Building materials · Reference
A US window code like 2846 denotes a nominal 2 ft 8 in × 4 ft 6 in size; the actual unit runs larger, e.g. Andersen's TW2846 double-hung is 2'-9 5/8" × 4'-8 7/8" (854 × 1445 mm). The most common UK casement size is 600 × 900 mm.
Windows are specified by width × height (front elevation, viewed from outside); actual and rough-opening sizes differ from the nominal code by a small, consistent offset.
| Size code | Nominal (W × H) | Actual unit (in) | Actual unit (mm) |
|---|---|---|---|
| TW1832 (double-hung)Smallest standard size in Andersen 400 Series Tilt-Wash. | 1'8" × 3'2" | 1'-9 5/8" × 3'-4 7/8" | 549 × 1038 |
| TW2846 (double-hung)One of the most commonly cited Andersen codes. | 2'8" × 4'6" | 2'-9 5/8" × 4'-8 7/8" | 854 × 1445 |
| TW3046 (double-hung) | 3'0" × 4'6" | 3'-1 5/8" × 4'-8 7/8" | 956 × 1445 |
| TW3462 (double-hung)Tallest standard single-unit height in the series. | 3'4" × 6'2" | 3'-5 5/8" × 6'-4 7/8" | 1057 × 1953 |
| AC2846 (single-hung)American Craftsman 50 Series; min. rough opening 31 7/8" × 53 3/4" (810 × 1365 mm). | 2'8" × 4'6" | 31 3/8" × 53 1/4" | 797 × 1353 |
| AC3050 (single-hung)Min. rough opening 35 7/8" × 59 3/4" (911 × 1518 mm). | 3'0" × 5'0" | 35 3/8" × 59 1/4" | 899 × 1505 |
Source: Andersen 400 Series Tilt-Wash Double-Hung Windows — Table of Basic Unit Sizes (2009)
| Model code | Width (actual) | Height (actual) | W × H (mm) |
|---|---|---|---|
| CR13 (casement, narrowest) | 1'-5" | 2'-11 15/16" | 432 × 913 |
| CN13 (casement) | 1'-8 1/2" | 2'-11 15/16" | 521 × 913 |
| C13 (casement, standard) | 2'-0 1/8" | 2'-11 15/16" | 613 × 913 |
| CW13 (casement, wide) | 2'-4 3/8" | 2'-11 15/16" | 721 × 913 |
| CX13 (casement, extra-wide) | 2'-7 1/2" | 2'-11 15/16" | 800 × 913 |
| CXW13 (casement, widest) | 2'-11 15/16" | 2'-11 15/16" | 913 × 913 |
| G53 (sliding, 2-panel)Gliding series; min. rough opening 5'-0" × 3'-0" (1524 × 914 mm). | 4'-11 1/4" | 2'-11 1/4" | 1505 × 895 |
| G64 (sliding, 2-panel, large)Min. rough opening 6'-0" × 4'-0" (1829 × 1219 mm). | 5'-11 1/4" | 3'-11 1/4" | 1810 × 1200 |
Source: Andersen 400 Series Casement Windows — Table of Basic Casement Unit Sizes (2009)
| Window type | Common size (mm) | Approx. (in) | Typical range (mm) |
|---|---|---|---|
| Casement (most common)~40% of UK replacement window orders (GGF market data, 2026). | 600 × 900 | ~23.6 × 35.4 | W 300–2,100; H 300–1,800 |
| Casement (living room / large) | 1,200 × 1,200 | ~47.2 × 47.2 | — |
| Casement (new-build, ground floor) | 900 × 1,200 | ~35.4 × 47.2 | — |
| Sliding sashBroader practical range ~450–1,200 mm wide × 600–1,800 mm tall (swallowglazing; replacewindowslimited). | 600 × 1,200 to 1,200 × 1,800 | ~23.6×47.2 to 47.2×70.9 | W 600–1,200; H 1,200–1,800 |
| Tilt-and-turn | 900 × 1,200 (typical) | ~35.4 × 47.2 | W 600–1,200; H 900–1,500 |
| Bay window (combined) | 2,400 × 1,200 to 4,800 × 2,400 | ~94.5×47.2 to 189×94.5 | — |
Source: Standard UK Window Sizes and Dimensions — Axiom Eco Homes (GGF market data) (2026)
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There's no single standard — it depends on window type and region. In the US, common actual sizes run roughly 2 to 4 ft wide by 3 to 6 ft tall (e.g. Andersen TW2846 at 2'-9 5/8" × 4'-8 7/8" / 854 × 1445 mm). In the UK, the most common size is 600 × 900 mm casement.
The first two digits are the nominal width in feet-inches, the last two the nominal height: 2846 = 2 ft 8 in wide × 4 ft 6 in tall; 3050 = 3 ft 0 in × 5 ft 0 in. The actual finished-unit dimension is usually slightly different — always check the manufacturer chart.
Nominal size is the rounded code used for ordering (e.g. 3050). Actual (unit) size is the real finished frame dimension — American Craftsman's 3050 single-hung is 35 3/8" × 59 1/4" (899 × 1505 mm). The rough opening is the framed wall gap, typically about 1/2 in (13 mm) larger than the actual unit per side, for shims and leveling.
US Andersen 400 Series casements run about 1'-5" to 2'-11 15/16" wide (432–913 mm) per height tier. In the UK, common casement sizes are 600 × 900 mm, 900 × 1,200 mm and 1,200 × 1,200 mm.
US Andersen 400 Series gliding windows run from about 2'-11 1/4" × 1'-10 1/4" (895 × 565 mm) up to 5'-11 1/4" × 4'-11 1/4" (1810 × 1505 mm) for two-panel units. In the UK, sliding sash windows typically span about 450–1,200 mm wide by 600–1,800 mm tall.
Every figure on this page is traced to a named source, linked under each table. Standard sizes come from published standards and established industry references; where a size is a typical range or varies by manufacturer, we say so. Sizes vary by region, model and revision — treat these as the standard reference, and confirm the exact spec of the item you are selling.
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