How to measure for a mattress (and your bed frame and room)
Hi, we’re John and Mimi. Before you order a mattress, five minutes with a tape measure saves a lot of headaches: the wrong size, a bed that sits too high, sheets that won’t stay on, or a frame that leaves a gap. Here’s exactly what to measure, in what order, and how to turn those numbers into the right size and thickness.
The short answer
- Measure the mattress you have: width, length and height (thickness), in inches, across the top and at the edge.
- Match the width and length to a standard size using the chart below. Twin and Twin XL are the same width, and king and cal king are easy to mix up, so check the length too.
- Measure inside the bed frame, rail to rail and headboard to footboard. The mattress should fill it without big gaps.
- Measure the room: a common rule of thumb is about 2 feet of walking space on each side and at the foot of the bed.
- Measure from the floor to the top of the mattress you sleep on now. That number tells you how thick the new one should be on your frame.
What you need
A tape measure (a metal one stays straight across a wide bed), something to write on or your phone, and ideally a helper to hold the other end. Take the sheets and mattress pad off first so you measure the mattress, not the bedding. Write every number down in inches.
Step 1: Measure your mattress
- Width: across the top, side to side, through the middle of the mattress.
- Length: from the head end to the foot end, down the middle.
- Height (thickness): from the bottom seam to the top, at the edge rather than the middle, where an older mattress may have sagged.
Round to the nearest inch and compare with the chart. A mattress can run up to about an inch smaller or larger than its standard size depending on the model, and listings sometimes round: our own Express Mattress Foundation lists a twin as 38" × 74" and a Twin XL as 38" × 79". A reading within an inch or so of a standard size is that size.
| If you measure about | It’s a | Easy to confuse with |
|---|---|---|
| 38" × 75" | Twin | Twin XL (same width, 5" longer) |
| 38" × 80" | Twin XL | Twin; two Twin XLs side by side make a split king |
| 54" × 75" | Full (double) | Queen (6" wider, 5" longer) |
| 60" × 80" | Queen | Full |
| 76" × 80" | King | Cal king (4" narrower, 4" longer) |
| 72" × 84" | California king | King |
| Two halves, each 38" × 80" | Split king | King (same overall size) |
Every size in feet and inches is in our mattress size chart. Torn between two sizes? See twin vs Twin XL, full vs queen, queen vs king and king vs California king.
Numbers that don’t match any size? Sofa beds, some antique beds and some RV beds take mattresses that aren’t a standard size. Don’t guess: text John the measurements and a photo, and he’ll tell you honestly whether anything we carry fits.
Step 2: Measure your bed frame
- Inside width and length. Measure inside the frame, rail to rail and headboard to footboard, where the mattress will sit. It should be the mattress size or a touch bigger, never smaller.
- What holds the mattress up. Our mattress listings ask for “a continuously solid surface, an adjustable base, or slats no more than two (2) inches apart.” Measure the gap between the edges of two slats. If it’s wider than 2", see what to put under a memory foam mattress.
- How tall the side rails are. Measure from the slats or deck up to the top of the rail. A thin mattress can sink below the rails; a thicker one shows more above them.
- Bunk beds, trundles, daybeds and Murphy beds have a maximum mattress thickness on a label or in the manual. Use that number, not your eye. For trundles, measure from the trundle’s platform to the bottom of the bed above it and leave a little room so it rolls in. More in bunk beds, trundles and daybeds and best mattress for a Murphy bed.
- Putting an adjustable base inside your frame? Compare the inside of the frame with the base size and check that the side rails won’t block the moving parts. Our how to choose an adjustable base checklist and adjustable base with a headboard guide cover the details.
Shopping for a frame too? Our how to choose a bed frame guide compares every frame and foundation we sell.
Step 3: Measure the room
Measure the wall the headboard will go against and the distance from that wall to the opposite wall or furniture. Then add walking space. A common rule of thumb is about 2 feet on each side and at the foot of the bed. With that clearance, each size needs roughly this much floor:
| Size | Mattress | Floor with 2 ft on both sides and the foot | Against a wall (2 ft on one side) |
|---|---|---|---|
| Twin | 38" × 75" | 7'2" × 8'3" | 5'2" × 8'3" |
| Twin XL | 38" × 80" | 7'2" × 8'8" | 5'2" × 8'8" |
| Full | 54" × 75" | 8'6" × 8'3" | 6'6" × 8'3" |
| Queen | 60" × 80" | 9' × 8'8" | 7' × 8'8" |
| King | 76" × 80" | 10'4" × 8'8" | 8'4" × 8'8" |
| California king | 72" × 84" | 10' × 9' | 8' × 9' |
These are for the mattress alone. A frame, headboard or footboard adds a few inches, and nightstands add their own width. Also check that doors, closet doors and dresser drawers can open fully with the bed in place. A bed shared by two people every night is usually happiest with walking space on both sides.
Step 4: Measure the way in
Our mattresses ship compressed and rolled in a box for small-parcel delivery, so a new mattress rarely gets stuck on stairs or in a hallway (it expands once you open it in the room; see how long a mattress in a box takes to expand). Our upholstered bed frames are also listed as shipping in one box. If you’re bringing in anything bigger, or carrying out an old mattress, measure the narrowest doorway and the tightest stair turn first. A split king comes as two Twin XL halves, which are easier to carry than one king.
Step 5: Measure the height
Measure from the floor to the top of the mattress you sleep on now. Bed height is three numbers added together: the legs or frame, the foundation or base, and the mattress. Swap a 10" mattress for a 12" on the same frame and the bed sits 2" higher.
- A comfortable height: many people like to sit on the edge with their feet flat on the floor and their knees about level with their hips. Most people like the top of the mattress about knee height.
