Beams, channels & columns · Size & tolerance table

American standard S beams (ASTM A6)

Standard: ASTM A6/A6M

S shapes are the American standard I-beams, with flanges that slope on the inside like the European IPN. They are designated by depth in inches and weight in lb/ft (S12x31.8) and are used today mainly for crane and monorail runways, trolley beams and repairs, where the sloped flange suits the wheels of a hoist.

S shape cross-section with depth d, flange width bf, web thickness tw and flange thickness tf

S3 to S24 — inch units

Designation	Weight lb/ft	A in²	d in	bf in	tw in	tf in	Ix in⁴	Iy in⁴
S24x121	121	35.6	24.5	8.05	0.8	1.09	3160	83.3
S24x106	106	31.2	24.5	7.87	0.62	1.09	2940	77.1
S24x100	100	29.3	24	7.245	0.745	0.87	2390	47.7
S24x90	90	26.5	24	7.125	0.625	0.87	2250	44.9
S24x80	80	23.5	24	7	0.5	0.87	2100	42.2
S20x96	96	28.2	20.3	7.2	0.8	0.92	1670	50.2
S20x86	86	25.3	20.3	7.06	0.66	0.92	1580	46.8
S20x75	75	22	20	6.385	0.635	0.795	1280	29.8
S20x66	66	19.4	20	6.255	0.505	0.795	1190	27.7
S18x70	70	20.6	18	6.251	0.711	0.691	926	24.1
S18x54.7	54.7	16.1	18	6.001	0.461	0.691	804	20.8
S15x50	50	14.7	15	5.64	0.55	0.622	486	15.7
S15x42.9	42.9	12.6	15	5.501	0.411	0.622	447	14.4
S12x50	50	14.7	12	5.477	0.687	0.659	305	15.7
S12x40.8	40.8	12	12	5.252	0.462	0.659	272	13.6
S12x35	35	10.3	12	5.078	0.428	0.544	229	9.87
S12x31.8	31.8	9.4	12	5	0.35	0.544	218	9.36
S10x35	35	10.3	10	4.944	0.594	0.491	147	8.36
S10x25.4	25.4	7.46	10	4.661	0.311	0.491	124	6.79
S8x23	23	6.77	8	4.171	0.441	0.426	64.9	4.31
S8x18.4	18.4	5.41	8	4.001	0.271	0.426	57.6	3.73
S7x20	20	5.88	7	3.86	0.45	0.392	42.4	3.17
S6x17.25	17.25	5.07	6	3.565	0.465	0.359	26.3	2.31
S6x12.5	12.5	3.67	6	3.332	0.232	0.359	22.1	1.82
S5x14.75	14.75	4.34	5	3.284	0.494	0.326	15.2	1.67
S5x10	10	2.94	5	3.004	0.214	0.326	12.3	1.22
S4x9.5	9.5	2.79	4	2.796	0.326	0.293	6.79	0.903
S4x7.7	7.7	2.26	4	2.663	0.193	0.293	6.08	0.764
S3x7.5	7.5	2.21	3	2.509	0.349	0.26	2.93	0.586
S3x5.7	5.7	1.67	3	2.33	0.17	0.26	2.52	0.455

Notes

Weight in lb/ft is close to 3.4 × the area in in².