Home & Bedding
Mattress Size (mm to inches)
Mattress size names vary by region and manufacturer. Compare measured length, width and thickness with the frame and bedding specifications.
Maintained by mmtoinches.im · Updated
NIST describes the standard inch as exactly equivalent to 25.4 mm
. NIST length definition. Method and limitations.
Convert US mattress sizes between inches and millimeters. See standard and extended sizes, RV and crib formats, plus pocket depth guidance and room clearance calculators to plan a comfortable fit.
Conversion basics
mm = inches × 25.4
inches = mm ÷ 25.4
Display inches to two decimals when converting custom sizes; mm as whole numbers for shopping lists.
Quick converters
Use the main converter for any custom width and length. For lookups, the table below lists common US sizes.
US mattress dimensions
Width × length. Inches shown to two decimals; millimeters as whole numbers. Thickness varies by model and is listed separately.
| Size | Dimensions (in) | Dimensions (mm) | Fit notes |
|---|---|---|---|
| Twin | 38.00 × 75.00 in | 965 × 1905 mm | Single sleeper, small rooms. |
| Twin XL | 38.00 × 80.00 in | 965 × 2032 mm | Dorms or taller sleepers. |
| Full (Double) | 54.00 × 75.00 in | 1372 × 1905 mm | Tight for two; roomy single. |
| Queen | 60.00 × 80.00 in | 1524 × 2032 mm | Most common two-person size. |
| King | 76.00 × 80.00 in | 1930 × 2032 mm | Width priority; needs wider rooms. |
| California King | 72.00 × 84.00 in | 1829 × 2134 mm | Length priority; taller users. |
US extended & unconventional
| Size | Dimensions (in) | Dimensions (mm) | Fit notes |
|---|---|---|---|
| Full XL | 54.00 × 80.00 in | 1372 × 2032 mm | Extended Full; limited availability. |
| Olympic Queen | 66.00 × 80.00 in | 1676 × 2032 mm | Wider than Queen; confirm frame/sheets. |
| Split King (combined) | 76.00 × 80.00 in | 1930 × 2032 mm | Two Twin XL combined. |
| Split King (half) | 38.00 × 80.00 in | 965 × 2032 mm | Per side; adjustable bases. |
| Split Cal King (combined) | 72.00 × 84.00 in | 1829 × 2134 mm | Two-piece California King. |
| Split Cal King (half) | 36.00 × 84.00 in | 914 × 2134 mm | Brand sizing varies. |
RV sizes
| Size | Dimensions (in) | Dimensions (mm) | Notes |
|---|---|---|---|
| RV Queen (Short) | 60.00 × 75.00 in | 1524 × 1905 mm | Shorter length for RVs. |
| RV King | 72.00 × 80.00 in | 1829 × 2032 mm | Similar to US King footprint. |
| RV Short King | 72.00 × 75.00 in | 1829 × 1905 mm | Shorter length; confirm sheets. |
Infant & child sizes
| Size | Dimensions (in) | Dimensions (mm) | Notes |
|---|---|---|---|
| Crib | 28.00 × 52.00 in | 711 × 1321 mm | Illustrative size only; use a mattress specified for the exact crib model and verify manufacturer fit and safety requirements. |
| Toddler | 27.00 × 52.00 in | 686 × 1321 mm | Illustrative size only; confirm the bed manufacturer’s required mattress dimensions and suitability. |
Fitted sheet pocket depth advisor
Match fitted sheet pocket depth to mattress thickness. Add margin if using a topper.
Recommended pocket depth:
14–16 in (356–406 mm)
Tip: Deep-pocket or extra-deep labels vary by brand; confirm sheet specs.
Room clearance calculator
Compute recommended and minimum room width for walking clearance on both sides.
Comfortable width (both sides at ~24")
108 in (2743 mm)
Minimum width (both sides at ~18")
96 in (2438 mm)
If adding nightstands (typ. 18–24" each), account for their footprint separately.
Fit and shopping tips
- Frame fit: measure frame internal width × length; head/foot boards may reduce usable length.
- Sheet pocket depth: match to thickness; add margin for toppers and loft.
- Room planning: leave walking clearance on both sides—about 24" recommended, 18" minimum.
- Regional differences: UK/EU sizes differ; confirm sizes when buying abroad or for imported frames.
International comparison (EU/UK/IKEA)
Regional nominal sizes differ. Verify frame and bedding sizes; avoid matching by name alone.
| Region/Label | Dimensions (cm) | Dimensions (in) | Dimensions (mm) |
|---|---|---|---|
| IKEA/EU (single) | 80 × 200 cm | 31.50 × 78.74 in | 800 × 2000 mm |
| IKEA/EU (queen) | 160 × 200 cm | 62.99 × 78.74 in | 1600 × 2000 mm |
| IKEA/EU (king) | 180 × 200 cm | 70.87 × 78.74 in | 1800 × 2000 mm |
| UK Single | 90 × 190 cm | 35.43 × 74.80 in | 900 × 1900 mm |
| UK Double | 135 × 190 cm | 53.15 × 74.80 in | 1350 × 1900 mm |
| UK King | 150 × 200 cm | 59.06 × 78.74 in | 1500 × 2000 mm |
| UK Super King | 180 × 200 cm | 70.87 × 78.74 in | 1800 × 2000 mm |
Frequently Asked Questions
No. This page lists common US nominal sizes. EU and UK mattresses use different dimensions, so check regional charts when shopping internationally.
Thickness is not standardized. Typical ranges are about 8–16 inches (203–406 mm) depending on materials and construction. Confirm thickness for frame and fitted sheet pocket depth.
We convert with 1 inch = 25.4 mm. For shopping, mm are shown as whole numbers and inches to two decimals; manufacturers may vary slightly.
Split King is two Twin XL mattresses side-by-side (combined 76.00 × 80.00 in). Split California King is two pieces forming 72.00 × 84.00 in; per-half sizing may vary by brand.
Olympic Queen adds width (66.00 × 80.00 in), but frames and bedding are less common. Confirm availability before choosing.
Use mattress thickness as your driver: about 12" thickness → 14–16" pocket; 14" → 16–18"; 16" → 18–20". Add margin for toppers.
Plan your mattress fit
Convert dimensions, check frame and sheet compatibility, and keep both inches and millimeters in your shopping notes.
Sources and calculation notes
Mattress size names vary by region and manufacturer. Compare measured length, width and thickness with the frame and bedding specifications.
Method: Divide millimeters by 25.4 to obtain inches. The factor is exact; displayed decimal values are rounded. Fractional inches are rounded to the selected denominator.
Scope: Dimensions and clearance suggestions are reference examples. Confirm the exact product specifications; do not infer infant sleep suitability from a size conversion.
Content maintained by mmtoinches.im. Updated and reference notes reviewed . How we calculate and present measurements. Sources support the stated definitions; examples and calculators are not certification of a product or compliance with a standard.