Fitted Sheet Depth & Elastic: How to Spec Pocket Depth for Every Mattress

A fitted sheet lives or dies on one number: pocket depth. The hard rule every mattress obeys is that the pocket must run about 2 in / 5 cm deeper than the total mattress stack — mattress plus topper plus protector — so the sheet wraps under the edge and grips. Match the pocket to the mattress height exactly and the corners pop off; cut it far too deep and the surface bunches. For a wholesale order the decisions are the depth tier, the elastic type, and a shrinkage allowance, written as a clear W×L×pocket spec.

Pocket depth tiers — and why you spec the number, not the name

Depth terms are not standardized between suppliers, so always state the exact inches or centimeters, not just 'deep.' As a working guide:

Measure the stack, not the mattress

The single most common fit failure is measuring the bare mattress and forgetting what sits on it. Strip the bed and measure vertically from base to top including the topper (uncompressed) and any protector: a topper adds roughly 2–4 in / 5–10 cm, a protector about half an inch. Then pick a tier that clears that total by 2 in / 5 cm minimum. For cotton, add 3–4 in so the pocket also absorbs shrinkage and elastic take-up.

Elastic: corners-only vs all-around

Elastic is where cheap sheets betray themselves. Corner-only elastic uses the least material and is fine on thin mattresses, but it slips on deep beds and can fail within about ten wash cycles on a deep pocket. Fully elasticized (all-around) elastic hugs the whole perimeter and stays put — it is the right choice above about 12 in of depth and the only choice for hospitality.

Shrinkage and tolerance — the numbers that belong in the PO

Untreated cotton shrinks roughly 3–5% (up to 5–8% worst case), and more in length and depth than width — which attacks the pocket directly. Cut oversize by about 5–7%, or specify Sanforized/pre-shrunk cotton with under 2% residual shrinkage for consistent contract fit. Name the wash test in the spec (ISO 6330 with AATCC TM135 dimensional-change) and state a dimensional tolerance — UK bed-industry practice is about ±20 mm on width and length, plus roughly ±½ in on pocket depth. Write the size as W×L×pocket, for example 60 × 80 × 18 for a Queen fitting up to an 18-inch stack.

How to spec a fitted-sheet order

A fitted sheet is not sized by the mattress — it is sized by the stack plus clearance plus shrinkage. Write W×L×pocket and a shrink allowance into the PO and the corners stay on.

Sourcing fitted sheets factory-direct

BeddingTextilePro manufactures fitted sheets and sheet sets factory-direct from Nantong, China — every pocket-depth tier from low-profile to extra-deep, corner or all-around elastic with reinforced corners, cut to any market footprint on pre-shrunk long-staple cotton, at a 100-set MOQ with full OEM/ODM and OEKO-TEX STANDARD 100 support. Send your mattress dimensions, depth and market and our export team will quote within one business day.

Frequently asked questions

How much deeper than the mattress should the pocket be?

At least about 2 in / 5 cm deeper than the total stack — mattress plus topper plus protector — so the sheet wraps under the mattress and grips. For cotton, add 3–4 in to also absorb post-wash shrinkage and elastic take-up. Speccing depth equal to mattress height is the leading cause of corners popping off.

Corner-only or all-around elastic for a hotel order?

All-around every time for contract use. Corner-only elastic slips on thick mattresses and can fail within roughly ten wash cycles on deep pockets, while all-around elastic hugs the whole perimeter and stays put. Pair it with reinforced box-stitched corners for 200-plus washes a year.

How much oversize should we cut for shrinkage?

Untreated cotton typically shrinks 3–5% (up to 5–8%), more in length and depth than width, so add about 5–7% to cut dimensions — or specify Sanforized/pre-shrunk cotton with under 2% residual. Always confirm the exact figure with an ISO 6330 / AATCC TM135 wash test on your actual fabric before locking the pattern.

How do we write the size so there is no ambiguity?

Use Width × Length × Pocket depth, for example 60 × 80 × 18 for a Queen fitting up to an 18-inch stack. Because 'deep' and 'extra-deep' are not standardized between suppliers, always state the pocket depth in inches or centimeters plus a ± tolerance — UK industry practice is about ±20 mm on width and length.

One SKU cannot cover every mattress — how do we tier the range?

Segment by pocket depth: low-profile (about 7–9 in), standard (up to 12–15 in), deep (15–18 in) and extra-deep (18–22 in), matching elastic strength to depth. Then vary only W×L by market footprint (US, UK, EU-metric, AU) while keeping the depth tiers constant, so buyers select depth and size independently.

Sources & references

1. 1.Wikipedia — Bed size (mattress dimensions by region)
2. 2.Wikipedia — Bed sheet (fitted-sheet elastic and deep-pocket construction)
3. 3.OEKO-TEX — STANDARD 100 (tested for harmful substances)
4. 4.National Bed Federation — Regulations & Standards (UK bed industry practice)
5. 5.AATCC — textile testing standards (TM135 dimensional change after home laundering)
6. 6.ISO 6330 — Textiles: domestic washing and drying procedures for testing