A cot bed mattress is typically 70 x 140 cm (about 27.5 x 55 in), though sizes vary by country and brand.
If you’re shopping for a cot bed mattress, the 70 x 140 cm size is the standard you’ll see most often. That’s roughly 27.5 inches by 55 inches. But here’s the catch: “cot bed” means different things in different markets, and brands occasionally sell nonstandard sizes.
Cot Bed Mattress Sizes by Region
The answer depends heavily on where you live. In the UK and Europe, cot beds almost always take a 70 x 140 cm mattress. In the US, the term “cot bed” isn’t standard retail language—you’re likely looking at a crib mattress instead.
- UK/Europe cot bed: 70 x 140 cm (27.5 x 55 in)—the most common size for cot beds.
- UK/Europe standard cot: 60 x 120 cm (23.6 x 47.2 in)—the smaller standard cot mattress size.
- US crib mattress: 27 1/4 x 51 5/8 in (about 69 x 131 cm)—full-size crib mattresses must meet this minimum.
- Australia/NZ cot: typically 59 x 119 cm or 60 x 120 cm, though the current NZ standard can be 69 x 130 cm.
These differences matter. Ordering a UK 70 x 140 cm mattress for a US crib—or vice versa—leaves dangerous gaps. T3’s kids mattress size guide lists several cot-bed-related dimensions, including 68 x 122 cm, 69 x 139 cm, and 70 x 160 cm, which shows just how much variation exists between brands.
Why Measuring the Cot Beats Reading the Label
Manufacturers label mattresses by name, not by universal standards. One UK guide notes that cot-bed mattresses should only be used in cots with internal dimensions of 700–710 mm wide and 1400–1410 mm long—but that’s just one cot model. Australian guidance lists a standard of 1300 x 690 mm, which is close to but not identical to the UK figure.
Before buying anything, measure the cot’s internal width and length at the widest points. Compare those numbers against the mattress specifications, not the marketing name. A mattress that’s too small lets a baby’s limbs slip into the gap; one that’s too large won’t lie flat.
If you’re ready to buy and want to compare tested options side by side, our roundup of the best cot bed mattresses covers models that fit the standard 70 x 140 cm frame.
Safety Guidelines for Cot and Crib Mattresses
Fit isn’t just about comfort—it’s a safety issue.
Thickness matters too.
| Region | Standard Mattress Size | Notes |
|---|---|---|
| UK/Europe cot bed | 70 x 140 cm | Most common cot bed size |
| UK/Europe standard cot | 60 x 120 cm | Smaller cot size, also seen in NZ |
| US full-size crib | 27 1/4 x 51 5/8 in | Minimum dimensions; max 6 in thick |
| Australia/NZ cot | 59 x 119 cm or 60 x 120 cm | NZ standard can reach 69 x 130 cm |
Common Mistakes When Buying a Cot Bed Mattress
The most frequent error is trusting the label instead of the tape measure. “Cot bed” means different dimensions in different countries, and some brands sell nonstandard sizes like 68 x 117 cm or 69 x 139 cm. Another trap: confusing a cot bed with small single bedding in the US, which is often 30 x 75 in—that’s an adult-style product, not a baby mattress at all.
If you’re outside the UK or Europe, assume the 70 x 140 cm standard doesn’t apply to you. US shoppers should search for crib mattress sizes instead, and buyers in Australia or New Zealand should confirm their local standard before ordering.
References & Sources
- Pottery Barn Kids. “What Is the Standard Crib Mattress Size and How to Choose Yours.” Details US crib mattress dimensions and safety limits.
- T3. “Kids Mattress Size Guide.” Lists UK cot bed sizes including 70 x 140 cm and brand variations.
- U.S. News. “Mattress Sizes.” Explains US crib mattress terminology and dimensions.
FAQs
Is a cot bed mattress the same as a crib mattress?
No. Cot beds are a UK/European product taking a 70 x 140 cm mattress, while US cribs use a minimum 27 1/4 x 51 5/8 in mattress. The terminology and measurements are different, so a mattress made for one market typically won’t fit safely in the other.
Can I use a standard cot mattress in a cot bed?
Usually not safely. A standard cot mattress is 60 x 120 cm, which is considerably shorter than the 140 cm length of a cot bed mattress. Using the smaller one leaves a significant gap at the foot of the bed, creating a trapping hazard.
How do I know which mattress size my cot bed needs?
Measure the internal width and length of the cot bed itself. Most UK cot beds take a 70 x 140 cm mattress, but some brands use 68 x 122 cm, 69 x 139 cm, or 70 x 160 cm. Always compare your measurements against the mattress specs before ordering.