What size duvet do you need, and how much overhang will you get once you are in bed?

The six seller pages we read listed queen duvets and covers anywhere from 88 to 98 inches wide. The chart on the bag also assumes a flat, empty mattress. Yours has depth. At least one person sleeps in it.

This guide is for: people in the United States choosing a duvet or insert for a twin, full, queen, king or California king bed, and anyone whose duvet looks short once it is on the bed.

What size duvet fits each US mattress?

A queen mattress is 60 by 80 inches and most queen duvets run 88 to 98 inches wide, so the size name alone tells you less than the width does.

Start with the mattress. Its size is the one fixed number in your bedroom. Avocado's size guide lists six standard US sizes: Twin (38" x 75"), Twin XL (38" x 80"), Full (54" x 75"), Queen (60" x 80"), King (76" x 80"), and California King (72" x 84"). Serta's copy of the ISPA dimension standard lets a finished mattress vary by half an inch either way.

Duvets have no such standard. Each seller picks its own width, and many sell a single "full/queen" size for both beds. Tuft & Needle lists its inserts at 68 inches wide for Twin/Twin XL, 98 for Full/Queen and 116 for King/Cal King. So the same duvet gives a full bed more overhang than a queen.

The table pairs each mattress with duvet widths that sellers list for their own products. The last column is plain subtraction.

The duvet widths come from each seller's own page: Qbedding, Tuft & Needle, Westex and Beddley.

Go by the width, not the name. Every duvet width above is on a seller's own page, so you can check it before you buy.

How much overhang does a duvet give on each side?

Subtract the mattress width from the duvet width and halve it. That is your overhang per side with nobody in the bed, and it is the best case.

The arithmetic is short. Subtract the mattress width from the duvet width, then halve the result. A 90-inch duvet on a 60-inch queen leaves 15 inches hanging on each side. A 106-inch duvet on a 76-inch king leaves the same 15 inches.

Those 15 inches assume nobody is in the bed. They also assume the duvet lies flat and dead center. It drifts after the first night.

Length works differently, and you seldom run short there. You do not pull a duvet over your pillows.

A standard pillow is 20" x 26" (Nest Bedding), and it lies with its short side running down the bed.

So on an 80-inch queen, about 60 inches of mattress sits below the pillows. A duvet 90 inches long covers that. It still has about 30 inches to spare at the foot, which is enough for even a deep mattress.

The sides are where you run short. They have to cover the full depth of the mattress, and they are the part your body pulls on. If your duvet looks fine at the foot but shows the mattress along the sides, the width is too small. The next two sections show where those side inches go and how many you need.

What overhang does nobody account for?

Your body lifts the duvet off the mattress. Each sleeper takes back several inches of width, so the overhang you see in a shop shrinks at night.

Charts are drawn for an empty bed. Once you lie down, the duvet rises over your body. Then it comes back down. That climb uses width that would otherwise hang over the edge.

How much width? A peer-reviewed study of US adults used 2011–2012 national survey data to measure abdominal height with people lying on their backs. The median was 21.9 cm, and men measured higher than women.

That median converts to about 8.6 inches. We assume each sleeper takes back about 9 inches of width. That is the median rounded up. The duvet climbs over the body and back down, but it tents between two people rather than hugging each one.

This table is our arithmetic, not a measurement. No maker publishes it. What matters is the gap between the columns. A couple under a 90-inch queen duvet keeps about 6 inches per side, roughly half the side of a standard mattress. If you sleep on your side or share with a restless partner, you pull harder than that, and the mattress edge shows on whichever side loses.

How deep is your mattress, and why does it change the size?

Most mattresses are 10 to 12 inches deep, and the duvet has to drop that far on each side before it covers the edge you can see from the door.

Depth is the number you skip. The Sleep Foundation says the average mattress ranges from 8 to 14 inches tall, and a standard 10 to 12 inches suits most adults. It counts 14 inches and up as extra-thick, and some mattresses reach upward of 20 inches.

To hide the side of your mattress, the overhang on each side has to at least match the depth. A topper you add counts too. So a 12-inch mattress with a 2-inch topper needs 14 inches per side before anyone climbs in.

Put depth and sleepers together and you get the width to shop for: mattress width, plus twice the depth, plus about 9 inches per sleeper.

