King vs California King: which is bigger?
A King mattress is 76 × 80 in and a California King is 72 × 84 in. The King is 4 inches wider; the California King is 4 inches longer. The King has slightly more surface area, 6,080 versus 6,048 square inches (0.5% more), so a California King is longer and narrower, not bigger.
Our diagram
King and California King, drawn to scale
| Measure | King | California King | Change |
|---|---|---|---|
| Width | 76 in193.0 cm | 72 in182.9 cm | −4 in−10.1 cm |
| Length | 80 in203.2 cm | 84 in213.4 cm | +4 in+10.2 cm |
| Area | 6,080 sq in42.2 sq ft | 6,048 sq in42.0 sq ft | −32 sq in−0.5% |
| Area (m²) | 3.92 m² | 3.90 m² | −0.02 m² |
| Per person, two sharing | 38 in | 36 in | −2 in |
Figures: Target mattress size chart, checked 2026-09-24. Areas, differences and per-person widths are our arithmetic on those figures.
Target and Sleep Foundation publish the same figures for both sizes.
Common questions
Is a California King bigger than a King?
No. It is 4 inches (10.2 cm) longer but 4 inches (10.1 cm) narrower, and 32 square inches smaller overall. The centimetre differences round differently because both are converted from inches.
Which one fits my room?
Measure the wall the headboard goes against and the distance to the opposite wall or door. A King needs 4 more inches of wall; a California King needs 4 more inches of floor length. Then allow for the frame, which is larger than the mattress (see bed frame dimensions).
Do King sheets fit a California King?
Not by design. A fitted sheet made for a 76 × 80 in King is cut 4 inches wider and 4 inches shorter than a 72 × 84 in California King mattress. Check the sheet maker's stated mattress size; none of the sheet makers in our dataset lists one fitted sheet for both sizes.
Are two Twin XL mattresses the same as a King?
It depends on which published Twin XL width you use. Two 38-inch Twin XLs (Sleep Foundation's figure) make 76 × 80 in, a King. Two 39-inch Twin XLs (Target's figure) make 78 × 80 in, 2 inches wider than a King. Measure both mattresses before buying a split-king frame or bedding.
A US King is not a UK King or a French king size
The name "King" means a different bed in each market. A US King is 193 cm wide; a UK King is 150 × 200 cm and a French "king size" is 180 × 200 cm. By measurement, a US King sits between the UK Super King (180 × 200 cm) and the Emperor (200 × 200 cm). See UK vs US bed sizes.
Oversized mattresses such as the Alaskan King or Texas King are not in our chart: we have not found a manufacturer or industry source that sets standard dimensions for them.
Sources
- Target mattress size chart
- Sleep Foundation twin size guide
- Which? UK mattress size guide
- IKEA France size guide
Sources are grouped by the market they are written for. Each figure was checked against its source on the date shown.