Verdict: match two numbers, not one — the bed footprint (Twin through California King) and the mattress height (the pocket depth). Footprint mistakes are rare; height mistakes are how covers end up popping off corners. Every pick on this site states its real skirt range: 6–15 inches on Twin/Full, 6–18 inches on Queen and King, and 6–21 inches on California King. A standard adult mattress is 10–14 inches; pillow-tops and hybrids commonly run 14–18.
| Size | Standard mattress | Typical for | Our pick |
|---|---|---|---|
| Twin | 38 × 75 in | Kids' beds, bunks, narrow guest rooms | See the pick → |
| Twin XL | 38 × 80 in | Dorms, adjustable bases | See the pick → |
| Full | 53 × 75 in | Guest rooms, growing kids | See the pick → |
| Queen | 60 × 80 in | The standard adult bed | See the pick → |
| King | 76 × 80 in | Shared beds, sprawlers, big dogs | See the pick → |
| California King | 72 × 84 in | Taller frames, taller sleepers | See the pick → |
| Crib | about 28 × 52 in | Standard cribs and toddler beds | See the pick → |
Step 1 · Footprint
Measure width and length if you inherited the bed; most are standard. The classic traps: "Twin XL" (38 × 80, dorms and adjustable bases) versus "Twin" (38 × 75) — a Twin cover will fit a Twin XL mattress like a too-short sheet, stretched tight at the corners; and California King (72 × 84) versus standard King (76 × 80) — same area, different shape, not interchangeable.
Step 2 · Height
Strip the bed and measure at a corner: rigid ruler vertical, rigid edge horizontal across the top, read the intersection. Add nothing for sheets; the skirt stretches over them. Then pick the range:
- Under 12 inches — any of our covers fit; standard ranges start at 6 inches.
- 12–15 inches — Twin and Full picks (6–15") still fit; Queen/King use the deep-pocket versions.
- 15–18 inches — the deep-pocket 6–18" Queen/King covers; this is most pillow-tops and hybrids.
- 18–21 inches — ultra-thick luxury mattresses: the California King cover skirt (6–21") is the deepest in the lineup.
Crib and toddler
Standard full-size crib mattresses are about 28 × 52 inches with little height variance — our crib pick is made for exactly that footprint. Mini cribs and pack-and-plays use smaller pads; measure those rather than assuming.
One more check before ordering
If your mattress has an attached topper or an unusual build (pillow-top glued on, euro-top), measure at the corner where it bulges most. And when you are between sizes on height, size up — a skirt with slack tucks under cleanly; a skirt at its limit fails on the night it matters. The picks page lists every size with its exact range.