ChartStandard dimensions — nothing to enter.
A Split King mattress is 76 × 80 inches — 6 ft 4 in wide by 6 ft 8 in long, or 193 × 203 cm. It needs a room of at least 11 × 9 ft.
| Measurement | Size | Metric or area |
|---|---|---|
| Width | 76 in | 193 cm |
| Length | 80 in | 203 cm |
| In feet | 6 ft 4 in × 6 ft 8 in | — |
| Sleeping surface | 42.2 sq ft | — |
| Smallest room it fits | 11 × 9 ft | 99 sq ft |
| Comfortable room | 13 × 10 ft | 130 sq ft |
| Fitted sheet | two 38–39 × 80 in (twin XL) | typical range |
| Flat sheet | two 66–68 × 102 in, or one 108 × 102 in | typical range |
| Comforter or duvet | 102–108 × 90–94 in | typical range |
| Pillows | 2 king (20 × 36 in) | — |
| Rug under the bed | 9 × 12 ft | — |
Room sizes assume 24 in of clear floor down each side and at the foot as a minimum, 36 in to be comfortable. Bedding is not standardized the way mattresses are. Mattress dimensions are fixed, but sheet and comforter cuts vary between manufacturers, so these are the common US retail ranges — check the size on the packaging of the set you are buying.
The mattress itself. A Split King is 76 × 80 inches — 6 ft 4 in wide by 6 ft 8 in long, or 193 × 203 cm. It is also sold as a Dual King. Two twin XL mattresses that together measure exactly a king. Each side moves on its own adjustable base, which is the whole reason the size exists.
The room it needs. Bed dimensions are only half the question; the floor around the bed is the other half. The rule used across this site is 24 in of clear floor down each side and 24 in at the foot as the minimum you can live with, and 36 in as the figure that fits a nightstand and lets two people pass. For a Split King that is 11 × 9 ft at minimum and 13 × 10 ft to be comfortable. Those are the same numbers the mattress size chart uses, because both come from the one rule.
Bedding, and why these are ranges. The fitted sheet is cut to the mattress, so a Split King fitted sheet runs two 38–39 × 80 in (twin XL). Everything else is deliberately larger: the flat sheet at two 66–68 × 102 in, or one 108 × 102 in and the comforter at 102–108 × 90–94 in have to hang over the sides and the foot, which is why a comforter bought to the mattress size always looks too small on the bed. Bedding is not standardized the way mattresses are. Mattress dimensions are fixed, but sheet and comforter cuts vary between manufacturers, so these are the common US retail ranges — check the size on the packaging of the set you are buying.
How it compares. A Split King and a King measure exactly the same, 76 × 80 in. A Split King is 4 in wider and 4 in shorter than a California King (76 × 80 in against 72 × 84 in). Full dimensions for every size sit on the mattress size chart.
Pocket depth still matters. These dimensions describe the mattress footprint, not its height. A fitted sheet also has to clear the mattress depth plus any topper, which is the measurement most often got wrong — the bedding size chart covers the depth bands.
A Split King mattress is 76 × 80 inches, which is 6 ft 4 in wide by 6 ft 8 in long. In centimeters that is 193 × 203 cm.
A 11 × 9 ft room (99 sq ft) is the smallest that leaves 24 in down each side and 24 in at the foot. 13 × 10 ft (130 sq ft) is where it stops feeling tight and a nightstand fits on both sides.
It is built for two adults who want independent adjustment. Split across two sleepers, a Split King gives each person 38 in of width — a single bed is 38 in for comparison.
Fitted sheet two 38–39 × 80 in (twin XL), flat sheet two 66–68 × 102 in, or one 108 × 102 in, comforter or duvet 102–108 × 90–94 in, and 2 king (20 × 36 in). These are ranges rather than one number because bedding cuts vary by manufacturer, unlike the mattress itself. Sheets are sold by bed name, so buying "Split King" is right — the mattress depth is the measurement worth checking on the packaging.
A Split King and a King measure exactly the same, 76 × 80 in. The King needs the bigger room: 11 × 9 ft against 11 × 9 ft.
A 9 × 12 ft rug is the size that works in most rooms — it carries the bed and still shows floor on all three walking sides. The exact answer depends on your room, which is what the rug size calculator works out.