A cot bed is a nursery bed that starts as an enclosed crib and converts into a toddler bed by removing one or more side rails, staying useful from birth to about age 4 or 5.
One label, three different beds — and in the US the same furniture often hides behind a name most shoppers have never heard. A cot bed is the convertible version: an enclosed infant bed whose sides come off later to become a toddler bed. American stores usually call it a convertible crib, which is the term worth searching when you shop.
Cot Bed vs Crib vs Toddler Bed: What Sets Them Apart
A crib is the smallest and simplest of the three, built for one stage only; a cot bed is larger and converts; a toddler bed is the low transitional frame a child graduates into. The core difference is whether the bed grows with your child.
- Crib — an enclosed infant bed, used from birth until your baby outgrows it, often within the first year.
- Cot bed (US: convertible crib) — a larger enclosed bed with removable side rails or panels. Those rails come off to create the toddler setup, and the bed is commonly described as usable from birth to roughly age 4 or 5.
- Toddler bed — a low, open frame used after the crib stage, usually joined when a child is too big for the crib or starts climbing out, with the move often suggested around 2.5 to 3 years.
Size runs smallest to largest in the same order: crib, then cot, then cot bed. A toddler bed is not automatically the same size as a crib, because sources define cot beds both by conversion and by dimensions, and the sizes change from market to market.
What Size Is a Cot Bed, and Why the Mattress Matters
A cot bed is bigger than a standard crib, but the mattress you put in it has to match the frame exactly.
That wording matters: the wrong mattress size can leave dangerous gaps around the edges, which is exactly the kind of gap you avoid by buying a full-size crib mattress for both stages.
Across the Atlantic, cot-bed mattresses are typically cited at 120 × 60 cm or 140 × 70 cm, which is another reason the three terms do not line up neatly across countries. Check the frame’s stated mattress size before you buy anything to go inside it.
How the Conversion Actually Works
The conversion is mechanical, not a rebuild: you remove one or more side rails or panels from the enclosed cot, and the remaining base becomes an open toddler bed at floor height. That single feature is what separates a cot bed from a plain crib and what earns it the longer lifespan.
Because the bed serves two stages, the practical math favors it over buying a crib and a toddler bed separately. If you’re comparing frames stage by stage, this walkthrough of the best baby cot beds for your nursery covers the models that make the switch cleanly. The timing of the switch is your baby’s call, not a calendar’s — climbing out of the crib is the usual signal.
If you’d rather nail down the terminology before choosing, the reviews at MadeForMums on choosing a cot or cot bed and at Mother & Baby on cots and cot beds both walk through how these frames are described in practice. The one mistake worth dodging: treating “cot,” “crib,” and “cot bed” as universal synonyms. The terms shift by region, so define what you want — enclosed, or convertible — and shop by that.
FAQs
Is a cot bed the same thing as a crib?
Not quite. A crib is a fixed infant bed, while a cot bed is the convertible version that turns into a toddler bed once the side rails come off. In the US, stores usually sell cot beds under the name “convertible crib,” so search that term if “cot bed” returns few results.
What age do you move a child to a toddler bed?
Most guidance points to around 2.5 to 3 years, but the better trigger is behavior. Move your child when they start climbing out of the crib, or when they simply no longer fit comfortably inside it — those signals matter more than any age on a chart.
Can a toddler bed use a regular mattress?
A mattress that doesn’t fit snugly can leave gaps around the edges, so match it to the frame.
References & Sources
- MadeForMums. “Cot or Cotbed: Which Should You Choose?” Explains how cots and cot beds are described and chosen.
- Mother & Baby. “Best Cots, Cot Beds and Cribs.” Covers cot, crib, and cot bed differences and typical sizes.
