When it comes to trundle mattresses, the size is typically designed to be smaller than regular mattresses in order to fit beneath a standard bed frame. The most common size for a trundle mattress is a twin size, which measures approximately 38 inches wide by 75 inches long (96.5 cm by 190.5 cm). However, there are variations in size and some trundle beds may accommodate a twin XL mattress, which is the same width as a twin but has an extra 5 inches of length (80 inches total length). It is always important to measure your trundle bed space to ensure that you select a mattress that fits properly.
Understanding Trundle Mattresses and Beds
A trundle bed offers an extra sleeping space that can be tucked away when not in use. It’s a fantastic space-saving solution, often used in children’s bedrooms, guest rooms, or small living spaces. The lower bed of a trundle bed — essentially a mattress on a rolling platform — can be slid or rolled out from beneath the main bed when needed.
Common Trundle Mattress Sizes
As mentioned, the predominant size for a trundle mattress is that of a twin size, closely followed by the twin XL for those who require additional length. Here is a brief overview of each:
Twin Size Trundle Mattress: The twin mattress is the ideal size for most trundle beds. It offers ample sleeping space for a child or an average-sized adult while ensuring that it can be slid under a regular bed frame without any issues.
Our Top 5 Mattress Picks
Updated September 2026EGOHOME 8-Inch Green Tea Memory Foam Mattress, Full, Medium Firm
Best for most bedrooms. A medium-firm green tea memory foam mattress with a cooling gel layer, delivered rolled in a box.
- Full size, 8 in
- Medium firm
- Cooling green tea gel
- CertiPUR-US, fiberglass free
OhGeni Queen Air Mattress with Built-in Pump, 18-Inch Raised
Best for guests and camping. Inflates in about three minutes with the built-in pump and sits 18 inches off the floor, so it feels like a real bed.
- Queen, 18 in raised
- Built-in pump
- 800 lb capacity
- Waterproof PVC
Novilla 6-Inch Gel Memory Foam Mattress, Twin
Best budget twin. A slim gel memory foam twin that suits kids' rooms, bunk beds and trundles where a thick mattress won't fit.
- Twin, 6 in
- Gel memory foam
- Cooling
- CertiPUR-US
Zinus 8-Inch Green Tea Memory Foam Mattress, Twin
Best-known brand. Zinus's long-running green tea foam design in twin size, with both CertiPUR-US and OEKO-TEX certified materials.
- Twin, 8 in
- Green tea memory foam
- CertiPUR-US & OEKO-TEX
GAESTE 8-Inch Cooling Gel Memory Foam Mattress, Full, Medium Feel
Best for hot sleepers. Cooling gel memory foam with a medium feel, plus a machine-washable, anti-slip cover you can actually clean.
- Full size, 8 in
- Medium feel
- Cooling gel foam
- Washable cover
- Fiberglass free
Twin XL Size Trundle Mattress: A twin XL provides an extra 5 inches in length, making it suitable for taller individuals. This size of mattress can still fit under many daybeds or bunk beds with trundles but always be sure to check the measurements before purchasing.
Dimensions and Measurements
Because trundle beds are designed to be concealed under another bed, it is crucial that the dimensions of the trundle mattress are slightly smaller than the space it is meant to occupy. This allows for ease of movement when pulling it out or storing it away. To avoid any issues, here are some guidelines for measurements:
1. Height: Trundle mattresses are often thinner than standard mattresses. While a regular mattress might be 8 to 12 inches thick, a trundle mattress is usually 6 to 8 inches thick to fit within the confines of the lower bed part of a trundle bed.
2. Width and Length: Although twin and twin XL are the common sizes, always verify the size of your trundle bed. There may be instances where custom or non-standard sizes are required, especially in bespoke or artisanal bedroom furniture.
Selecting the Right Trundle Mattress
When shopping for a trundle mattress, several factors come into play. Aspects such as mattress thickness, material, and firmness can impact comfort and usability.
Choosing the Appropriate Thickness
The thickness of the mattress is particularly important because it has to fit under the main bed. Generally, a trundle mattress should not exceed 8 inches in height to ensure it can be easily stowed away. A mattress that is too thick could become jammed, damage the trundle mechanism or bed frame, or be difficult to pull out.
Material Matters: Memory Foam, Innerspring, or Hybrid?
– Memory Foam: A popular choice for its pressure-relieving qualities and ability to contour to the body. It’s also relatively lightweight, which makes moving the trundle in and out a smoother process.
– Innerspring: These mattresses have a traditional feel and are quite supportive. They can be a bit heavier, so be mindful when maneuvering a trundle outfitted with an innerspring mattress.
– Hybrid: Hybrid mattresses feature a combination of foam and spring technology, offering both support and comfort. They can be on the heavier side, similar to innerspring mattresses.
Firmness and Comfort Considerations
While the mattress should be slim enough to fit under the main bed, that doesn’t mean it needs to be any less comfortable. The firmness level you choose should be based on personal preference and the needs of whoever will be using the bed. Side sleepers might prefer a softer surface, while back or stomach sleepers might benefit from a firmer mattress.
Care and Maintenance of Trundle Mattresses
Caring for a trundle mattress can be slightly different from caring for a regular mattress due to its unique usage patterns.
Protecting Your Mattress From Wear and Damage
It’s advisable to use a mattress protector on your trundle mattress to safeguard it from spills, stains, and dust. When not in use, ensure that the mattress is covered or at least fitted with a sheet to prevent dust accumulation and possible damage from the bed frame.
Ensuring Durability and Longevity
Rotate the mattress regularly to distribute wear evenly. Since trundle mattresses are not used every day, it’s easy to overlook this maintenance step, but occasional rotation can prolong the life of the mattress.
Finishing Thoughts
The trundle mattress is an ingeniously designed space-saver and a convenient solution for occasional sleeping arrangements. The standard size for a trundle mattress is typically a twin or twin XL, with a recommended maximum thickness of around 6 to 8 inches. When selecting a mattress for your trundle bed, consider material, thickness, and firmness to ensure both fitting and comfort. With the right care and maintenance, your trundle mattress can provide comfortable sleeping arrangements for years to come. Always remember, before making any purchase, measure the allotted space to ensure a perfect fit for your new trundle mattress.
