🛏️ Bedding Size Calculator
Choose your mattress size and depth and the calculator gives you the exact cut dimensions for fitted sheets, flat sheets, and duvet covers, plus the fabric yardage a duvet cover needs — piecing in extra widths automatically when your cloth is narrower than the cover.
🔧 Size Your Bed Linen
What is a Bedding Size Calculator?
A bedding size calculator turns your mattress dimensions into the cut sizes you need to sew your own bed linen. You choose a mattress size and tell it the depth, and it works out how big to cut a fitted sheet, a flat sheet, and a duvet cover so each one fits properly once it's hemmed and finished.
The dimensions aren't guesses — they apply standard home-sewing allowances. Fitted sheets wrap the mattress depth on every side with a tuck-and-elastic margin; flat sheets add generous hems and tuck; duvet covers add ease so the insert sits comfortably without straining the seams. Change the depth and every figure adjusts, because a slim mattress and a deep pillow-top need very different sheets.
Beyond the cut sizes, it calculates how much fabric a duvet cover takes. If your fabric is wide enough, the panels come from single widths; if it's narrower than the cover, the calculator pieces in extra widths and reports the larger yardage honestly. Sewing your own bedding lets you choose the exact fabric, fit, and finish — and getting the sizes right is the foundation of a result that looks and feels shop-bought.
📖 How to Use the Bedding Size Calculator
1Pick Your Mattress Size
Select your mattress from the list — twin, twin XL, full, queen, king, or California king. Each option shows the standard length and width in inches, so you can confirm it matches your bed.
If your mattress is an unusual size or an international standard that isn't listed, measure its length and width directly and use the closest match as a reference for adjusting the figures.
2Measure the Mattress Depth
Enter the depth — the side height of the mattress — in inches. This is the single most important custom measurement, because it determines how far a fitted sheet has to wrap down each side to grip properly.
Measure your actual mattress rather than guessing; depths range from around 6 inches for a slim mattress to 16 or more for a pillow-top, and a sheet cut for the wrong depth either floats loose or refuses to stay on.
3Set Your Fabric Width
Tell the calculator how wide your fabric is. Wide quilting cotton runs up to 108 inches and can make a duvet panel from a single width, while standard 44-inch cotton will need piecing for larger covers.
The tool checks this width against the duvet panel size and automatically pieces in extra widths when the fabric is too narrow, so the yardage it reports reflects the fabric you'll actually buy.
4Read Your Cut Sizes and Yardage
The calculator returns the cut dimensions for a fitted sheet, a flat sheet, and a duvet cover, plus the fabric yardage needed to make the duvet cover. Cut your panels to these sizes, then hem and finish as your pattern directs.
Always pre-wash and dry your fabric before cutting so any shrinkage happens first — bedding is laundered constantly, and a pre-shrunk fabric keeps the fit you measured for wash after wash.
💡 Practical Bedding Tips
- Measure depth yourself: Mattress depth varies most between beds, so always measure rather than assume
- Pre-wash everything: Bedding is washed constantly, so shrink the fabric before cutting, not after
- Go wide for duvets: 108-inch quilting cotton avoids piecing seams across a duvet cover
- Choose the right weave: Percale sleeps crisp and cool; sateen feels smooth and warm — pick to suit the sleeper
- Add good elastic: Quality all-round elastic keeps a fitted sheet gripping a deep mattress through every wash
- Mind directional prints: If your fabric has a one-way pattern, plan panels so the motif runs the right way up
🎯 Benefits of Sizing Bedding Correctly
📏 A Proper, Lasting Fit
Cut sizes that account for your exact mattress depth give fitted sheets that grip and stay on, and covers that sit smoothly over the insert instead of pulling tight or bagging loose.
🧵 Buy the Right Fabric Amount
The duvet-cover yardage tells you precisely how much to buy — and pieces in extra widths automatically — so you avoid both running short and over-buying expensive sheeting.
🎨 Total Freedom of Choice
Sewing your own bedding means you pick the exact fibre, weave, colour, and weight, instead of settling for whatever the shops happen to stock this season.
💷 Save on Premium Linen
Quality linen and high-thread-count cotton bedding is expensive to buy finished; making your own from yardage can cost far less for the same lovely fabric.
🛠️ Fits Odd-Sized Beds
Antique frames, bespoke mattresses, and international sizes rarely match shop bedding; calculated cut sizes let you make linen that fits a bed off-the-rack sheets won't.
♻️ Repair and Replace Singly
Knowing the exact cut sizes lets you remake just the worn-out fitted sheet or flat sheet, extending the life of a set instead of replacing the whole lot.
❓ Frequently Asked Questions
Why does mattress depth matter so much when sewing a fitted sheet?
A fitted sheet has to wrap not just the top of the mattress but its full depth on all four sides, plus enough extra to tuck under and hold with elastic. Mattress depths vary enormously — a slim guest mattress might be 6 inches while a pillow-top can exceed 16 — so a sheet cut for one will either float loose or pop off the other. This calculator adds twice the depth (top side plus the opposite side) along both the length and width, then a tuck-and-elastic margin, so the finished sheet grips a mattress of the depth you actually measured rather than a generic assumption.
How are standard mattress sizes defined, and are they the same everywhere?
The calculator uses the common North American mattress dimensions: twin 75×38, twin XL 80×38, full 75×54, queen 80×60, king 80×76, and California king 84×72 inches. These are nominal sizes — actual mattresses vary by an inch or so between brands, and depth varies far more. Sizing also differs internationally; a UK king or a European queen won't match these figures. Because real mattresses differ, the safest practice is to measure your specific mattress — length, width, and depth — and treat the standard figures as a fallback when you can't measure.
How much fabric does a duvet cover need, and why might it require piecing?
A duvet cover is essentially two large panels sewn together, each cut a little larger than the finished cover for seam allowances. If your fabric is wide enough — wide quilting cotton runs up to 108 inches — each panel comes from a single width and you simply buy twice the panel length. But standard 44-inch quilting cotton is far narrower than a queen or king cover, so each panel must be pieced from two or three fabric widths sewn together, multiplying the yardage. The calculator detects this automatically: it checks your fabric width against the panel width and pieces extra widths in when needed, so the yardage it reports is honest for the fabric you're actually using.
Should I pre-wash fabric before sewing bedding, and how does that affect sizing?
Yes — always pre-wash and dry bedding fabric before cutting. Cotton and linen sheeting can shrink several percent on the first wash, and since bedding is laundered constantly, an unwashed sheet sewn to exact size will shrink to a poor fit after its first trip through the machine. Pre-washing lets the fabric shrink before you cut, so your finished dimensions hold up. The allowances this calculator builds in are generous enough to absorb minor variation, but they assume a stable, pre-shrunk fabric; skipping the pre-wash undoes that safety margin and risks sheets that no longer tuck or covers that pull tight over the insert.