Many cots will have the mattress size on a label somewhere on the cot, sometimes it is a small label on the cot base or on a side panel, check this first.

Mattress sizes are all important to your baby's safety in the cot.
If the mattress is too small there is a real danger of your baby's head getting trapped between the mattress and the sides of the cot. If your mattress is too big either it wont fit or you will not be able to operate the dropside (if your cot has one) and you may not be able to tuck bedding in the sides without making an uncomfortable bulge in the in mattress.

Select a decent tape measure ( please no old school rulers!) we are talking accurate measurements here to within a centimetre or half inch

First Measure the internal dimensions of the cot length from end to end and measure at the base of the cot along the middle of the mattress base where the mattress will sit.Now measure the width from longside to longside along the middle of the mattress base where the mattress will sit.

Now you have these measurements you must not choose a mattress size that would leave a gap of more than 4cm between the edge of the mattress and the sides of the cot, either on the width or the length.For instance if the inside measurements of your cot is 123cm x 62cm then the smallest mattress you can safely have is 119cm x 58cm. You could have a mattress size from 119cm x58cm to 121cm x 60cm. any tighter and you wont move the dropside or tuck the blankets in.

Very important to ensure that you do not have more than a 4 cm gap between the edge of mattress and the side of the cot. ( this includes pushing the mattress tight up to one side of the cot to create a gap on the other side)

99% of all Cots or Cot beds on the UK will take one of our standard size mattress

We have listed a selection of popular cots and the mattress sizes they take