What Is a Cot Bed and How Does It Differ From a Cot?

A cot bed is a convertible baby bed that starts as a cot and later transforms into a toddler bed, while a cot is a fixed, enclosed sleeping space.

For the full breakdown, see our best Adult Cot Bed guide.

The terminology can feel confusing, especially since “cot” and “cot bed” are everyday words in the UK, Australia, and New Zealand, but US families mostly shop for a crib. Wherever you are, the practical question is the same: what’s the difference between these two sleeping setups, and which one fits your child’s needs?

This guide breaks down the key distinctions in size, age range, safety standards, and overall value. You’ll also find the timing advice that matters most—knowing when to switch modes to keep your child safe.

Cot Bed vs Cot: Core Differences Explained

A standard cot is an enclosed sleeping facility with raised sides and ends for an infant or child. It has one fixed purpose. A cot bed, by contrast, is a convertible product: it starts as a cot and later converts into a small toddler bed, extending its useful life.

Industry guidance describes cot beds as products that convert from cot mode to a small bed, commonly used from birth to about four years. The longer lifespan is the central reason parents choose them.

Size and Age Range

The most cited distinction between the two is straightforward:

• Cot: typically 60 x 120 cm, used from birth until around 2 years.
• Cot bed: typically 70 x 140 cm, used from birth to 4–5 years.

The extra width and length is what allows a cot bed to serve as a proper toddler bed later. A standard cot’s smaller footprint means a child outgrows it sooner, often by their second birthday.

How Cot Bed Conversion Works and When to Do It

Converting a cot bed is normally a simple procedure: you remove one or both side rails, lower the mattress base, and the cot becomes a low, accessible toddler bed. The exact steps always come from the manufacturer’s instruction manual, and you should follow those instructions to the letter.

European safety guidance offers one critical piece of timing advice: conversion should ideally happen before a baby can climb out, to reduce the risk of falls. If your child is showing signs of climbing, don’t wait for their second birthday—make the switch sooner.

A common mistake is keeping the cot bed in cot mode too long because it still fits. The moment a child can climb out, the raised sides stop being a safety feature and become a hazard.

After conversion, most parents add a low bed rail or place the bed against a wall for extra security, though the maker’s instructions remain the final authority on that setup.

Safety Standards for Cots and Cot Beds

Safety regulations treat a cot bed exactly as they treat a cot when it’s in cot mode—there is no separate, more lenient category. In Australia and New Zealand, cots must comply with the mandatory standard based on AS/NZS 2172, and this applies to both new and second-hand products intended for home sleeping use.

New Zealand’s product safety guidance also clarifies what is not covered by the household cot standard: folding cots, carry cots, cradles, and bassinets all fall outside its scope. If you’re considering one of these alternatives, check whether a different safety rule applies to it.

There is also a modern note on design: cots should no longer have a side that fully drops down. This classic “dropped-side” design has been phased out of new products for safety reasons, so avoid second-hand models that feature one.

The US Perspective: Crib Is the Term You’ll Hear

US families rarely encounter the words “cot” or “cot bed” in stores. The standard American term for an infant sleeping enclosure is simply crib, and the convertible versions are called convertible cribs.

A convertible crib can transform into a toddler bed, a daybed, and sometimes a full-size bed, which is the same core idea as a cot bed. The size standards differ, though. US cribs are built to a specific federal standard that dictates mattress dimensions, so the 70 x 140 cm metric used in the UK and Australia is not a universal measurement.

If you’re in the US and shopping for this type of furniture, search for “convertible crib” rather than “cot bed.” For UK, Australian, or New Zealand readers, “cot bed” is the term that will find you the right product.

Mattress fit is a universal concern. A mattress that fits a standard cot will not necessarily fit a cot bed, and a mattress with too much gap around the edges is a suffocation hazard. Always match the mattress to the exact model you own, and never reuse a mattress that doesn’t fit snugly.

One more point applies to any market: converted products should follow the maker’s instructions, and mattress-related standards may differ by region. If you buy a second-hand cot or cot bed, verify it meets the current safety standard for your country before using it.