---
title: "Kids Bed Size Journey (Cot to Single)"
description: "Educational UK map from cot to single and bunk sizes — centimetres, stages and safety checks for children’s beds."
url: "https://bedguide.co.uk/sizing/kids-bed-size-journey/"
category: "sizing"
primary_entity: "kids bed size journey"
date_published: 2026-08-03
date_modified: 2026-08-03
---

# Kids Bed Size Journey (Cot to Single)

> Children’s beds follow a size journey: cot or cot-bed, then toddler or small single, then a UK Single, and sometimes bunk or high-sleeper setups. Measure mattresses in centimetres. Safety rails, ladder clearance and weight limits matter as much as the size name. This maps usual stages — not childcare or medical advice. Follow current product safety instructions for any bed.

## Dimensions

| Size name | Width (cm) | Length (cm) | Width (in) | Length (in) |
| --- | --- | --- | --- | --- |
| Typical cot mattress (example band) (Confirm the exact cot brand size — not universal) | 60 | 120 | — | — |
| UK Small Single (common kids step) (Also called a three-quarter in some older speech) | 75 | 190 | — | — |
| UK Single (Standard next step for many older children) | 90 | 190 | — | — |

## The usual size ladder

1. **Cot / cot-bed mattress** — size is model-specific ([cot and small single](/sizing/cot-and-small-single-sizes))
2. **Toddler or small single styles** — often narrower than a full Single
3. **UK Single 90 × 190 cm** — common longer-term kids size ([UK sizes](/sizing/uk-standard-bed-sizes))
4. **Bunk / high sleeper** — still usually Single-width mattresses with extra structure rules

Details for materials and firmness myths: [kids mattress guide](/sizing/kids-mattress-guide).

## Safety checks that travel with every stage

| Check | Why |
| --- | --- |
| Exact cm fit | Gaps at the edges are unsafe in cots and some bedrails |
| Guardrails / barriers | Product-specific height and gap rules |
| Ladder and head clearance | Especially for bunks and high sleepers |
| Weight limits | Frames and top bunks are rated |
| Firm, flat sleep surface for infants | Follow current safer-sleep guidance from health authorities — not mattress marketing |

## Bunk and high sleeper branch

When space is tight, families consider [bunk beds and high sleepers](/beds/bunk-beds-and-high-sleepers). Assembly quality matters — see [assemble a bunk bed](/beds/assemble-a-bunk-bed).

## Common mistakes

- Buying “cot bed” bedding for a different centimetre size
- Putting a soft adult pillow/topper in an infant sleep space against safer-sleep rules
- Ignoring top-bunk age guidance to save floor space

## Related BedGuide entries

- [Learning path: Kids sleep sizes](/learn/kids-sleep-sizes)
- [Compare bunk vs high sleeper](/compare/bunk-vs-high-sleeper)

## Frequently asked questions

### When should a child move from a cot to a bed?

That is a parenting and safety judgement, not a BedGuide rule. Furniture literacy means matching the next mattress size in centimetres and using the right guardrails for that product. Follow the bed maker’s age and weight guidance.

### Is a UK Single the same as a kids mattress?

A UK Single (90 × 190 cm) is a standard adult single size that many older children use. Younger stages often use cot or smaller widths. Always measure.

### Are bunk beds safe for any age?

No. Bunk and high sleepers have age, weight and guardrail rules on the product. Top bunks are not for very young children. See bunk beds and high sleepers.

---

Source: https://bedguide.co.uk/sizing/kids-bed-size-journey/ · BedGuide — educational encyclopedia, no affiliate commission. Facts checked against official sources where possible; see https://bedguide.co.uk/editorial-policy. Report an error: https://bedguide.co.uk/corrections.