Buying a bed starts with one number: the size. Get it right and the mattress, frame and sheets all fall into place; get it wrong and you are returning a Queen because it swallowed a small bedroom. This is our plain-English reference to every standard US bed size in 2026 — the exact dimensions in inches and centimeters, the room each one needs, and who each size actually suits.
Bookmark this page. If you are shopping for a specific product, jump to our guides on bed frames, budget mattresses under $300 or adjustable beds. Below, a few mattresses that ship in nearly every size, so once you know your dimensions you can buy with confidence.
Popular Mattresses in Every Size
Nectar Memory Foam Mattress
- Available Twin through Cal King
- Medium-firm suits most sleepers
- Long trial and warranty
Lucid 10-Inch Memory Foam Mattress
- Every size from Twin to Cal King
- Gel foam sleeps a touch cooler
- Wallet-friendly
Novilla 12-Inch Gel Memory Foam Mattress
- Good motion isolation
- Available in larger couple sizes
- Bouncy comfort layer
Sweetnight Breeze 12-Inch Mattress
- Two firmness sides
- Full size range
- Gel-infused cooling
Zinus Green Tea Memory Foam Mattress
- Cheapest per size
- Twin XL and split-king friendly
- Multiple thickness options
Full mattress dimensions chart
These are the standard US mattress dimensions. Actual products vary by an inch or so, but sheets and frames are built to these numbers.
| Size | Dimensions (inches) | Dimensions (cm) | Best for |
|---|---|---|---|
| Crib / Toddler | 28 x 52 | 71 x 132 | Infants and toddlers; fits standard cribs and toddler beds |
| Twin | 38 x 75 | 96.5 x 190.5 | Kids, bunk beds, small guest rooms |
| Twin XL | 38 x 80 | 96.5 x 203 | Taller teens, dorms, and split-king setups |
| Full / Double | 54 x 75 | 137 x 190.5 | Solo adults who want room to spread out; tight for couples |
| Queen | 60 x 80 | 152 x 203 | Most couples and single adults; the best-selling size |
| King | 76 x 80 | 193 x 203 | Couples who want space, or share the bed with kids or pets |
| California King | 72 x 84 | 183 x 213.5 | Tall sleepers who value length over width |
How to match a bed size to your room
A mattress needs walking room around it — aim for at least 24 inches (about 60 cm) of clearance on the sides you use to get in and out, plus space for nightstands and open doors or closets.
- Under 10 x 10 ft (3 x 3 m): Twin or Full. A Queen fits but leaves little floor space.
- 10 x 10 to 10 x 12 ft: Queen is the sweet spot — room for two side tables and easy walkways.
- 12 x 12 ft (3.7 x 3.7 m) and up: King or California King without crowding the room.
If your room is long and narrow, a California King (longer but narrower than a standard King) can fit better than you would expect while still giving tall sleepers the extra length.
King vs. California King
They hold almost the same square footage but in different shapes. A standard King is 4 inches wider and 4 inches shorter than a California King. Choose a King if width matters most — co-sleeping with kids or pets, or two people who like their space side to side. Choose a California King if height is the priority: anyone over about 6’2″ will appreciate the extra 4 inches of length. Note that Cal King sheets and frames are a separate size, so factor that into cost.
Do two twins make a king?
Almost, and this trips people up. Two Twin XL mattresses placed side by side measure 76 x 80 inches — exactly a standard King. That is what a “split king” is, and it is the reason adjustable bases for couples use two Twin XL mattresses: each person can raise or lower their own side. Two regular Twins do not equal a King — they come up short at 76 x 75 inches, and each partner would sleep 5 inches shorter than a King allows.
Sizes for kids and growing families
A crib mattress (28 x 52 in) carries a child from newborn through the toddler bed stage, since standard toddler beds reuse the same size. From there, most kids move to a Twin — the size used in almost every bunk bed. Buying a Twin XL early can save an upgrade for a child who is likely to grow tall.
What size should you actually buy?
- Solo adult, average room: Queen. It is the default for a reason.
- Couple: King if you have the floor space, Queen if you do not.
- Guest room or dorm: Twin XL — fits most bodies without dominating the room.
- Tall sleeper: California King, or any “XL” length option.
- Child: Twin now, or Twin XL to grow into.
Once you have your number, browse boxed options in our mattress reviews or start with our roundup of the best bunk beds if you are outfitting a kids’ room.
Ready to shop your size?
These best-selling boxed mattresses ship in nearly every size from Twin to California King.
Check price on AmazonDo two twin beds make a king?
Two Twin XL mattresses side by side equal a standard King (76 x 80 inches) — that is a split king. Two regular Twins fall short at 76 x 75 inches.
What is the most popular bed size?
The Queen (60 x 80 inches) is the best-selling size in the US, fitting most couples and single adults in an average bedroom.
What is the difference between King and California King?
A standard King is wider (76 in) and a California King is longer (84 in). Pick King for width, Cal King for length if you are tall.
What size mattress does a toddler bed use?
Standard toddler beds and cribs both use a 28 x 52 inch crib mattress, so one mattress covers both stages.
How much room do I need around a Queen bed?
Aim for at least 24 inches of walking space on the sides you use, so a Queen is comfortable in a room of about 10 x 10 feet or larger.
Nadia Whitfield
Nadia Whitfield is TalkBeds' Sleep Science Editor. A sleep researcher and science writer by background, she is the reason our sleep and health claims can be trusted. While our testers focus on how a mattress feels, Nadia focuses on what the evidence… Full profile & sources →