The number that matters on a bunk bed is 3.5 inches: the largest opening the standard allows in most guardrails and end structures.

The US Consumer Product Safety Commission received 50 records of deaths of children 17 and under from strangulation or suffocation caused by bunk bed entrapments between 2009 and 2018 (most were entrapment; a few were hangings). Of those, 63% were aged 3 or younger. A bunk bed, by definition, is any sleep structure with at least one mattress foundation more than 30 inches above the floor. The standard sits at 16 CFR part 1213.

A shopper's checklist (from CPSC's guide for sellers)

  • Guardrails on both sides of the upper bunk, one running continuously head to foot, the other either continuous or with no gap over 15 inches at either end.
  • No openings over 3.5 inches in the guardrails or between the rail and mattress foundation, or in the upper bunk's end structures. Lower bunk end structures: no openings over 3.5 inches unless they are 9 inches or more.
  • Guardrail tops at least 5 inches above the mattress top.
  • Ladder openings either over 9 inches or under 3.5 inches.
  • No vertical protrusions (ladder stiles, corner posts) rising more than 3/16 inch above rails.
  • A permanent label on entrapment and fall hazards, the correct mattress size and a warning against children under 6 on the upper bunk.
  • All parts and hardware present, and no cracks in paint or metal near the welds on tubular metal beds.

Use the mattress size on the label. Recalled bunk beds cannot legally be sold, so check cpsc.gov/recalls. Follow the maker's manual for assembly.

This is a US standard. We have not covered UK or EU rules.

Last checked: 21 October 2026. General information, not legal, medical or financial advice. Sources: CPSC Publication 254, Resellers Guide to Selling Safer Products (February 2025; accessed 16 October 2026).