Bed Trundle – UK Sizes Mattress Tips and Top Retailers

A trundle bed is a practical space-saving solution: a main bed with a second mattress stored underneath on a wheeled frame. Designed for guest rooms, children’s sleepovers, and compact apartments, this pull-out bed concept has evolved over centuries. In the UK, the standard dimensions differ from North American sizes, making it essential for buyers to understand sizing, mattress thickness, and frame compatibility before purchasing.

The basic mechanism is simple: the lower bed slides out from under the main frame when needed and tucks away during the day. Modern trundle beds often include storage drawers or pop-up designs that elevate the secondary mattress to the same height as the main bed for adult comfort. While the idea is straightforward, choosing the right model involves careful attention to dimensions, materials, and intended use.

For UK shoppers, the market offers options from specialist retailers, but many guides reference US Twin sizes (38” x 75”) rather than the UK standard Single (36” x 75”). Verifying compatibility is a critical first step. This guide covers everything from size variations to mattress thickness and retailer recommendations for 2025.

What Is a Trundle Bed and How Does It Work?

• Trundle beds are a 2-in-1 solution, turning any room into a guest space instantly.
• Most trundle beds are low-profile; check mattress thickness (typically 6–8 inches recommended).
• Single trundle is the most common; double and queen trundles exist but may require more floor space.
• IKEA does not currently offer a dedicated trundle bed in the UK; alternatives are available from specialist retailers.
• Adults can sleep comfortably if the mattress is of adequate quality; trundle beds are not just for children.

What Sizes Do Trundle Beds Come In?

Single Trundle Bed (UK Standard)

In the UK, the most common trundle bed size accommodates a Single mattress (36” x 75”). This is narrower than the US Twin (38” x 75”). Buyers must verify that the frame is designed for UK dimensions, as many imported guides assume Twin sizing. A single trundle is ideal for children’s rooms or compact guest spaces.

Double and Queen Trundle Beds

Double trundle beds (typically a double top bed with a single trundle) and queen trundle beds exist but are less common. The lower mattress is often shorter to allow clearance. For example, a queen trundle might use a 38” x 72” mattress on the bottom. These configurations require more floor space and are best suited for larger guest rooms.

Under-Bed Trundle (No Top Bed)

An under-bed trundle is a standalone wheeled frame that slides under an existing bed. It does not include an upper bed and is used purely to add a second sleeping surface. This option is popular for maximising space in children’s rooms or for occasional guest use. As with other types, fit depends on the frame’s internal height and the mattress thickness.

Are Trundle Beds Comfortable and Suitable for Adults?

Comfort Depends on Mattress Quality

A trundle bed can be comfortable for adults if the mattress provides adequate support. Thinner mattresses (4–6 inches) are easier to store but may lack cushioning for larger individuals. An 8-inch foam or memory foam mattress is preferred for adult comfort, provided the frame has enough clearance to slide without jamming. Source: Miller Waldrop.

Weight Limits and Frame Strength

Most trundle beds have a 250-pound weight limit, while standard daybeds support up to 400 pounds. Verify the frame’s capacity if you plan to host adult guests. Metal frames tend to be more durable for frequent use, while wooden frames are often more expensive but aesthetically pleasing. Source: Cool Kids Bed.

Pop-Up Trundle for Full Height

Pop-up trundles raise the lower mattress to the same height as the top bed, creating a seamless sleeping surface. This design is especially suitable for adults, as it eliminates the low-profile feel of standard trundles. For UK buyers, a pop-up trundle is a good choice when full-height sleeping space is needed. Source: Mattress Insider (see earlier note).

Do You Need a Special Mattress for a Trundle Bed?

Thickness Is the Key Factor

Most trundle models require a mattress no thicker than 6 inches (15 cm) to roll smoothly under the main frame. Some frames with extra internal height can accommodate 7 or 8 inches, but you must measure the height from the support deck to the underside of the bed before purchasing. Source: Cool Kids Bed (see earlier note).

Best Materials for Trundles

Foam and memory foam mattresses are the top choices because they are lightweight, flexible, and easy to slide. Hybrid mattresses are acceptable if they remain under the thickness limit. Coil or pillow-top designs are often too tall or rigid for enclosed trundles and may prevent smooth sliding. Source: Bunk Beds Canada (see earlier note).

Buying with Mattress Included vs. Separate

Some trundle beds come as a set with a mattress, ensuring fit. However, many buyers prefer to choose their own mattress for better comfort. If buying separately, always confirm the manufacturer’s recommended thickness and measure the frame’s internal height. A 6-inch foam mattress is the safest balance between smooth operation and adequate comfort.

How Have Trundle Beds Evolved Over Time?

1. 18th century: Truckle beds – low wooden frames on castors used by servants in medieval England. They slid under the master’s bed during the day.
2. Early 20th century: Pop-up trundles introduced, allowing the lower bed to be raised to the same height as the main bed for added comfort.
3. 2020s onward: Storage trundles with built-in drawers and integrated foam mattresses become popular for modern small-space living.

What Is Certain and Uncertain About Trundle Beds?

Why Are Trundle Beds Gaining Popularity in the UK?

Rising housing costs and smaller living spaces have driven demand for flexible furniture. Trundle beds offer a practical way to accommodate overnight guests without dedicating a whole room. Compared to daybeds with trundle, standalone trundle beds often include storage drawers, making them even more functional for tight spaces. While double and queen trundles are less common, they are available from specialist manufacturers. The under-bed trundle (without a top bed) is especially popular for maximising floor space in children’s rooms, where a single pull-out bed can turn a playroom into a sleepover area in seconds.

For those exploring other space-saving options, the Loft Bed – Complete Buying Guide for Adults in the UK offers another angle on vertical sleeping arrangements. And if you’re setting up a home office in a compact room, the Office Desk – Best Home Office Desks and Buying Guide covers desks that pair well with fold-away furniture.

What Do UK Retailers Say About Trundle Beds?

“A trundle bed essentially turns a normal bed into a 2-in-1 bed.” If you’re curious about mattress dimensions, you can find a helpful $5ft 5in in cm for conversions.

– HappyBeds (via product category description)

“A trundle bed is a regular bed with another bed neatly hidden underneath.”

– Time4Sleep (via product category description)

“Trundle beds with a hidden pull-out bed – perfect for guests, sleepovers and small or shared rooms.”

– Millie&Jones (via product category description)

What Is the Takeaway for UK Buyers?

For anyone considering a trundle bed in 2025, the core advice is to measure first. Verify that the frame accepts a UK Single (36” x 75”) mattress, check the internal height for mattress thickness, and choose a 6-inch foam mattress as the safest starting point. Whether for a child’s sleepover or an adult guest room, a well-chosen trundle bed offers genuine space-saving value without sacrificing comfort.

Frequently Asked Questions