Pick your bed, measure the mattress and say how far the covers should hang. You get the comforter or duvet size to buy, in inches, and the fitted-sheet pocket depth.
Comforter to buy
Queen comforter, 86–90″ widehangs 13–15″ down each side of a 12″ mattress · fitted sheets: deep pocket
Quick answer: comforter sizes are not a standard, so buy by the inches. A comforter must be the mattress width plus twice the drop you want down each side. On a 12″ queen mattress that is 84″ wide, and every queen comforter (86–90″) covers it. Past a box spring, or with a deep pillow top, size up: an oversized queen, or a king.
How to use the bedding size calculator
- Pick your bed size and measure the mattress from its bottom seam to its highest point, topper included.
- Say how far the covers should hang: just over the mattress sides, past the box spring or bed frame, or all the way to the floor like a bedspread. For the last two, add the box spring height or the height of the mattress top off the floor.
- The answer is the comforter or duvet size to buy, with the width and length to look for on the label, how far it will hang, and the fitted-sheet pocket depth. Copy link keeps it for the shop.
The rule: mattress width plus twice the drop
The drop is how far a comforter hangs past the top edge of the mattress. To cover the mattress sides, the drop is the mattress depth. To hide a box spring or a frame rail too, add its height. To reach the floor, the drop is the height of the mattress top, less about an inch. A comforter needs the mattress width + 2 × the drop, so a 60″-wide queen mattress 12″ deep needs 60 + 24 = 84″.
The width is what decides the size. The foot depends on where the top edge sits: at the head of the mattress, a comforter hangs its length minus the mattress length at the foot; pulled up over the pillows, less.
Comforter sizes: two guides, two answers
Brands cut their own sizes, and the published guides disagree. The calculator uses the whole spread the two report, so “always” means even the smallest comforter of that name is wide enough.
| Size | Mattress | Sleep Foundation | Nectar |
|---|---|---|---|
| Twin | 38 × 75″ | 66–68 × 86–90″ | 66–68 × 86–88″ |
| Twin XL | 38 × 80″ | 68 × 86–90″ | 68 × 90″ |
| Full | 54 × 75″ | 78–88 × 86–92″ | 81–84 × 86–88″ |
| Queen | 60 × 80″ | 86–90 × 90–100″ | 86–88 × 96–100″ |
| King | 76 × 80″ | 90–108 × 86–108″ | 102 × 86–88″ |
| California king | 72 × 84″ | 90–110 × 92–108″ | 107–110 × 96–98″ |
An oversized queen is 98 × 98″, against a standard queen’s 90 × 90″ (Puffy). Oversized kings have no standard at all: shops make them wider and longer than their own kings, so check the inches against the width the calculator gives.
What size comforter to buy for each bed
For a 12″ mattress, the most common depth, and a 9″ box spring:
| Bed | Over the mattress | Past a 9″ box spring |
|---|---|---|
| Twin | twin, 62″+ wide | full, 80″+ wide |
| Twin XL | twin XL, 62″+ wide | full, 80″+ wide |
| Full | full, 78″+ wide | oversized queen, 96″+ wide |
| Queen | queen, 84″+ wide | king, 102″+ wide |
| King | king, 100″+ wide | bedspread, 118″+ wide |
| California king | California king, 96″+ wide | bedspread, 114″+ wide |
Fitted sheets: the pocket depth
Buy a fitted sheet whose pocket is 2–3″ deeper than the mattress with its topper. A pocket that only just matches stretches to its limit and the corners pop off. Sova’s classes:
| Depth | For a mattress (with topper) up to | |
|---|---|---|
| Standard pocket | 7–12″ | 10″ |
| Deep pocket | 14–17″ | 15″ |
| Extra-deep pocket | 18–22″ | 20″ |
Four worked examples
A queen, 12″ mattress, covers over the sides. It needs 60 + 2 × 12 = 84″ of width. Every queen comforter is 86–90″ wide, so buy a queen: it hangs 13–15″ each side. Sheets: a deep pocket, 14″ or more.
A queen with a 14″ pillow top. It needs 88″. Only the wider queens (88–90″) are enough, so check the label, or buy an oversized queen at 98″.
A full bed, 12″ mattress on a 9″ box spring, covers past it. The drop is 21″, so it needs 54 + 42 = 96″. No full or standard queen is that wide; an oversized queen (98″) is, and hangs 22″ each side.
A king, 12″ mattress on a 9″ box spring. It needs 118″, wider than any comforter in either guide. That is a bedspread or coverlet, or a bed skirt to cover the box spring, with an ordinary king comforter on top.
Common bedding size mistakes
- Buying by the name on the package. One brand’s queen is 86″ wide, another’s 90″. Compare the inches with the width you need.
- Forgetting the topper. A 3″ topper on a 12″ mattress makes it 15″: the comforter needs 6″ more width and the sheets a deeper pocket.
- A comforter the same size as the mattress. A mattress-sized comforter covers the top and nothing else. The drop is the whole point.
- Fitted sheets exactly as deep as the mattress. Leave 2–3″ extra so the elastic can grip under it.
- A duvet cover and insert of different sizes. The insert should match the cover’s label, or it bunches in a big cover and gets squeezed flat in a small one.
Dressing the whole bed? The throw pillow size calculator picks the pillows and the throw blanket size calculator the throw for the foot of it. Plan the bedroom in the free 2D room planner.
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Bedding size questions
What size is a king comforter?
It depends on the brand: the Sleep Foundation lists king comforters from 90 to 108″ wide and 86 to 108″ long, Nectar 102 × 86–88″. On a 12″ king mattress a comforter needs to be at least 100″ wide to cover the sides.
What size comforter for a queen bed?
A queen comforter, 86–90″ wide, covers the sides of a queen mattress up to about 13″ deep. For a deeper mattress or to hide the box spring, buy an oversized queen (98 × 98″) or a king.
What size comforter for a king bed?
A king comforter at least 100″ wide for a 12″ mattress. King comforters are sold from 90″ wide, so check the label; to hide the box spring too, you need a bedspread or a bed skirt.
What are the dimensions of a queen comforter?
About 86–90″ wide and 90–100″ long: the Sleep Foundation gives 86–90 × 90–100″ and Nectar 86–88 × 96–100″. A queen mattress is 60 × 80″.
What is an oversized king comforter?
A king comforter made wider and longer than the shop’s own standard king, for deep mattresses and high beds. There is no standard size, so compare its inches with what your bed needs: the mattress width plus twice the drop.
What are deep pocket sheets?
Fitted sheets with a pocket of 14–17″ (Sova), for mattresses from about 11 to 15″ deep. Extra-deep pockets, 18–22″, fit pillow tops and mattresses with a topper. Buy a pocket 2–3″ deeper than the mattress.
What size duvet for a king bed?
The same rule as a comforter: at least the mattress width plus twice the drop, 100″ wide for a 12″ king mattress. Buy the insert that size and a cover with the same label.