Mattress Size Table
| Size | Inches (W × L) | Centimeters (W × L) | Notes |
|---|---|---|---|
| Crib | 27.5 × 52 | 70 × 132 | Standard crib, toddler beds |
| Cot / Small Single | 30 × 75 | 76 × 191 | Day beds, narrow guest beds |
| Twin or Single | 38.5 × 74.5 | 98 × 189 | Single sleeper, kids rooms |
| Twin XL | 38.5 × 79.5 | 98 × 202 | College dorms; two make a split King |
| Full or Double | 53.5 × 74.5 | 136 × 189 | Single upgrade, snug for two |
| Full XL | 53.5 × 79.5 | 136 × 202 | Taller single sleepers |
| Queen | 60 × 79.5 | 152 × 202 | Standard couples choice |
| Super / Olympic Queen | 66 × 80 | 168 × 203 | Wider Queen niche size |
| King | 76 × 79.5 | 193 × 202 | Maximum standard width |
| California King | 72 × 83.5 | 183 × 212 | Longer and narrower, tall sleepers |
US mattress names describe a role, not a measurement - Twin, Full, Queen, King - and the numbers behind them are close but not round: a Queen is 60 by 79.5 inches, not 60 by 80, and a King is 76 wide, not 72 like its Californian cousin. The chart below carries the exact figures in inches and centimeters for the six standard adult sizes plus the specialty sizes that keep surprising second-time buyers: the crib and cot sizes, the Full XL that dorms and adjustable beds use, and the Olympic Queen that fills the gap nobody names. Bedding is sold against these exact numbers, so measuring with the chart open is the difference between a fitted sheet that tucks and one that snaps off at 3 a.m.
Three patterns organize the ladder. Width steps go 38.5, 53.5, 60, 76 inches - each adult step up buys real elbow room for two sleepers, which is why couples start at Queen. Length stays at 74.5 inches for the standard tier and 79.5 for the XL tier - the XL add-on exists because the standard bed is shorter than many adults are tall, and five inches of extra length is the whole difference. And California King is not a bigger King but a differently shaped one: six inches narrower and four inches longer, built for tall sleepers and long narrow bedrooms. Nobody who measures once ever mixes them up again - which is the point of having the table open while shopping.
How to use
- Measure the space and the sleeper before the name: add the width of everyone sleeping in it (a couple needs at least 60 inches of Queen, more if either is a spread-out sleeper), and check the length against the tallest person plus about four inches.
- Match the mattress to the frame exactly - the chart numbers are the mattress, and frames, box springs and fitted sheets are cut to the same figures with minimal slack: a Half-inch mismatch reads as a sagging edge or a sheet that will not stay on.
- For tall sleepers look down the length column: 79.5-inch tiers (Twin XL, Queen, King) fit most adults; the 74.5-inch standard tier (Twin, Full) runs short past six feet, and the 83.5-inch California King is the longest mainstream option.
Frequently asked questions
Do two Twin mattresses equal a King?
Almost - and the missing piece is length, not width. Two standard Twins side by side give about 77 inches of width against the King's 76: close enough. But a standard Twin is 74.5 inches long against the King's 79.5 - five inches of gap at the foot. The trick that actually works is two Twin XLs: at 38.5 x 79.5 each, they combine to 77 x 79.5, which matches a King mattress almost exactly - which is why hotel split-King setups are built from two Twin XLs on one base, each side adjustable independently. The same arithmetic explains the split-Queen and split-Cal-King specialty sizes in the adjustable-bed market. If you already own two standard Twins and want the width, expect the foot gap and either buy a King-length blanket or accept cold feet; if you are buying fresh for a split setup, Twin XL is the pairing the industry actually standardized on.
What is the real difference between a California King and a regular King?
Shape, not size. The regular King is 76 by 79.5 inches - four inches wider, four inches shorter; the California King is 72 by 83.5 inches - narrower and longer, trading reach-across room for foot room. Total area is nearly identical, so neither is objectively bigger; the Cal King suits sleepers over about six foot two who want their feet off the footboard, and fits long narrow master bedrooms where a regular King would block a walkway. The practical catch is bedding: King sheets fit Cal Kings badly - a 76-inch-wide flat sheet on a 72-inch mattress is loose across the width and four inches short at the foot, and fitted sheets will simply not seat. Every sheet, protector and bed frame in the Cal King line is a separate SKU, usually pricier and always less stocked. Measure the bedroom first, the sleepers second, and only then argue about the name.
Is a Full bed big enough for two adults?
Barely, and both sleepers have to be polite about it. A Full (Double) gives each adult 26.75 inches of width - roughly the shoulder width of the mattress a single sleeper gets on a Twin, with zero margin for sprawl, pets, or a child who migrates in at 2 a.m. For comparison, a Queen gives each person 30 inches and a King 38. Sleep surveys and the mattress trade converge on the same advice: couples who start on a Full usually step up to a Queen within a couple of years, and the Full size survives mostly as the single-sleeper upgrade (a step up from Twin for taller adults or guest rooms). Where a Full genuinely works for two: small bodies, a studio apartment where the bed is also the sofa, or a couple who sleeps apart by preference - the European-style separate duvets help on any width. The chart numbers make the trade visible: upgrading Full to Queen buys 6.5 inches of width for 79.5 inches of the same length.
Why do dorms use Twin XL instead of Twin?
One measurement: 79.5 inches versus 74.5. College-age adults average taller than the 1950s population the standard Twin was sized for, and a 74.5-inch mattress leaves under four inches of margin for a six-footer - feet off the end. The XL adds five inches of length on the same 38.5-inch width, fits the same narrow dorm rooms and the same standard doorway, and - the facilities manager's real motive - works for everyone without stocking two lengths. The same size doubled is the split-King pairing, so a dorm veteran already owns the raw material for an adjustable King later. The shopping trap is bedding: a standard Twin fitted sheet stretches over a Twin XL with a visible gap at the foot or simply does not seat - Twin XL bedding is a distinct, clearly labeled size, worth checking twice in the cart.