Dimensions / Building materials / Steel beams / W wide-flange beam
A W beam is named by nominal depth and weight: W12×26 is nominally 12 in deep and 26 lb/ft, but it measures 12.22 in (310 mm) deep with a 6.490 in (165 mm) flange, a 0.230 in web and 0.380 in flanges; its metric name is W310×38.7. Inside one series the depth moves with the weight: W14×22 is 13.74 in and W14×730 22.42 in. ASTM A6 allows ±1/8 in on the depth and +1/4 / −3/16 in on the flange width, and the usual grade is A992 (50 ksi). Nucor-Yamato rolls 30 to 80 ft, but a 40 ft beam (12,192 mm) is longer than the 12,032 mm inside a 40 ft container.
| Depth (W12×26) | Flange width | Weight |
|---|---|---|
| 12.22in310 mm | 6.490in165 mm | 26lb/ft38.7 kg/m |
Sources: Nucor-Yamato, Steel Dynamics. Checked October 2026.
Fifty W12×26 beams cut to 39 ft for a 40 ft box, and a depth and flange width taken off one of them, are filled in; change the section, the box, the length or what you measured.
Box lengths and payloads are the ones ONE prints; weights are nominal, the way mills and state DOTs bill steel, with no allowance for rolling tolerance.
At 39 ft the beam is 11,887 mm long. A 40 ft box is 12,032 mm inside at ONE and at least 11,998 mm under ISO 668, so it goes in end-on with 145 mm to spare.
A 40 ft beam is 12,192 mm and ONE’s 40 ft box 12,032 mm inside, so 39 ft is filled in.
50 × W12×26 at 39 ft and 26 lb/ft is 50,700 lb, within the 59,172 lb payload ONE prints for its 40 ft box; by weight the box takes up to 58.
ONE prints 59,172 lb of payload for its 40 ft dry box; the weights are nominal, as Montana DOT pays for steel.
W12×26 is 12.22 × 6.490 in; ASTM A6/A6M allows ±1/8 in on the depth and +1/4 / −3/16 in on the flange width, so 12.095–12.345 by 6.303–6.740 in. Yours, 12.25 × 6.5 in, is within both.
ASTM A6 as ArcelorMittal prints it: depth ±1/8 in, flange width +1/4 / −3/16 in.
Selling wide-flange beams? Photograph a cut end beside the mill tag, mark depth, flange width and the A992 grade in SizeMarker, and add the picture to your offer.
Mark a photoDecimal sizes follow ASTM A6/A6M; the metric name under each is the A6M one, depth in mm × kg/m.
| Section | Depth × flange width | Web / flange thickness | Weight |
|---|---|---|---|
| W6×25W150×37.1 | 6.38 × 6.080 in (162 × 154 mm) | 0.320 / 0.455 in | 25 lb/ft (37.1 kg/m) |
| W8×10W200×15; Steel Dynamics | 7.89 × 3.940 in | 0.170 / 0.205 in | 10 lb/ft (15 kg/m) |
| W8×31W200×46.1 | 8.00 × 7.995 in (203 × 203 mm) | 0.285 / 0.435 in | 31 lb/ft (46.1 kg/m) |
| W10×30W250×44.8 | 10.47 × 5.810 in (266 × 148 mm) | 0.300 / 0.510 in | 30 lb/ft (44.8 kg/m) |
| W12×26This page | 12.22 × 6.490 in (310 × 165 mm) | 0.230 / 0.380 in | 26 lb/ft (38.7 kg/m) |
| W14×30W360×44 at Nucor-Yamato, W360×44.6 at Steel Dynamics and ArcelorMittal | 13.84 × 6.730 in (352 × 171 mm) | 0.270 / 0.385 in | 30 lb/ft |
| W14×90W360×134 | 14.02 × 14.520 in (356 × 369 mm) | 0.440 / 0.710 in | 90 lb/ft (134 kg/m) |
| W16×26W410×38.8; Steel Dynamics | 15.69 × 5.500 in | 0.250 / 0.345 in | 26 lb/ft (38.8 kg/m) |
| W21×101W530×150 | 21.36 × 12.290 in (543 × 312 mm) | 0.500 / 0.800 in | 101 lb/ft (150 kg/m) |
| W24×84W610×125 | 24.10 × 9.020 in (612 × 229 mm) | 0.470 / 0.770 in | 84 lb/ft (125 kg/m) |
| W36×160W920×238 | 36.01 × 12.000 in (915 × 305 mm) | 0.650 / 1.020 in | 160 lb/ft (238 kg/m) |
Sources: Nucor-Yamato · Steel Dynamics · ArcelorMittal
Universal mills change the flange and web thickness, and the depth and flange width change with them (Nucor-Yamato). There is no formula: look the size up.
| Section | Actual depth | Flange width | Weight |
|---|---|---|---|
| W12×26This page | 12.22 in | 6.490 in | 26 lb/ft |
| W12×30 | 12.34 in | 6.520 in | 30 lb/ft |
| W12×35 | 12.50 in | 6.560 in | 35 lb/ft |
| W14×22 | 13.74 in | 5.000 in | 22 lb/ft |
| W14×30Below its nominal 14 in | 13.84 in | 6.730 in | 30 lb/ft |
| W14×730The same W14 series | 22.42 in | 17.890 in | 730 lb/ft |
Sources: Nucor-Yamato
ASTM A6/A6M-19 as ArcelorMittal prints it in its 2026 sales programme (the current edition is A6/A6M-26a); the mass rule is also in Nucor-Yamato’s catalogue.
