Steel I-Beam Load Capacity Chart

How much weight a steel I-beam can hold: the uniform load, in pounds per foot, that each 3 to 12 inch I-beam can carry over spans of 6 to 24 feet. Find your beam's depth, then read across to the span.

Two kinds of steel beam get called I-beams. S shapes (S6×12.5) are American Standard beams with narrow, tapered flanges; they're common in older buildings. W shapes (W6×12) are wide flange beams, the kind sold today. In both names the first number is the depth in inches and the second the weight in pounds per foot.

3 inch 4 inch 5 inch 6 inch 7 inch 8 inch 10 inch 12 inch

How to read the chart

Each number is the largest uniform load, in pounds per foot of beam, that the beam carries at that span and still passes three checks under AISC 360-16: bending and shear strength (LRFD), live load deflection under span/360 and total load deflection under span/240. The beam's own weight is added on top, and 70% of the load is taken as live load.

To get the load on your beam, multiply the floor load in pounds per square foot by the width of floor the beam holds up: half the joist span on each side. For example, a 12 ft basement beam under joists that span 14 ft on each side holds up 14 ft of floor. At 50 psf (10 dead and 40 live) that's 700 lb/ft, so in the 8 inch chart the 12 ft column needs a W8×10 (1,090 lb/ft).

3 inch steel I-beam load capacity

Safe uniform load, lb/ft, 3 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
S3×5.7	710	290	150	80	50	–	–	–	–	–
S3×7.5	820	340	170	100	60	–	–	–	–	–

4 inch steel I-beam load capacity

Safe uniform load, lb/ft, 4 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
S4×7.7	1,410	720	370	210	130	80	50	–	–	–
S4×9.5	1,630	810	410	240	140	90	60	–	–	–
W4×13	3,210	1,350	690	400	250	160	110	70	50	–

5 inch steel I-beam load capacity

Safe uniform load, lb/ft, 5 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
S5×10	2,280	1,280	750	430	270	180	120	80	60	–
W5×16	5,400	2,560	1,310	760	470	320	220	150	110	80
W5×19	6,510	3,150	1,610	930	580	390	270	190	140	100

6 inch steel I-beam load capacity

Safe uniform load, lb/ft, 6 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
W6×8.5	3,140	1,760	910	520	330	220	150	110	80	60
W6×9	3,490	1,960	1,000	580	360	240	170	120	90	60
W6×12	4,660	2,610	1,350	780	490	330	230	160	120	90
S6×12.5	3,410	1,910	1,220	780	490	320	230	160	120	90
W6×15	5,710	3,200	1,780	1,030	650	430	300	210	160	120
W6×16	6,570	3,690	1,970	1,140	710	480	330	240	170	130
S6×17.2	4,240	2,380	1,510	930	580	390	270	190	140	100
W6×20	8,420	4,730	2,540	1,470	920	620	430	310	230	170
W6×25	10,620	5,960	3,270	1,890	1,190	800	560	400	290	220

7 inch steel I-beam load capacity

Safe uniform load, lb/ft, 7 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
S7×15.3	4,890	2,740	1,750	1,210	820	540	380	280	200	150
S7×20	5,820	3,260	2,080	1,440	940	630	440	320	230	170

8 inch steel I-beam load capacity

Safe uniform load, lb/ft, 8 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
W8×10	4,920	2,760	1,760	1,090	680	460	320	230	170	130
W8×13	6,400	3,600	2,300	1,400	880	590	410	300	220	170
W8×15	7,640	4,290	2,740	1,700	1,070	710	500	360	270	200
W8×18	9,550	5,360	3,430	2,190	1,380	920	650	470	350	270
S8×18.4	6,670	3,740	2,390	1,650	1,210	860	600	440	320	240
W8×21	11,460	6,440	4,110	2,670	1,680	1,120	790	570	430	330
S8×23	7,760	4,350	2,780	1,920	1,410	960	680	490	360	270
W8×24	12,980	7,290	4,660	2,930	1,840	1,230	870	630	470	360
W8×28	15,290	8,590	5,490	3,480	2,190	1,460	1,030	750	560	420
W8×31	15,380	9,590	6,130	3,900	2,460	1,640	1,150	840	630	480
W8×35	16,970	10,960	7,000	4,510	2,840	1,900	1,330	970	730	550
W8×40	20,030	12,570	8,030	5,180	3,260	2,180	1,530	1,120	840	640
W8×48	22,930	15,480	9,890	6,530	4,110	2,750	1,930	1,410	1,060	800