You should read these as our judgement figures, built on the 9-inch assumption above. They explain a common complaint. A couple on a 12-inch king needs a duvet close to 118 inches wide.

The widest king insert we found listed was 116 inches (Tuft & Needle).

If your king duvet looks skimpy, the numbers agree with you.

How much do queen duvets vary from one seller to the next?

Across six seller pages we read, queen duvets ran from 88 to 98 inches wide. That 10-inch spread is 5 inches of overhang on each side.

We read six seller pages on September 26, 2026, each listing the width of its own queen or full/queen duvet insert or cover. No width here is a measurement of ours. We copied the figure each page prints, sorted the pages into three width buckets, and set out the counting rules on our method page.

The six pages are Qbedding, Gracious Style's Sferra listing, Cotton Metrics on Amazon, Mellanni, Casper and Tuft & Needle.

You can see the count is small and the split is even. That even split is the finding. Two duvets sold under the same name can differ by 10 inches, which is 5 inches of overhang per side.

Southshore Fine Linens, a linen seller, makes the same point: one brand's queen insert might be 90" x 94", while another is 88" x 92".

Covers add a second variable. You will usually buy the insert and the cover separately. A cover cut for a 98-inch insert hangs loose around an 88-inch one. Write down both numbers before you order. Our page on what goes inside a cotton duvet insert explains how the fill changes the way a given width drapes.

What sizes do queen and king cotton comforters come in?

Cotton comforter pages we read sold queens at 88 to 92 inches wide and kings at 104 to 108, which leaves about 14 to 16 inches a side.

We read 7 product pages on September 26, 2026, each selling a queen or king comforter with a cotton shell. You will find comforters sized as loosely as inserts. Queen widths ran from 88 to 92 inches under one size name, and lengths ran from 88 to 96. King widths ran from 104 to 108.

Puredown lists its Full/Queen at 88 by 90 inches. Crane & Canopy gives 90 by 94 for its queen and 108 by 94 for one King/Cal King size. L.L.Bean lists 88 by 96 and 107 by 96. The Whisper Organics king on Natural Linens is 104 by 92.

Now do the subtraction. Take 76 from 104 and 28 inches are left, or 14 on each side. From 108 you get 16. A king comforter hangs about as far down each side as a queen does on its own bed. On a California king, a one-size King/Cal King gives you a little more width. You lose about 4 inches at the foot.

Watch for Full/Queen as well. Most of these pages sell you one size for two beds. A full mattress is 54 by 75 inches (Sleep Advisor), narrower and shorter than a queen. So the same comforter hangs long on a full and can come up short on a deep queen. Read the width and the length before you read the size name.

Should you size up to a king duvet on a queen bed?

A king duvet on a queen bed adds about 8 inches on each side. It suits couples and deep mattresses, but it can reach the floor on a low frame.

Often, yes. It helps most when two of you share the bed. Westex lists its king down duvets at 106 x 90 inches.

On a 60-inch queen that gives 23 inches per side on an empty bed. A 90-inch queen gives 15. With two sleepers, the table earlier puts you at about 14 inches per side. That covers a 12-inch mattress.

The floor sets the limit. NapLab puts the average bed at 24 to 25 inches from the floor to the top of the mattress, and calls beds of 11 inches or less low-profile.

A 23-inch drop clears a standard bed but will pool on a low platform. On a low frame, an oversized queen is the smaller step up.

Three checks before you size up:

• Cover: a king insert needs a king cover. Casper advises a cover the same size as the insert or around two inches shorter.
• Length: the Westex king is the same length as a typical queen, so what you gain is width.
• Warmth: more fabric and fill makes a heavier, warmer duvet, so if you run hot, pick a lighter fill in the bigger size.

Is a king on a queen a style choice? Partly. It is also the most direct fix for the width sleepers take back. If the extra warmth worries you, our guide to summer and year-round weights shows how much fill a lighter weight leaves out.

Does a cotton duvet shrink enough to matter?

Cotton shells can shrink a few percent in the first hot wash. On a 90-inch duvet, 5 percent is 4.5 inches, which is over 2 inches per side.