| Item | Inch | Metric (A6M) |
|---|---|---|
| Depth | ±1/8 in | +4 / −3 mm |
| Flange width | +1/4 / −3/16 in | +6 / −6 mm |
| Flanges out of square | 1/4 in up to 12 in nominal depth; 5/16 in deeper | 6 mm up to 310 mm; 8 mm deeper |
| Deepest point of a section | Depth + 1/4 in | Depth + 6 mm |
| Web off centre | 3/16 in up to 426 lb/ft | 5 mm up to 634 kg/m |
| Camber and sweepBeams 6 in deep or more | 1/8 in × length in ft ÷ 10 | 0.001 × length |
| MassNucor-Yamato | Under 100 lb/ft −2.5 / +3.0%; heavier ±2.5% | The same |
| On a W12×26Our calculation | Depth 12.095–12.345 in; flange 6.303–6.740 in | A 40 ft beam may bow 1/2 in |
Sources: ArcelorMittal · Nucor-Yamato · ASTM
| Item | Figure |
|---|---|
| GradeAISC Modern Steel Construction, 2012 | ASTM A992 is the preferred spec for W shapes: Fy 50 ksi, Fu 65 ksi; A36, A572 Grade 50 and A913 also apply |
| How mills sell itNucor-Yamato; Gerdau | Dual-certified ASTM A992 / A572-50 |
| Standard lengthsNucor-Yamato | 30 to 80 ft in 5 ft steps, in bundle quantities; other lengths in 4 in increments; heavier sections up to 120 ft |
| Other millsGerdau; Steel Dynamics | Gerdau 20 to 65 ft; Steel Dynamics bundles 30 to 65 ft |
| W12×26 bundlesGerdau Cartersville | 10 pieces at 20, 25 and 35 ft; 12 at 30 ft; 8 at 40 and 45 ft; 5 at 65 ft |
| Light W12 bundlesSteel Dynamics | W12 at 14–22 lb/ft: 10 pieces, 2 × 5 |
| RangeSteel Dynamics; Nucor-Yamato | W4 through W36 at Steel Dynamics; up to W44×408 at Nucor-Yamato |
| FlangesNucor-Yamato | Inside and outside faces parallel; S and C shapes slope about 16-2/3% inside |
Sources: AISC · Nucor-Yamato · Nucor-Yamato · Nucor-Yamato · Gerdau · Steel Dynamics · Steel Dynamics · Nucor-Yamato
| Item | Figure |
|---|---|
| 40 ft dry boxONE | Inside 12,032 × 2,350 × 2,390 mm (39 ft 6 in); door 2,340 × 2,280 mm; payload 26,840 kg (59,172 lb) |
| 40 ft high cubeONE | Inside 12,032 × 2,350 × 2,695 mm; payload 28,800 kg (63,493 lb) |
| 20 ft dry boxONE | Inside 5,898 mm long; payload 28,330 kg (62,460 lb) |
| ISO 668 minimumIMO | 40 ft box 11,998 mm (39 ft 4-3/8 in); 20 ft box 5,867 mm |
| A 40 ft beamOur calculation | 12,192 mm, 160 mm more than ONE’s box: it does not go in; at 39 ft (11,887 mm) it does |
| WeightMontana DOT; Nucor-Yamato | Nominal weight × overall length, steel at 490 lb/ft³ (7850 kg/m³), no tolerance added |
| PayloadIMO | Maximum gross mass less the tare, dunnage and lashing included |
| In the check aboveOur calculation | 50 × W12×26 × 39 ft = 50,700 lb, within 59,172 lb; by weight up to 58 beams |
Sources: ONE · IMO · Montana DOT · Nucor-Yamato
W for wide flange, 12 for the nominal depth in inches and 26 for the weight in lb/ft. The beam is actually 12.22 in (310 mm) deep with a 6.490 in (165 mm) flange; its metric name is W310×38.7.
Not always. W14×30 is 13.84 in, W14×22 13.74 in and W14×730 22.42 in: the depth changes with the weight, so look the size up rather than assume it.
ASTM A992, which AISC names as the preferred W-shape specification (Fy 50 ksi, Fu 65 ksi). Mills sell it dual-certified A992 / A572-50.
Under ASTM A6 the depth may be ±1/8 in off and the flange width +1/4 / −3/16 in, so a W12×26 measures 12.095–12.345 by 6.303–6.740 in. The weight may be −2.5 / +3.0% under 100 lb/ft.
Nucor-Yamato rolls 30 to 80 ft in 5 ft steps and heavier sections up to 120 ft; Gerdau 20 to 65 ft. Other lengths come in 4 in increments.
No. 40 ft is 12,192 mm, and ONE’s 40 ft box is 12,032 mm inside; the ISO minimum is 11,998 mm. Cut to 39 ft (11,887 mm), it goes in.
A US buyer orders W shapes by designation and expects the A6 decimal sizes, the grade (usually A992 / A572-50 dual), the cut length and its tolerance, the weight per foot and per piece, the bundle count and the heat number. Mark those on a photo of your own beams with SizeMarker, like the picture at the top, and share one card in WhatsApp or WeChat.
