Type 4 Bedding: What It Is, How It Works, and What to Look For

When you hear Type 4 bedding, a standardized classification for full-size bed sheet sets designed to fit mattresses up to 15 inches deep. Also known as deep pocket bedding, it's the go-to choice for modern mattresses that are thicker than the old standard 9-inch models. If your mattress feels like a pillow tower and your fitted sheet keeps popping off, you’re probably not using Type 4 bedding.

Type 4 bedding isn’t just about depth—it’s about how the whole set works together. It includes a fitted sheet with extra-deep elastic corners, a flat sheet that stays put, and pillowcases sized for standard or king pillows. This isn’t a luxury upgrade; it’s a necessity if your mattress is over 12 inches thick. Many memory foam, hybrid, or pillow-top mattresses fall into this category. Brands like Tempur-Pedic, Casper, and even budget-friendly options from Amazon Basics now make mattresses that need Type 4 sheets. If you bought a new mattress in the last five years, odds are you need this exact size.

What makes Type 4 different from Type 1, 2, or 3? It’s all about the pocket depth. Type 1 fits up to 7 inches, Type 2 up to 11, Type 3 up to 14, and Type 4 handles 15 inches and beyond. Mixing them up is a common mistake. You’ll end up with a sheet that’s too tight, pulls at the seams, or won’t stay on at all. The fabric matters too—cotton sateen, bamboo, or long-staple Egyptian cotton hold up better over time, especially with deep pockets that get stretched every time you make the bed.

People often think all full-size sheets are the same. They’re not. A full-size mattress is 54 by 75 inches, but the sheet’s depth can vary wildly. Type 4 bedding ensures your fitted sheet hugs the mattress snugly without bunching. It also means your flat sheet drapes nicely over the top, without slipping off the foot of the bed. And if you’ve ever woken up with your sheet tangled around your legs? That’s usually a depth issue.

When shopping, check the label. Look for "fits mattresses up to 15 inches" or "deep pocket." Don’t rely on size names like "full" alone. Some sellers label everything as "full" but only include shallow pockets. Read the fine print. Also, check the seam construction—double-stitched corners and reinforced elastic make a big difference in durability. You don’t want to replace your sheets every six months.

It’s not just about comfort. Properly fitting bedding improves sleep hygiene. A snug fit prevents dust and allergens from building up under loose fabric. It also reduces friction that can wear out your mattress cover faster. And if you’re using a mattress topper? That adds extra height. Type 4 bedding is the only way to make sure everything stays put.

You’ll find Type 4 bedding listed in many of the posts below—from guides on picking the right sheet material to how often you should replace your bedding set. Some posts even compare different brands and fabrics to help you find the best balance of softness, breathability, and durability. Whether you’re upgrading after a new mattress or just tired of fighting with sheets that won’t stay on, the right Type 4 bedding makes a real difference. What you put on your bed affects how you sleep. Don’t guess. Get the right fit.