Mattress Size Guide: Which Size Do I Need?

Answer three quick questions and this guide will recommend the right mattress size for the way you sleep — then explain why, with the exact dimensions. If you would rather browse, the full mattress sizes chart lists every size in inches, feet and centimeters.

Find Your Mattress Size

Mattress Sizes Chart

Size	Inches	CM	Feet
Twin	38″ × 75″	97 × 191 cm	3.2 × 6.3 ft
Twin XL	38″ × 80″	97 × 203 cm	3.2 × 6.7 ft
Full / Double	54″ × 75″	137 × 191 cm	4.5 × 6.3 ft
Queen	60″ × 80″	152 × 203 cm	5.0 × 6.7 ft
King	76″ × 80″	193 × 203 cm	6.3 × 6.7 ft
California King	72″ × 84″	183 × 213 cm	6.0 × 7.0 ft

How Mattress Sizes Work

US mattress sizes are standardized: Twin 38″ × 75″, Twin XL 38″ × 80″, Full 54″ × 75″, Queen 60″ × 80″, King 76″ × 80″ and California King 72″ × 84″. Choosing between them comes down to three things only — how many people share the bed, how tall they are, and how big the room is. That is exactly what the finder above weighs up.

The nursery end of the chart follows safety rules rather than preference: see our crib mattress size guide for the regulated 28″ × 52″ standard.

All Mattress Sizes at a Glance

Two patterns in the table drive almost every decision. Length comes in only two adult standards — 75 inches (Twin, Full) and 80 inches (Twin XL, Queen, King) — with the California King’s 84 inches as the exception. And width per sleeper, not total width, is what your body actually notices at 3 a.m.

The dimensions in this table match the standard figures published in the Sleep Foundation’s mattress sizes guide.

Three Rules of Thumb

• Length: the mattress should be at least 6 inches longer than the tallest sleeper. Over 6 ft tall → look at 80-inch sizes (Twin XL, Queen, King); over 6 ft 4 in → California King.
• Width per person: 27″ (Full) is a squeeze, 30″ (Queen) is comfortable for most couples, 38″ (King) is spacious.
• Room: keep 24–30 inches of walking space around the bed. Queen needs ~10 × 10 ft; King needs ~12 × 12 ft.
• Future-proofing: growing teenagers and couples rarely regret sizing up once.

The Fourth Factor: How You Sleep

The finder weighs sleepers, height and room — but your sleep position quietly changes the width you need. Back sleepers: stay centred and are comfortable in the least width. Side sleepers: curl and shift, using a little more. Stomach sleepers and restless combination sleepers sprawl — arms out, legs angled — and are the ones who feel a Queen’s 30 inches as a limit and a King’s 38 inches as freedom. If one partner sprawls and the other does not, size for the sprawler: a couple where either person is a restless sleeper should treat the King as the default whenever the room allows it, and couples who both sleep still and close often find the Queen genuinely cosier rather than merely cheaper.

For the single-sleeper end of the scale, the Twin XL guide explains when 80 inches of length matters more than extra width.

The Sleep Foundation’s mattress shopping guide makes the same point we build this finder on: size should be decided from sleepers, height and room before any other feature.

Check the Room With Painter’s Tape (10 Minutes)

Before ordering, test the footprint for real. Mark the bed’s outline on the floor with painter’s tape — mattress size plus about 2 inches on each side for the frame. Then live around the outline for a day: open the wardrobe and every drawer, swing the door fully, make the “bed” with an armful of laundry, and walk the route you take at night. If you are squeezing past the tape or a drawer stops halfway, the size is too big no matter what a chart says. If the outline looks lost in the room, you have honest room to size up.

Furnishing a camper instead of a bedroom? None of these sizes apply directly — use our RV mattress sizes chart for short queens, bunks and three-quarter sizes.

Once you have picked a size, our sheet sizes chart gives you the flat and fitted sheet dimensions to dress it.

And before you order furniture, check the bed frame sizes chart — the frame will be bigger than the mattress it holds.

Most shoppers narrow it down to two sizes. Our head-to-head guides settle the common debates: Full vs Queen and Queen vs King. For individual sizes, start with the Queen and King dimension pages — and for the individual sizes themselves, work through the Twin, Full and California King dimension pages alongside the Queen and King pages linked there.

Related Mattress Size Guides

• Twin Size Mattress Dimensions — 38″ × 75″
• Twin XL Mattress Size — 38″ × 80″
• Full Size Mattress Dimensions — 54″ × 75″
• Queen Size Mattress Dimensions — 60″ × 80″
• King Size Bed Dimensions — 76″ × 80″
• California King Size Bed Dimensions — 72″ × 84″

Frequently Asked Questions

What mattress size should I get?
For one adult, a Full or Queen. For couples, a Queen suits most rooms and a King suits rooms 12 × 12 ft or larger. Use the finder above for a recommendation based on your height and room.

What is the most popular mattress size?
The Queen (60″ × 80″) is the best-selling size in the US.

Is it better to size up a mattress?
If the room fits it and the budget allows, yes — extra width is the comfort factor couples notice most, and a mattress lasts 7–10 years.

What size bed do I need for a small apartment?
A Full (54″ × 75″) is the usual answer for one person; a Twin XL saves more space while keeping full adult length.

Sources: Sleep Foundation — Mattress Sizes guide; Sleep Foundation — Mattress Shopping guide