A lot of people buy a Texas King bed thinking the hardest part will be getting it through the door. The real challenge comes after: finding flat sheets that actually fit.
This bed is big — longer and wider than almost anything else on the market. And with that size comes more variables: pocket depth, box foundations, pillow tops, or custom frames. Regular king-size flat sheets? Not even close. Try putting them on, and you’ll either be tugging to make the corners fit or watching excess fabric puddle on the floor.
At the heart of the problem is this: the size of your mattress isn’t just about length and width. The pocket depth matters just as much — and whether you want your flat sheets to cover just the mattress or drape over the box spring too. If you get the dimensions wrong by even a few inches, your bedding won’t lie flat or look clean. And unfortunately, not all Texas King mattresses are the same pocket depth.
How Deep Is a Texas King Mattress?
The Texas King bed is a custom-sized mattress measuring 80 x 98 inches (203 x 249 cm) — longer than a California King, wider than a Standard King. But its pocket depth can vary a lot depending on the brand and build.
Here’s what you’ll see from popular brands that offer Texas King sizes:
| Brand Name | Mattress Size (inches) | Common Pocket Depths | Box/Foundation Included? |
| Helix Sleep | 80 x 98 | 12″, 14″, 16″ | No |
| Saatva | 80 x 98 | 13″, 15″, 17″ | Optional Box Spring |
| Big Fig | 80 x 98 | 13″, 15″, 17″ | Yes |
| Texas Mattress Makers | 80 x 98 | 12″, 14″, 16″ | No |
| Hästens | Custom sizes | 10″–17″ + box base | Yes, integrated foundation |
So before you order any flat sheets, make sure you know what kind of structure you’re working with. A thick mattress plus a tall base can easily push your total bed pocket depth above 20 inches.
How Do You Calculate the Right Flat Sheet Size?
It’s not just about covering the surface. A properly sized flat sheet should:
- Drape evenly over both sides
- Fully cover the foot of the bed
- Look smooth and tailored, not short or oversized
Let’s use centimeters here for precision.
Flat Sheet Size Formula (Metric):
- Sheet Width = Mattress Width + (2 × Mattress Pocket Depth) + 20 cm
→ This gives you about 10 cm of extra drape on each side - Sheet Length = Mattress Length + (2 × Mattress Pocket Depth) – 10 cm
→ We subtract a bit from the head, since that side usually sits against a headboard
Example:
Say you have a standard Texas King mattress:
- 203 x 249 cm
- 35 cm pocket depth
Then:
- Width = 203 + (2 × 35) + 20 = 293 cm
- Length = 249 + (2 × 35) – 10 = 309 cm
Your ideal flat sheet size would be 293 x 309 cm.
Recommended Flat Sheet Sizes by Mattress Pocket Depth (Metric)
| Mattress Pocket Depth | Width Formula | Length Formula | Final Flat Sheet Size (W × L) |
| 25 cm | 203 + 2×25 + 20 = 273 cm | 249 + 2×25 – 10 = 289 cm | 273 x 289 cm |
| 30 cm | 203 + 2×30 + 20 = 283 cm | 249 + 2×30 – 10 = 299 cm | 283 x 299 cm |
| 35 cm | 203 + 2×35 + 20 = 293 cm | 249 + 2×35 – 10 = 309 cm | 293 x 309 cm |
| 40 cm | 203 + 2×40 + 20 = 303 cm | 249 + 2×40 – 10 = 319 cm | 303 x 319 cm |
| 45 cm | 203 + 2×45 + 20 = 313 cm | 249 + 2×45 – 10 = 329 cm | 313 x 329 cm |
Prefer Inches? Here’s the Same Rule
Flat Sheet Size Formula (Imperial):
- Sheet Width = Mattress Width + (2 × Pocket Depth) + 8 inches
- Sheet Length = Mattress Length + (2 × Pocket Depth) – 4 inches
Examples:
Mattress: 80″ x 98″, Pocket Depth: 14″
- Width = 80 + (2 × 14) + 8 = 116 inches
- Length = 98 + (2 × 14) – 4 = 122 inches
Flat sheet: 116″ x 122″
Recommended Flat Sheet Sizes by Mattress Pocket Depth (Inches)
| Mattress Pocket Depth | Width Formula | Length Formula | Final Flat Sheet Size (W × L) |
| 10″ | 80 + 20 + 8 = 108″ | 98 + 20 – 4 = 114″ | 108″ x 114″ |
| 12″ | 80 + 24 + 8 = 112″ | 98 + 24 – 4 = 118″ | 112″ x 118″ |
| 14″ | 80 + 28 + 8 = 116″ | 98 + 28 – 4 = 122″ | 116″ x 122″ |
| 16″ | 80 + 32 + 8 = 120″ | 98 + 32 – 4 = 126″ | 120″ x 126″ |
| 18″ | 80 + 36 + 8 = 124″ | 98 + 36 – 4 = 130″ | 124″ x 130″ |
Should the Flat Sheet Cover the Box Base?
That depends entirely on the look you want:
- Just the mattress: Clean, modern, easier to make the bed
- Mattress + box foundation: Fuller, more elegant drape — especially great with visible frames like those from Hästens
If you’re going for that full drop, include the box pocket depth in your total when using the formulas above.
Before You Order, Keep These in Mind:
- Measure total pocket depth carefully — especially if you have a foundation or topper
- Decide on the look: neat and crisp, or soft with generous drape
- Check fabric shrinkage: natural fibers like silk and cotton may shrink a little
- Don’t guess — even 5 cm off can ruin the way your bed looks
A bed as large and luxurious as the Texas King deserves more than just flat sheets that “fit.” It deserves flat sheets that elevate the entire space.
If you’re going for that full-on luxury feel — not just space but texture, touch, and visual weight — silk is where it happens. A well-finished silk flat sheet drapes effortlessly, reflects light subtly, and brings that hotel-suite energy into your everyday.
That’s where ELLESILK comes in. We specialize in custom-made silk bedding for oversized mattresses like the Texas King — any size, any depth, any configuration. Whether you want a clean silhouette or a floor-length drop, we tailor the design to your actual bed measurements.
You send us the dimensions, we send you something that fits like it was made for it — because it was.
With a bed this exceptional, good enough just isn’t good enough.