- What our listings give: the Express Mattress Foundation stands on 6" legs, and the e3 adjustable base lists screw-in legs at 3", 6", 9" or 12". Our mattresses run from 6" to 14" thick.
- Headboards: the Avery, Madison and Tufted frames list an adjustable height from 51 to 54 inches. Measure how much headboard shows above your mattress today, then plan the new mattress thickness around it.
More on choosing a thickness in how thick should a mattress be.
Step 6: Measure for sheets and a protector
Measure the mattress height with the protector or topper on, then check it against the pocket depth of the sheet and protector. Here is what our listings say:
| Product | Listed fit | Works with |
|---|---|---|
| Terry Cloth Mattress Protector | Up to an 11" mattress | Our 6", 8" and 10" mattresses |
| Quilted Cotton Mattress Protector | Up to an 11" mattress | Our 6", 8" and 10" mattresses |
| Premium Bamboo Mattress Protector | Up to a 16" mattress | Every mattress we sell, including 12" and 14" |
| Essentials Bedding Bundle | Fitted sheet with a 16" skirt; protector with a 16" pocket | Every mattress we sell |
Our bamboo sheet set listing doesn’t give a pocket depth, so for a 12" or 14" mattress text John and he’ll check. More in do you need a mattress protector and best sheets for an adjustable bed.
Our mattresses by thickness at today’s prices
Once you know the size and how tall the bed can be, pick a thickness. For example, the 10" Rose is $399 in queen today. One mattress in each thickness we carry, in the four most common sizes:
| Pick | Best for | Model code | Twin | Full | Queen | King |
|---|---|---|---|---|---|---|
| 6" Essentials Firm | Low profile for guest beds, bunks and trundles | 6ESS-T |
Sold out today | $299 | $309 | — |
| 8" Daisy Firm | Firm support on a budget | 8BNV-T |
$249 | $309 | $349 | $399 |
| 10" Rose Medium | Medium feel, washable cover | 10BNV-T |
$279 | $369 | $399 | $469 |
| 12" Copper Gel Memory Foam | Medium feel, our best-known copper model | 12BNCOPPER-TL |
— | $479 | $519 | $629 |
| 14" Ananda Pearl & Gel Plush | Extra-thick plush memory foam | 14PEARL-TL |
— | — | $729 | $809 |
Prices are today’s prices, read live from our catalog, with free FedEx shipping included. A dash means that model isn’t made in that size.
Every model, side by side, is on the mattress comparison chart.
10" Rose - Medium Firmness - 10BNV
A middle-of-the-road 10" height that suits most frames, with a medium feel and a washable cover. Comes in every standard size.
- 10" tall, medium feel
- Twin through cal king
- Ships compressed and rolled in a box
From $279 (Twin) · Queen $399 · See sizes & details
Express Mattress Foundation with 6" Grey Wood-Style Legs
Measured and found you have nothing to put the mattress on? A foundation with wood slats on its own 6" legs that can stand alone as the bed.
- Twin through cal king
- 6" legs, wood slats
- No tools to assemble
From $259 (Twin) · Queen $279 · See sizes & details
Shop this guide
Got your numbers? These three cover most beds.
- 10" Rose - Medium Firmness - 10BNV, from $279. Medium 10" mattress in every standard size.
- Express Mattress Foundation with 6" Grey Wood-Style Legs, from $259. Foundation on 6" legs; stands alone, no tools.
- Premium Bamboo Viscose Mattress Protector - Waterproof & Hypoallergenic, from $60. Waterproof protector that fits mattresses up to 16".
Questions we hear a lot
How do you measure a mattress?
Take the bedding off and measure in inches: width across the top through the middle, length from head to foot down the middle, and height from the bottom seam to the top at the edge. Round to the nearest inch and match the width and length to a standard size, such as 60 by 80 inches for a queen.
How do I know what size my bed frame is?
Measure inside the frame, rail to rail and headboard to footboard, where the mattress sits. Compare that with the standard sizes: twin 38 by 75, Twin XL 38 by 80, full 54 by 75, queen 60 by 80, king 76 by 80 and California king 72 by 84 inches. The inside should be the mattress size or a touch bigger.
How much room do you need around a bed?
A common rule of thumb is about 2 feet of walking space on each side and at the foot of the bed. With that clearance a queen needs roughly 9 by 8 feet 8 inches of floor and a king roughly 10 feet 4 inches by 8 feet 8 inches, before adding the frame, headboard and nightstands.
My mattress measures 74 inches, not 75. What size is it?
A twin or a full. A mattress can run up to about an inch smaller or larger than its standard size depending on the model, and some listings round down. If your numbers are more than an inch or two off every standard size, it may be a sofa bed, antique or RV size, so text John the measurements at 818-924-3744 before you order.
How thick should my new mattress be for my bed frame?
Measure from the floor to the top of the mattress you have now. Bed height is the legs or frame, plus the foundation or base, plus the mattress, so a 12 inch mattress sits 2 inches higher than a 10 inch on the same frame. Bunk beds, trundles, daybeds and Murphy beds have a maximum thickness on the label; stay at or under it.
Send us your numbers
Text John the width, length and height of your mattress, the inside of your frame and the size of the room (a photo helps), and he’ll tell you honestly which size and thickness fit. Text or call 818-924-3744, 6 AM to 9 PM Pacific, take the 60-second mattress quiz, or start with our how to choose a mattress checklist. See our Purchase Policy & Warranty for the details.
Written by John & Mimi Venti, MimiJohn. Standard US mattress dimensions; room clearance and bed height are rules of thumb; frame, foundation, base and protector numbers are from our product listings; prices are read live from our catalog and update automatically.