It can, and the loss comes out of the side overhang you counted on. Southshore Fine Linens, citing Online Clothing Study, says cotton can shrink anywhere from two to seven percent, depending on the quality of the fabric and construction. On your bed, that means the duvet edge sits higher up the side of the mattress after the first hot wash.

Apply that range to a 90-inch queen. Two percent costs 1.8 inches of width and seven percent costs 6.3 inches, about 1 to 3 inches per side. With two sleepers, a queen may start with only 6 inches per side, so one hot wash can leave you and your partner with half of that.

Preshrunk or prewashed bedding helps you, because its maker has taken some of this shrinkage out first. The fill can move too. One batting seller says washing usually shrinks cotton batting by about 3 to 5% (Fanda Fabrics). One comforter seller advises line drying or low heat to avoid shrinkage (Natural Linens).

On a 92-inch cotton-filled comforter, that batting range is roughly 2.8 to 4.6 inches of width. Wash cold and dry low for the first several washes, and measure the duvet flat after its first wash. Our guide to washing a cotton duvet covers the washer size it needs and how to dry it through.

If you are between two sizes, shrinkage is one more reason to take the larger one. A duvet that starts an inch or two too wide ends up about right. One that starts exactly right ends up short.

How do you measure your bed before you buy?

Measure width and depth with the bedding off. You want a duvet wider than the mattress by twice its depth plus about 9 inches per sleeper.

Strip the bed down to the fitted sheet. Find a soft tape measure. Five minutes gets you every number this guide uses.

1. Width: measure straight across the top of the mattress, edge to edge. Expect 38, 54, 60, 72 or 76 inches.
2. Depth: measure from the bottom of the mattress to the top of its quilted surface, at the middle of one side. Include any topper.
3. Floor clearance: measure from the floor to the top of the mattress. Keep your overhang a few inches shorter than that.
4. Sleepers: count everyone who sleeps under this duvet most nights, including a child who climbs in.

Then do the sum: width, plus twice the depth, plus 9 inches per sleeper. That total is the duvet width to shop for. Compare it with the width printed on the seller's page, not with the size name.

The Sleep Foundation gives a shorter rule for an empty bed: "multiply the measured mattress height by two and add it to the measured width." It covers the mattress sides but leaves out you and your partner. Treat it as the floor.

Say you share a 60-inch queen that is 11 inches deep. That comes to 60 plus 22 plus 18, or 100 inches. A 90-inch queen falls short. A 106-inch king covers it with room left over. You know which one to buy before you open a single product page.

Common questions

Short answers on full/queen sizes, covers, centimeters, European 200 cm duvets, twin sizes and one King/Cal King size for two beds.

Is a full/queen duvet the same size as a queen duvet?

Usually, yes. Casper says its full and queen duvets are the same size, 95 by 98 inches. Other sellers cut theirs from 88 to 98 inches wide, so read the width. On a full bed, which is narrower than a queen, the same duvet hangs about 3 inches lower on each side.

Will a queen duvet fit inside an 88 by 92 inch duvet cover?

An insert of about 88 inches will. A 98-inch insert would be squeezed and bunch at the edges. Tuft & Needle makes its cover a few inches smaller than its insert so the insert keeps its shape.

What are queen duvet dimensions in inches and in centimeters?

The queen pages we read ran 88 to 98 inches wide, about 224 to 249 cm. Casper's queen is 95 by 98 inches (241 by 249 cm).

Is a 200 x 200 cm duvet the same as a US queen?

No. A 200 cm duvet is about 79 inches wide, roughly 9 inches narrower than the narrowest US queen we read. On a 60-inch queen it leaves about 9 inches per side before anyone gets in.

What size is a twin or single duvet in the US?

US twin duvets run about 66 to 68 inches wide. Tuft & Needle lists its Twin/Twin XL insert at 68 by 88 inches, which leaves 15 inches per side on a 38-inch twin.

Is a king duvet big enough for a California king duvet cover?

Usually, because most sellers cut one King/Cal King size for both beds. A Cal King mattress is 72 inches wide, 4 narrower than a king, so the same duvet hangs 2 inches lower on each side. Check the cover's width against the insert's before you order.

Choose these answers in the weight finder and it suggests two cotton duvets of different weights, for partners who run hot and cold.