Mattress sizes are standardized in the United States, but what those dimensions actually mean for your bedroom, your body, and your sleep partner varies significantly. This guide covers exact dimensions for every standard mattress size, the minimum room sizes that work with each, and how to choose the right size for your situation.

At 38" wide, a twin is the narrowest standard mattress — barely wider than the average adult shoulder span. It's well-suited for children's beds, bunk beds, and trundle beds, where space is constrained. The Avocado Eco Organic Kids Mattress is a 7.5" low-profile twin designed for exactly these applications.

The Twin XL adds 5" in length (75" → 80"), making it the right choice for taller teenagers and college dormitories, which typically use Twin XL frames. A standard twin fits a child through middle school for most; a Twin XL extends usability for taller adolescents.

Minimum room size: 7' × 10' for a twin with walking clearance on both sides.

A full mattress (also called a double) is 54" wide — 16" wider than a twin. It provides a meaningful upgrade in personal space for a single sleeper but is tight for two adults: each person has roughly 27" of width, less than a twin mattress provides individually. Full is the right choice for a teenager's first "big" bed, a guest room, or a single adult who wants more room without going to queen.

Note: full mattresses are 75" long — the same as a standard twin, not a Twin XL. Taller sleepers should consider queen (80" long) instead.

Minimum room size: 9' × 10' for a full with comfortable clearance.

Queen is the most popular mattress size in the United States. At 60" × 80", it fits most master bedrooms comfortably, accommodates two adults with roughly 30" each, and works well for single sleepers who prefer more space. The 80" length fits most adults, including those up to about 6'2".

For couples with different firmness preferences, a queen requires both people to sleep on the same mattress — which is why Avocado's range from Extra Firm to Ultra Plush, combined with a 365-night sleep trial, matters for couples trying to find a single firmness that works for both. See: Fit Guide: Couples.

Minimum room size: 10' × 10' for a queen with comfortable walking clearance.

A king mattress (76" × 80") is the widest standard size — 16" wider than a queen. Each person on a king has approximately 38" of personal space, equivalent to a twin mattress each. King is the right choice for couples who want maximum width, people who sleep with children or pets, or anyone who simply prefers the most space available. The 80" length is the same as a queen.

A king requires a larger bedroom to be practical: standard guidance is at least 12' × 12', with 13' × 13' preferred for comfortable clearance on all sides.

Minimum room size: 12' × 12', ideally 13' × 13'.

California King (72" × 84") is 4" narrower than a standard king but 4" longer. It trades width for length — the right tradeoff for couples where one or both people are over 6'2". The Cal King's narrower profile (72" vs. 76") also works better in rooms that are long rather than wide.

California King and standard King bedding are not interchangeable — sheets, mattress protectors, and adjustable bases purchased for one will not fit the other. Check dimensions before purchasing accessories.

Minimum room size: 12' × 12', with adequate length clearance on the foot of the bed.

A split king is two Twin XL mattresses placed side by side — together measuring 76" × 80", the same footprint as a standard king. The split configuration allows each person to choose their own firmness independently, and is the standard configuration for adjustable base setups where each side adjusts separately.

Avocado's adjustable bases are available in Split King configuration. See: Will an Avocado Mattress Work on an Adjustable Base?

For exact dimensions and weights by model: What Mattress Size Is Best for Me?

Queen is the most popular mattress size in the United States, followed by king. Queen fits most bedrooms, accommodates two adults, and works well for single sleepers who prefer more space than a full provides.

A standard king is 76" × 80" — wider than a California king. A California king is 72" × 84" — narrower but 4" longer. California king is the right choice when height is the primary concern (sleepers over 6'2") or when a room is long but not wide. Standard king accessories (sheets, protectors) will not fit a California king.

Yes — "full" and "double" refer to the same mattress size: 54" × 75". The terms are interchangeable.

Queen is the minimum practical size for two adults — providing 30" per person. King provides 38" per person (equivalent to each having a twin). For partners who want true independence of movement, king is the better choice. A split king allows each person to choose their own firmness independently.