How long can you use a cot bed?

[PoppyRose21]

My three year old nephew still sleeps in the toddler bed that his cot bed converted into, but he's small for his age. Do children as old as six still sleep happily in a converted cot bed or are they ready for a full single bed earlier than that?
Also, while set up as a cot is a cot bed just the same as a cot but bigger? Do they still have different heights and drop down sides?
I really do need to take myself off to Toys R Us or Mothercare and look at some examples...

I don't understand why you are thinking about this. Surely it isn't your concern?

FWIW though. My oldest was in a cotbed (same size as large cot) at 2 and a single bed at 3. Youngest is 3 and wants the cotbed as a cot still.

Yep, my son still fitted into his cot bed at six, when he got a single bed and my 3 year old then moved out of her cot into the cot bed. When they are too big for it will depend on the size of the child! Yes my cot bed had drop side and mattress can go at three different levels.

dd1 was in a cotbed (as a cot still, with sides on) until past 3. she was a big (actually, hugely tall) toddler, and fitted fine. she then went into a normal single bed.

dd2 was in a cotbed as a cot until 2ish, and then as a bed until she was about 5 (she is quite small, but would have had room still if she didn't have quite so many stuffed animals on her bed )

ds is still in a cotbed as a cot - he's 20 months. no idea what we'll do with him, yet (although he has managed to climb out once, he thankfully hasn't repeated it, so we're hanging inthere with the cot sides for now)