Mattress Size Glossary: California King, Eastern King, Olympic Queen, and Every Other Size Explained

Standard US size. The names California King, Cal King, and Western King all refer to the same mattress. The 'Western King' name originated in the 1960s when West Coast furniture makers started building longer frames for their taller clientele.

ASTM F1566 standard size

The most common US King size. 'Eastern King' is the industry term used to distinguish it from California King. In everyday retail, it is usually just called 'King' unless ambiguity exists.

ASTM F1566 standard size

Continental European standard. Varies slightly by country (some use 180x200). Smaller than both US Kings. Do not buy EU King bedding expecting it to fit a US Cal King.

Non-standardised; varies by country

The original 'double' bed that was meant for two people before Queen and King became standard. Now considered a solo sleeper size by most adults. Still common in apartments and guest rooms.

ASTM F1566 standard size

Non-standard oversized size offered by some specialty brands. Not available from mainstream mattress brands. Requires custom bedding.

Non-standard; manufacturer-specific

Non-standard size. 6 inches wider than a standard Queen. Rare. Not offered by mainstream brands. Bedding is extremely limited.

Non-standard; manufacturer-specific

The most common US mattress size overall. The starting point for most couples. Cal King adds 12 inches of width and 4 inches of length. Standard King adds 16 inches of width.

ASTM F1566 standard size

RV-common size. Five inches shorter than standard Queen. Designed for recreational vehicles with storage below. Bedding is available from camping/RV suppliers.

Common RV size

Two XL Twin mattresses placed side by side on an adjustable base. Each partner can independently adjust head and foot elevation. Requires two XL Twin fitted sheets, not a single Cal King sheet.

Adjustable base configuration

Two standard TwinXL mattresses placed side by side on an adjustable base. The most common split configuration. TwinXL sheets are widely available. Requires two TwinXL fitted sheets, not a single King sheet.

Adjustable base configuration

UK standard large bed. Narrower than both US Kings and shorter than the US Cal King. UK Super King sheets will not fit a US Cal King. This is a common mistake for American expats in the UK or UK buyers in the US.

UK standard

Waterbed-era size from the 1970s-80s. Essentially a very wide single sleeper bed. Rarely sold today except in specialty waterbed communities.

Legacy size; non-standard

Non-standard oversized size. Requires custom bedding, custom frames, and a very large bedroom. Not available from mainstream brands.

Non-standard; manufacturer-specific

The standard single sleeper size. Fits most children and solo teen sleepers. Common in bunk beds and daybeds. Often the baseline comparison for per-person width: 38 inches = one twin = one adult's minimum comfortable solo width.

ASTM F1566 standard size

Standard college dorm size. Five inches longer than standard Twin. Same width as Twin. Two TwinXLs side by side form a Split King (76x80 inches total). By far the most common single-sleeper size for tall people.

ASTM F1566 standard size

UK standard King. Closer to a US Queen in width. NOT equivalent to a US King despite sharing the name. American buyers moving to the UK are often surprised to find UK King bedding fits what they would consider a Queen.

UK standard