A reliable way to size a mattress protector is to measure your own mattress and compare the numbers with the product page. Bed names such as twin or queen are a starting point, but makers' measurements can differ a little, and depth varies more than length or width. This guide shows what to measure and where to find the matching details in a listing.
Why the mattress label is the place to start
Check the mattress itself for a tag or label. Some list the size name and the dimensions. If there is none, a tape measure does the job, and a minute of measuring prevents a protector that will not stay on or will not zip.
Write down length, width and depth in both inches and centimetres. Canadian listings use either, and some give both. To convert, multiply inches by 2.54 to get centimetres, or divide centimetres by 2.54 to get inches.
Keep the tape straight and flat against the mattress, without pressing into it. Measure twice, since a small error can change which size fits.
Canadian bed size names and how they are used
Many retailers use twin and single for the same size, and double and full for the same size. The table gives approximate sizes. Makers vary, so treat these as a rough guide only. A twin, for example, may be listed at 38 or 39 inches wide, and a double at 53 or 54.
| Name | About (inches) | About (cm) |
|---|---|---|
| Twin or single | 39 x 75 | 99 x 191 |
| Twin XL | 39 x 80 | 99 x 203 |
| Double or full | 54 x 75 | 137 x 191 |
| Queen | 60 x 80 | 152 x 203 |
| King | 76 x 80 | 193 x 203 |
Children's beds, care beds and campers can have their own sizes. If a nurse or occupational therapist set up a care bed or a special mattress, ask them before you add a cover to it.
The Mattress Protector Zipper Vinyl 36" x 80" x 6.5" lists three measurements instead of a size name. The Universal Mattress Cover with Defined Perimeter, Fits 42" Width - 1 Each names a width. Neither uses twin or queen, which shows why you should compare numbers.
Twin XL, split king and other in-between sizes
Twin XL has the same width as a twin but is longer. It turns up on adjustable beds and in student residences, and a twin protector is likely to be too short for it.
A split king is two twin XL mattresses side by side. If the halves move separately on an adjustable base, each half needs its own twin XL protector. If they stay flat together, one king protector over both is another option. Check whether a listing is for a single half or for the full bed.
The Vinyl Mattress Protector, Zippered, Twin is named for a twin. If your bed is twin XL, confirm the length on the product page before you buy.
Measuring mattress depth for the right pocket
Fitted-style protectors have a pocket, like a fitted sheet. The pocket depth in the listing should be at least as deep as your mattress. A pocket that is too shallow pulls the corners off, and one that is far too deep bunches.
- Lay the tape at the side of the mattress, from the bottom edge to the top surface.
- For a pillow-top, measure at the highest point without pressing down hard.
- Write the number in the same units the listing uses.
A zippered encasement should match all three measurements, since it wraps the whole mattress.
Toppers, pillow-tops and adjustable bases
If you use a topper, decide where the protector goes. If it goes over the topper, measure the mattress and topper together. If it goes under, measure the mattress alone and check how the topper will be covered.
Adjustable bases flex in the middle, so look for a listing that mentions them. Fitted styles with more stretch can have more room for small errors, while a rigid encasement has less.
What to do when your mattress is between sizes
- Compare the listing's mattress range with your measurements, in both inches and centimetres.
- If your measurement falls between two sizes, choose the one whose range includes it.
- Do not pick a much larger size to be safe, since a baggy cover wrinkles and shifts.
- When in doubt, send us your measurements.
Where sizing details appear on the product page
Look in the title, the description and any size chart. A listing may give a bed name, a set of measurements or both. These are the details to find:
- which number is the width, which is the length and which is the depth;
- whether the depth is the protector's pocket or the deepest mattress it fits;
- whether the numbers are in inches, centimetres or both;
- whether a zippered style is sized by the mattress it fits or by the cover itself.
If a listing gives a pocket depth, a length and a width, match all three. If a number is missing, ask before you order.
While you work out the protector size, a bed pad can cover part of the bed. See our washable underpads and bed pads.
Shop this guide
- Bedlore Waterproof Mattress Protector Crib 2 Pack, Gray
- Vinyl Zippered Crib Mattress Cover Full Encasement 28in x 52in Standard Size Waterproof White
- BEDLORE 2 Pack Queen Waterproof Mattress Protector,Deep Pocket 6"-18",White
- Crib Sheets Set, 52″×28″ Baby Mattress Covers, 2pc Solid & Printed Set, Magical Forest
- See all: Waterproof Mattress & Furniture Protectors
Prices are on each product page. Free shipping on orders of $100 or more within Canada.
Common questions
Is a twin protector the same as a single?
Many retailers use the names for the same size. Check the dimensions in the listing to be sure.
Should I take the bedding off before I measure?
Yes. Sheets, pads and an old protector add height and hide the corners, so measure the bare mattress. Include a topper only if it will sit inside the new protector.
Does a thick topper change the size I need?
It can. A fitted protector that goes over a topper needs a deeper pocket, so measure the mattress and topper together.
Will a queen protector fit a double bed?
It will be loose. A queen is wider and longer than a double, so a queen protector is likely to bunch and shift on a double mattress. Choose the size that matches your measurements.
If your measurements fall between sizes, send them through our contact page and we will reply within one business day.