to motor systems, so access planning is important.

Compare Adjustable Bed Sizes at Dalzells Beds

At Dalzells Beds, we stock adjustable beds from trusted brands including Respa, Mi-Bed, and Adjust-A-Bed, available in a range of sizes and configurations. Visiting the showroom allows you to test single and dual-control models and see how split systems work in practice.  For eligible customers, VAT Exemption may also be available. Our team is always happy to advise.

With delivery available across Northern Ireland and Dublin, and accreditation as a National Bed Federation Premier Retail Champion, Dalzells Beds provides expert guidance to help you choose the right adjustable bed for your needs.  Find out more about why customers choose us.

National Bed Federation - Premier Retail Champion