King Bed Dimensions: Inches, Feet & Square Feet

A standard U.S. King mattress measures 76 inches wide by 80 inches long—about 6 feet 4 inches × 6 feet 8 inches, or 193 × 203 cm. Its rectangular mattress footprint is 42.2 square feet (76 × 80 ÷ 144). These are mattress dimensions; a bed frame, headboard or footboard may take more space. See Casper's U.S. mattress size guide for the standard-size comparison.

The 76 × 80-inch King footprint converts to 6 ft 4 in × 6 ft 8 in, or approximately 1.93 × 2.03 meters. It is 16 inches wider than a 60 × 80-inch Queen mattress in the same standard chart, while both have an 80-inch nominal length. Measure the exact mattress and frame when planning a close fit because product and frame dimensions can vary.

A Split King combines two Twin XL mattresses side by side; each is nominally 38 × 80 inches, making a combined 76 × 80-inch surface. A California King is different: it is typically 72 × 84 inches, narrower and longer than a standard King. Check the exact size name before buying sheets, a foundation or a frame. For room planning, see our average bedroom size and layout guide.