Cot Bed and Small Single Mattress Sizes
By Kaiser Khan, Editor Updated First published
Desk research from official sources. Not a product test or medical advice. How we check facts.
In short
A common UK cot bed mattress measures about 70 × 140 cm and must fit the cot snugly for infant safety. A UK Small Single is typically 75 × 190 cm — narrower than a standard Single at 90 × 190 cm — used for children, compact rooms and some bunks. Confirm exact manufacturer dimensions before ordering sheets or frames.
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How it works
| Size name | Width (cm) | Length (cm) | Width (in) | Length (in) |
|---|---|---|---|---|
| Cot bed (common UK) | 70 | 140 | 27.6 | 55.1 |
| Small Single | 75 | 190 | 29.5 | 74.8 |
| Single (reference) | 90 | 190 | 35.4 | 74.8 |
Cot fit is a safety size problem
Unlike adult approximate sizes, cot mattresses must match the cot’s internal space. A mattress that is too small creates dangerous gaps. One that is too large will not sit flat. Use the cot maker’s stated centimetres.
Progression through UK children’s sizes
- Cot bed — ~70 × 140 cm (verify per cot).
- Small Single — 75 × 190 cm.
- Single — 90 × 190 cm (standard adult/guest Single).
Adult couples’ sizes begin at Small Double / Double.
Related BedGuide entries
Frequently asked questions
What size is a UK cot bed mattress?
Many UK cot bed mattresses are approximately 70 cm by 140 cm. The critical rule is a snug fit in the specific cot with gaps small enough that a child cannot become trapped — follow the cot manufacturer's stated mattress size.
When do children move from cot to Small Single or Single?
Timing depends on height, climbing behaviour and safety guidance from carers. Dimensionally, Small Single (75×190 cm) and Single (90×190 cm) are the common next UK footprints.