| Quick Facts | |
|---|---|
| Twin topper | 38 x 75 in |
| Twin XL topper | 38 x 80 in |
| Full / double topper | 53 x 75 in |
| Queen topper | 60 x 80 in |
| King topper | 76 x 80 in |
| California king topper | 72 x 84 in |
The mattress topper size chart, in inches
A mattress topper comes in six standard sizes that mirror US mattress dimensions, from twin at 38 by 75 inches up to California king at 72 by 84.
Shopping for a specific model? See the best mattress topper we tested — 10 models compared on the specs that decide it.
Every topper on the market is built to drop onto an existing mattress, so the sizing borrows the mattress chart wholesale. Six footprints cover nearly every bed sold in the United States. A twin topper measures 38 by 75 inches, the smallest of the group and the one made for a child's room or a single adult bed. Twin XL keeps that same 38-inch width but stretches to 80 inches long, which is why it turns up in college dorms and on adjustable frames where the extra length matters.
Full, sometimes labeled double, widens things to 53 by 75 inches without adding any length over a regular twin. Queen is the volume seller at 60 by 80 inches, and king is the widest at 76 by 80. California king rounds out the mattress topper size chart at 72 by 84 inches, trading a little width for extra length. These figures come from the Better Sleep Council, the consumer-education arm of the International Sleep Products Association, and topper makers cut to them almost without exception.
The practical takeaway is short. Read the size printed on your mattress law tag, or measure the bed corner to corner, and buy the topper with the matching name. There is no separate topper sizing to learn on top of the mattress sizes you already know.
Why topper sizes follow the mattress, not a separate standard
Topper dimensions copy mattress dimensions by industry convention; no federal rule sets a topper size, and the flammability standard at 16 CFR part 1632 does not mention toppers at all.
It is fair to ask who decides these numbers. The short answer is the mattress industry itself, working through trade groups rather than a government agency. The Better Sleep Council publishes the dimensions most retailers follow, and because a topper is defined entirely by the bed it sits on, its size chart is just the mattress chart with a different label on the package.
Federal regulation touches bedding in a narrow way. The flammability standard at 16 CFR part 1632, enforced by the Consumer Product Safety Commission, defines a mattress as a ticking filled with resilient material meant for sleeping upon, and a mattress pad as a thin, flat cushion for use on top of a mattress. Both fall inside the rule. The word topper never appears in it. A thick foam comfort layer sits in a gray zone between a pad and a mattress, and the standard was not written with it in mind.
That gap matters less for sizing than it might sound, because the footprint is settled by the mattress convention regardless. What it does mean is that the mattress topper size chart carries no federal weight behind its numbers. They hold because manufacturers all cut to the same well-known dimensions, and a topper that ignored them simply would not sell.
Twin, twin XL, and full: the smaller footprints
The three smallest sizes share short widths: twin and twin XL are both 38 inches wide, and full is 53, with twin XL adding length for taller beds.
The narrow end of the chart trips people up more than the big beds do, because three sizes cluster close together. Twin and twin XL are identical in width at 38 inches; the only difference is the five inches of length twin XL adds, reaching 80 inches instead of 75. That gap sounds trivial until a topper meant for a 75-inch bed leaves five inches of an 80-inch dorm mattress bare at the foot. If you are outfitting a single bed and want to compare specific models, our twin mattress topper guide sorts them by fill and feel rather than size alone.
Full, or double, jumps to 53 by 75 inches. It is fifteen inches wider than a twin but no longer, which surprises couples who assume a full gives them meaningfully more room to stretch out. It does not; it gives them width to share. A twin topper on a full mattress leaves a strip of bare bed down one side, so the size names are not interchangeable even though the lengths line up. Shoppers weighing a full for a guest room or a shared bed can start with our full mattress topper guide, which lays out the options at that footprint. Get the width right first, then worry about thickness and material.
Queen, king, and California king: the wider beds
The three largest sizes are queen at 60 by 80 inches, king at 76 by 80, and California king at 72 by 84, which is narrower but longer than a standard king.
Queen is the size most people picture and the one most toppers are made in first. At 60 by 80 inches it fits the mattress that dominates US bedrooms, wide enough for two but not sprawling. If a queen is what you are topping, our queen mattress topper guide is organized around that footprint. King moves up to 76 by 80 inches, the widest bed on the chart, adding sixteen inches across without changing the length. Two sleepers get close to a twin's worth of personal width each, which is the whole appeal of a king, and our king mattress topper guide covers the models cut to fit it.
California king is where buyers slip up most. It is not bigger than a king across the board. At 72 by 84 inches it is actually four inches narrower than a standard king but four inches longer, built for tall sleepers who run out of bed before they run out of room to the sides. The two are not interchangeable in either direction. A king topper hangs off the foot of a Cal king and falls short at the edges, while a Cal king topper does the reverse. When a bed is this large, measuring once before you order saves a return later.
How to measure your bed and choose a topper size
Measure the mattress width and length before buying, match those to a name on the mattress topper size chart, and treat thickness as a separate choice from footprint.
When the size on the tag has rubbed off, or the mattress came without one, a tape measure settles it. Measure the sleeping surface flat, corner to corner, ignoring any pillow-top bulge, and compare the width and length against the chart. Width is the number that usually decides the size name, since several beds share the same 75- or 80-inch lengths.
Two wrinkles are worth flagging. Deep mattresses and an existing pad do not change which topper size you need; footprint is footprint, and a topper is sized to the sleeping surface, not to how tall the mattress stands. Thickness is the genuinely separate decision. A topper's loft, whether it is a shallow two inches or a plush four, changes how soft the bed feels but has nothing to do with where it lands on the mattress topper size chart. Pick the footprint from the chart, then pick the thickness from how firm your mattress currently sleeps.
One last case worth knowing: split kings. Adjustable bases that bend each side independently use two twin XL toppers rather than one king, so a couple can raise one half without dragging the other along. If that is your setup, buy the pair by the twin XL measurement, not the king.