King Size Bed Dimensions: 76″ × 80″
Short answer: Standard king size bed dimensions are 76 inches wide × 80 inches long (193 × 203 cm, 6.3 × 6.7 ft). A King needs a room of at least 12 × 10 ft, and each of two sleepers gets 38 inches of width — the same personal space as a Twin XL bed of their own.
A king size bed measures 76″ × 80″ — that’s the widest standard mattress you can buy, with room to spare for two adults and even a small child or a large dog in the middle. This page covers everything about the King in one place: dimensions in inches, centimeters and feet, frame sizes, the room you’ll need, the difference between a King and a California King, and who should upgrade from a Queen.
King Bed Dimensions at a Glance
| Measurement | Inches | Centimeters | Feet |
|---|---|---|---|
| Mattress (W × L) | 76″ × 80″ | 193 × 203 cm | 6.3 × 6.7 ft |
| Frame (inside) | 76″ × 80″ | 193 × 203 cm | 6.3 × 6.7 ft |
| Frame (outside) | 79″ × 82″ | 201 × 208 cm | 6.6 × 6.8 ft |
| Minimum room | 144″ × 120″ | 366 × 305 cm | 12 × 10 ft |
| Floor space | — | — | 42.2 sq ft |
| Per-sleeper width | 38″ | 97 cm | 3.2 ft |
Quick check: if your current bed frame is 80″ long, it will fit a King, but measure the width — a King is 76″ across, and most Queen frames are 4–6 inches too narrow.
These figures match the standard dimensions in the Sleep Foundation’s mattress sizes guide, the reference most US retailers also publish against.
King vs Queen — Which Is Right for You?
A King is 16 inches wider than a Queen. That extra width is the main reason to upgrade: each sleeper gets the same personal space as a Twin XL bed. Queen and King are the same length (80″), so you aren’t buying extra legroom — only elbow room.
If you and your partner roll toward each other at night, or one of you is a restless sleeper, a King helps. If your bedroom is small, be honest about the footprint: a King takes up 42.2 sq ft of floor, versus 33.3 sq ft for a Queen. Compare all the sizes in our mattress sizes chart.
King Bed Frame Dimensions
A King mattress fits a frame that is typically 76″ × 80″ on the inside and around 79″ × 82″ on the outside, depending on the frame style. A standard Eastern King frame and a standard King frame are the same thing — “Eastern King” is just the full name for the 76″ × 80″ size.
When moving a King, measure your doorways: a King mattress is 76 inches wide, so it needs to go through doorways wider than that or be taken up as a split box spring. Most split King box springs are two 38″ × 80″ pieces.
Split King: Two Twin XLs on One Frame
A Split King is not a different footprint — it is a King built from two separate Twin XL mattresses, each 38″ × 80″, pushed together on a single King frame. The split exists for adjustable bases: each sleeper can raise their own head or feet, choose a different firmness, and move without rocking the other half of the bed. The trade-offs are a shallow valley where the halves meet (a bed bridge kit fills it), separate fitted sheets for each half unless you use one King flat sheet over both, and a higher total price than a single King mattress. If you are considering one, check each half’s thickness matches, so the two sleeping surfaces sit level.
Each half is a standard single bed in its own right — the Twin XL mattress size guide has its full dimensions, sheet sizes and dorm uses.
Dressing a bed this size costs more, so check the King row of our sheet sizes chart for the exact flat and fitted dimensions before you order bedding.
King vs California King
The California King is narrower and longer: 72″ × 84″. Price is similar. Choose a California King if you are taller than 6 feet 2 inches — the extra 4 inches of length matter more than width when your feet reach the end of the bed.
The full trade-off between the two — length, width, bedding and room shape — is covered on our dedicated California King size page.
For a second opinion on the same trade-off, the Sleep Foundation’s California King vs King comparison reaches the same conclusion: width for couples, length for tall sleepers.
What Room Size Does a King Bed Need?
A King bed needs a room of at least 12 × 10 feet, and 12 × 12 feet or bigger is more comfortable. That leaves roughly 24–30 inches of walking space on both sides and at the foot. In a 10 × 10 ft room a King technically fits, but there will be little room left for dressers or easy movement — a Queen (60″ × 80″) is the smarter choice there. Compare all sizes in our mattress sizes chart.
Still deciding whether the jump is worth it? Our Queen vs King comparison weighs the extra width against cost, room size and moving hassle.
Is a King Too Big for One Person?
Not necessarily. A King is a good fit for a single sleeper who likes to sprawl, works from bed with a laptop, or shares the bed with a child or a pet. The trade-off is the extra floor space — a King takes up roughly 42 sq ft, so it dominates a small room.
Before You Order: Check the Delivery Path
A one-piece King mattress is 76 inches wide and barely bends, so walk the route from the front door to the bedroom first. Note the narrowest doorway (standard interior doors are about 30–32 inches wide, so the mattress travels on its edge), any tight stairwell turn, and low landings. If the path fails, you have three honest options: a mattress-in-a-box King which arrives compressed in a carton roughly 40–45 inches long; a Split King, whose halves are ordinary Twin XL size and go anywhere; or a split foundation under a standard mattress, which solves the base even when the mattress itself fits.
Not sure the King is your size at all? Run your room and sleeper numbers through our mattress size guide and finder for a straight recommendation.
Related Mattress Size Guides
- California King Size Bed Dimensions — 72″ × 84″, the longer option
- Queen Size Mattress Dimensions — 60″ × 80″, the step down
- Queen vs King — the head-to-head decision
- Mattress Size Guide & Finder — three questions, one answer
Frequently Asked Questions
What are the dimensions of a king size bed?
A standard king size bed is 76 × 80 inches (193 × 203 cm). A California King is 72 × 84 inches.
How much bigger is a King than a Queen?
A King is 16 inches wider than a Queen, at 76 inches versus 60 inches. Both are 80 inches long.
Will a king fit in a 10 × 10 room?
It fits, but with only about 24 inches of space around it. For comfort, choose at least a 12 × 10 foot room, with 12 × 12 ft or bigger being ideal.
Do two twin XL beds make a King?
Yes, two Twin XL mattresses (38 × 80 inches each) placed side by side make a standard King. That setup is called a Split King, and it works well with adjustable bases.
What frame size do I need for a King mattress?
A King frame is normally 76 × 80 inches on the inside, with the outside measuring about 79 × 82 inches depending on the frame.
Is California King bigger than King?
No. A California King (72 × 84 in) is longer but narrower than a standard King (76 × 80 in), so it actually has slightly less surface area.
Sources: Sleep Foundation — Mattress Sizes guide; Sleep Foundation — California King vs King.