Mattress by Size: Complete Mattress Size Chart and Buying Guide

Updated: June 30, 2026

Mattress by size means choosing a mattress based on standard dimensions such as Twin, Twin XL, Full, Queen, King, California King, and Split King. The right size depends on the number of sleepers, sleeper height, bedroom space, and whether the mattress is for a child, single adult, couple, guest room, family, or adjustable bed setup.

The standard U.S. mattress sizes are Twin, Twin XL, Full/Double, Queen, King, California King, and Split King. Use the chart below to compare mattress dimensions in inches and centimeters, then choose the size that fits your body, room, and sleep needs.

If you are unsure, Queen is usually the safest default for adults because it works for many single sleepers, couples, guest rooms, and standard bedrooms. If you share the bed and have enough space, King is the best upgrade for width. If you are tall, California King is the best upgrade for length.

Once you know the right size, use the links below to browse mattresses by category.

To choose the right mattress size, start with four factors:

1. Number of sleepers: one person, couple, child, guest, or family.
2. Sleeper height: taller sleepers usually need 80 inches or more of length.
3. Bedroom size: the mattress should leave room for walking and furniture.
4. Sleep style: restless sleepers and couples often need more width.

A child or single sleeper may be comfortable on a Twin, Twin XL, or Full. Most couples should start with a Queen. Couples who want more personal space should consider a King. Tall sleepers should consider Twin XL, Queen, King, or California King because these sizes offer more length than a standard Twin or Full.

Length matters most when the sleeper's feet hang off the bed or touch the footboard. Twin and Full mattresses are usually 75 inches long, while Twin XL, Queen, and King are usually 80 inches long. California King is usually 84 inches long.

The best mattress size should fit the sleeper and still leave enough room for walking, nightstands, closet doors, dressers, and other furniture.

A mattress may technically fit in a room but still feel too large if it blocks drawers, doors, or walking space. For comfort, measure the full room layout before buying, not just the wall where the bed will sit.

Recommended visual asset: add a scaled top-down diagram comparing Twin, Twin XL, Full, Queen, King, California King, and Split King.

Suggested image alt text:
“Mattress size comparison chart showing Twin, Twin XL, Full, Queen, King, California King, and Split King dimensions.”

Suggested caption:
“Mattress sizes compared by width and length. King offers the most width, while California King offers the most length.”

This visual should appear near the main size chart to support image search, improve user experience, and make size differences easier to understand at a glance.

A Twin mattress usually measures 38 inches wide by 75 inches long. It is the smallest common standard mattress size for one sleeper.

Choose a Twin mattress for children, teenagers, bunk beds, trundle beds, daybeds, and narrow rooms. Avoid a Twin if the sleeper is tall, shares the bed, or wants extra space to stretch out.

Twin mattress dimensions

A Twin XL mattress usually measures 38 inches wide by 80 inches long. It has the same width as a Twin but adds about 5 inches of length.

Choose a Twin XL mattress for taller single sleepers, dorm rooms, narrow rooms, and adjustable Split King setups. It is a good choice when you need more legroom but do not have enough room for a Full or Queen.

Twin vs Twin XL

A Full mattress, also called a Double, usually measures 54 inches wide by 75 inches long. It is wider than Twin and Twin XL, but shorter and narrower than Queen.

Choose a Full mattress for solo adults, teenagers, small apartments, and guest rooms. A Full can fit two adults, but it usually feels cramped for regular nightly use because each sleeper gets limited width.

Full mattress dimensions

A Queen mattress usually measures 60 inches wide by 80 inches long. It is one of the most versatile mattress sizes because it balances sleeping space, cost, and room fit.

Choose a Queen mattress if you sleep with a partner, want more room as a single sleeper, or need a mattress for a primary bedroom that is not large enough for a King. Queen also works well in guest rooms because it can fit one or two sleepers.

Queen mattress dimensions

A King mattress usually measures 76 inches wide by 80 inches long. It gives couples the most width among common standard mattress sizes.

Choose a King mattress if you share your bed and want more personal space, if one or both sleepers move around at night, or if children or pets sometimes join the bed. A King gives each sleeper about the same width as a Twin mattress when two people share the bed.

King mattress dimensions

A California King mattress usually measures 72 inches wide by 84 inches long. It is longer than a standard King but slightly narrower.

Choose a California King if you or your partner are tall, if your bedroom is longer than it is wide, or if legroom matters more than shoulder room. Choose a standard King instead if you want the widest common mattress size.

California King mattress dimensions

A Split King usually measures 76 inches wide by 80 inches long in total and is commonly made from two Twin XL mattresses, each measuring 38 inches by 80 inches.

Choose a Split King if you and your partner want separate mattress movement, different firmness levels, or an adjustable base where each side can move independently. Split King is especially useful for couples with different sleep preferences.

King vs Split King

Mattress size affects more than the mattress itself. Once you choose a size, you also need compatible sheets, mattress protectors, bed frames, foundations, adjustable bases, and comforters.

Sheet size compatibility

Bed frame compatibility

A King mattress and a California King mattress are not interchangeable. King is wider, while California King is longer, so each needs its own matching frame and bedding.

Mattress depth and deep-pocket sheets

Mattress height can affect sheet fit even when the mattress size is correct. If your mattress is thick, has a pillow top, or uses a mattress topper, choose deep-pocket or extra-deep-pocket sheets that match both the size and depth of the mattress.

Mattress size names are not the same in every country. A “King” in the U.S. may not match a “King” in the U.K. or Europe. Always check exact dimensions before buying an imported mattress, bed frame, or bedding.

Check both inches and centimeters when buying across countries or mixing a mattress, frame, and bedding from different regions.

Most shoppers choose Twin, Twin XL, Full, Queen, King, California King, or Split King. However, some situations require specialty sizes.

Specialty sizes can be harder to find and may require custom sheets, protectors, or frames. Always verify the exact dimensions before buying accessories.

The best mattress size depends on your body, room, and sleeping arrangement.

If you are choosing between two sizes, choose the larger size only if your room can support it comfortably. The right mattress should improve sleep without making the room harder to use.

Hand-picked guides on the things that go around the mattress, from sheets and toppers to bedroom sets and seasonal gear. These open in a new tab.

• images/sleeping-bags.jpg 4:3 Choosing a sleeping bag for warmth and packability
• images/outdoor-chaise-lounge.jpg 4:3 Outdoor chaise loungers for the patio and poolside
• images/throw-pillows-for-couch.jpg 4:3 Styling a couch with throw pillows
• images/king-size-bedroom-sets.jpg 4:3 Putting together a king-size bedroom set
• images/queen-mattress-topper.jpg 4:3 How a mattress topper changes comfort and feel
• images/silk-sheets.jpg 4:3 A closer look at silk and other sheet fabrics
• images/green-duvet-cover.jpg 4:3 Picking a duvet cover color for the bedroom
• images/how-to-deep-clean-a-mattress.jpg 4:3 A guide to deep-cleaning your mattress
• images/king-comforter-sets.jpg 4:3 Coordinating a king comforter set
• images/best-rated-pregnancy-pillows.jpg 4:3 Finding a supportive pregnancy pillow