King vs California king

One is wider, one is longer. Neither is simply "bigger".

Two parents, two young children and a golden retriever laugh together on a king bed in a bright bedroom with a beamed ceiling and big windows

Short answer: a king (76 × 80 in) is 4 in wider; a California king (72 × 84 in) is 4 in longer.^{[1 · Oct 29, 2026]} Their surface areas are almost the same.^{[1 · Oct 29, 2026]} Pick a king for width (kids or a restless partner) and a California king for length (tall sleepers, pets at the foot).^{[1 3 · Oct 29, 2026]}

	King	California king
Size	76 × 80 in^{[1 · Oct 29, 2026]}	72 × 84 in^{[1 · Oct 29, 2026]}
Centimeters	193 × 203 cm	183 × 213 cm
Surface area	6,080 sq in^{[1 · Oct 29, 2026]}	6,048 sq in^{[1 · Oct 29, 2026]}
Width per person, two sleepers	38 in	36 in
One maker's minimum room	12′ × 12′^{[2 · Oct 29, 2026]}	12′ × 12′^{[2 · Oct 29, 2026]}

Actual sizes run a little small

One maker lists its kings at about 76 × 79½ in and its California kings at about 72 × 83½ in, give or take ½ in.^{[3 · Oct 29, 2026]} That's normal. Measure your frame before you buy.

Choose a king if

Two adults want the most width: 38 in each.^{[1 · Oct 29, 2026]}
A child often joins you in bed.^{[1 · Oct 29, 2026]}
You want sheets and frames that are easy to find.^{[1 3 · Oct 29, 2026]}

Choose a California king if

One of you is over about 6′2″.^{[2 3 · Oct 29, 2026]}
A pet sleeps at the foot of the bed.^{[1 · Oct 29, 2026]}
Your room is long and narrow.^{[3 · Oct 29, 2026]}

The catch: California king sheets, blankets and frames are harder to find and tend to cost more.^{[1 · Oct 29, 2026]}

Split king

A split king is two 38 × 80 in halves that make a standard king footprint.^{[4 · Oct 29, 2026]} Split sizes exist mainly for adjustable bases, where each side moves on its own, and for partners who want a different firmness on each side, as one maker explains for the split queen.^{[2 · Oct 29, 2026]}

Delivery

Kings are awkward to carry up narrow stairs,^{[2 · Oct 29, 2026]} so check that the bedroom door frame is wide and tall enough.^{[5 · Oct 29, 2026]} See our delivery guide.

Sources: 1. Sleep Foundation, Mattress sizes and dimensions guide. 2. Casper, Queen size bed dimensions: size, room fit, and how it compares. 3. Serta, King size mattress dimensions. 4. Saatva help, What are the dimensions of the Saatva foundation?. 5. Sleep Foundation, King size bed dimensions. Checked Oct 29, 2026. Trademarks belong to their owners; figures are restated in our own words and tables, not reproduced.