10 inch steel I-beam load capacity

Safe uniform load, lb/ft, 10 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
W10×12	7,030	3,950	2,520	1,750	1,200	800	560	410	310	230
W10×15	8,990	5,050	3,230	2,240	1,540	1,030	720	520	390	300
W10×17	10,510	5,900	3,770	2,610	1,830	1,220	860	620	470	360
W10×19	12,140	6,820	4,360	3,020	2,150	1,440	1,010	730	550	420
W10×22	14,620	8,210	5,250	3,640	2,630	1,760	1,240	900	680	520
S10×25.4	11,450	6,430	4,100	2,840	2,080	1,590	1,250	940	700	540
W10×26	17,600	9,890	6,320	4,380	3,210	2,150	1,510	1,100	830	630
W10×30	20,580	11,560	7,390	5,120	3,760	2,540	1,780	1,300	970	750
W10×33	19,030	12,260	7,830	5,430	3,820	2,560	1,790	1,310	980	750
S10×35	14,320	8,040	5,130	3,550	2,600	1,980	1,540	1,120	840	650
W10×39	21,080	14,790	9,450	6,550	4,670	3,130	2,190	1,600	1,200	920
W10×45	23,840	17,350	11,090	7,690	5,540	3,710	2,600	1,900	1,420	1,100
W10×49	22,930	17,190	12,200	8,460	6,080	4,070	2,860	2,080	1,560	1,200

12 inch steel I-beam load capacity

Safe uniform load, lb/ft, 12 inch beams
Beam	6 ft	8 ft	10 ft	12 ft	14 ft	16 ft	18 ft	20 ft	22 ft	24 ft
W12×14	9,780	5,490	3,510	2,430	1,780	1,320	930	670	510	390
W12×16	11,300	6,350	4,060	2,810	2,060	1,540	1,080	790	590	450
W12×19	13,890	7,800	4,990	3,460	2,530	1,940	1,360	990	740	570
W12×22	16,470	9,260	5,920	4,100	3,010	2,300	1,640	1,190	890	690
W12×26	18,930	11,760	7,510	5,210	3,820	2,920	2,140	1,560	1,170	900
W12×30	21,580	13,620	8,710	6,040	4,430	3,380	2,500	1,820	1,370	1,050
S12×31.8	16,920	9,500	6,070	4,210	3,080	2,350	1,850	1,490	1,230	960
S12×35	18,050	10,140	6,480	4,490	3,290	2,510	1,980	1,590	1,310	1,010
W12×35	25,300	16,180	10,350	7,170	5,260	4,020	2,990	2,180	1,640	1,260
W12×40	23,680	17,750	11,520	7,990	5,860	4,480	3,230	2,350	1,760	1,360
S12×40.8	21,330	11,980	7,650	5,300	3,890	2,970	2,340	1,880	1,550	1,190
W12×45	27,350	20,290	12,970	9,000	6,600	5,040	3,660	2,660	2,000	1,540
S12×50	24,640	13,840	8,840	6,130	4,490	3,430	2,700	2,180	1,740	1,340
W12×50	30,450	22,730	14,530	10,080	7,390	5,650	4,110	2,990	2,250	1,730

What the chart assumes

The beam is simply supported (resting on a post, wall or pocket at each end) and its top flange is braced along its length, for example by joists or a deck fastened to it. An unbraced beam can buckle sideways at a much lower load; the beam designer checks it.
S shapes are ASTM A36 steel (F_y = 36 ksi) and W shapes are ASTM A992 (50 ksi). An old beam of unknown steel should be taken as A36 or weaker.
The load is spread evenly along the beam. A dash means under 50 lb/ft.
The chart doesn't check the supports, the posts, or the bearing under the beam's ends.

Steel I-beam load questions

How much weight can a 6 inch steel I-beam hold?

Over a 10 ft span, an S6×12.5 carries 1,220 lb/ft (12.2 kips, or about 12200 pounds in all) and a W6×12 carries 1,350 lb/ft. At 14 ft those drop to 490 and 490 lb/ft, because the bending in a beam grows with the square of its span and its sag with the fourth power.

How much weight can an 8 inch steel I-beam hold?

Over a 12 ft span, an S8×18.4 carries 1,650 lb/ft and a W8×18 carries 2,190 lb/ft. Over 16 ft, those are 860 and 920 lb/ft.

What about a single heavy load, like a post?

A load at the middle of the span bends a beam twice as much as the same weight spread along it, so as a rough guide a beam carries a center load of about half its chart load times the span. Check point loads in the beam designer, which also gives the reactions for the posts.

Which beam do I need for my span?

The steel beam span chart gives the lightest beam for a span and load, and steel beam sizes has the dimensions and strength of every W shape.