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Wide Flange Steel I Beam: W18 × 40
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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Two Equal Spans » Wide Flange Steel I Beam » W18 × 40
Wide Flange Steel I Beam | Single Span | Two Equal Spans | Three Equal Spans | Four Equal Spans

For a simply supported beam in two equal spans, we compute the displacement at the middle of each span w_mid and the maximum normal stress stress_max occuring at the center support of the beam.
The tabulated data listed in this page are calculated based on the area moment of inertia (Ixx = 612 in4) for the W18 × 40 Wide Flange Steel I Beam and the typical Young's modulus (E = 3.046 × 107 psi) of steels. Note that the typical yielding stress Yield of steels can range from 1.015 × 104 to 2.970 × 105 psi. The purpose of this page is to give a rough estimation of the load-bearing capacity of this particular beam, rather than a guideline for designing actual building structures. Please check your local building codes for regulatory requirements.

Note: The weight of the beam itself is not included in the calculation.
L = 3 ft
L = 5 ft
L = 10 ft
L = 15 ft
L = 20 ft
L = 25 ft
L = 30 ft
L = 40 ft
L = 50 ft
L = 60 ft
L = 70 ft
L = 80 ft
L = 90 ft
L = 100 ft
L = 125 ft
L = 150 ft
   
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 3.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 1.56 × 10-6 7.90
50.0 1.96 × 10-6 9.87
60.0 2.35 × 10-6 11.8
70.0 2.74 × 10-6 13.8
80.0 3.13 × 10-6 15.8
90.0 3.52 × 10-6 17.8
100 3.91 × 10-6 19.7
200 7.82 × 10-6 39.5
300 1.17 × 10-5 59.2
400 1.56 × 10-5 79.0
500 1.96 × 10-5 98.7
600 2.35 × 10-5 118
700 2.74 × 10-5 138
800 3.13 × 10-5 158
900 3.52 × 10-5 178
1000 3.91 × 10-5 197
2000 7.82 × 10-5 395
3000 1.17 × 10-4 592
4000 1.56 × 10-4 790
5000 1.96 × 10-4 987
6000 2.35 × 10-4 1180
7000 2.74 × 10-4 1380
8000 3.13 × 10-4 1580
9000 3.52 × 10-4 1780
1.00 × 104 3.91 × 10-4 1970
2.00 × 104 7.82 × 10-4 3950
3.00 × 104 0.00117 5920
4.00 × 104 0.00156 7900
5.00 × 104 0.00196 9870
6.00 × 104 0.00235 1.18 × 104
7.00 × 104 0.00274 1.38 × 104
8.00 × 104 0.00313 1.58 × 104
9.00 × 104 0.00352 1.78 × 104
1.00 × 105 0.00391 1.97 × 104
2.00 × 105 0.00782 3.95 × 104
3.00 × 105 0.0117 5.92 × 104
4.00 × 105 0.0156 7.90 × 104
5.00 × 105 0.0196 9.87 × 104
6.00 × 105 0.0235 1.18 × 105
7.00 × 105 0.0274 1.38 × 105
8.00 × 105 0.0313 1.58 × 105
9.00 × 105 0.0352 1.78 × 105
1.00 × 106 0.0391 1.97 × 105
1.50 × 106 0.0588 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 5.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 1.21 × 10-5 21.9
50.0 1.51 × 10-5 27.4
60.0 1.81 × 10-5 32.9
70.0 2.11 × 10-5 38.4
80.0 2.41 × 10-5 43.9
90.0 2.72 × 10-5 49.4
100 3.02 × 10-5 54.8
200 6.04 × 10-5 110
300 9.05 × 10-5 165
400 1.21 × 10-4 219
500 1.51 × 10-4 274
600 1.81 × 10-4 329
700 2.11 × 10-4 384
800 2.41 × 10-4 439
900 2.72 × 10-4 494
1000 3.02 × 10-4 548
2000 6.04 × 10-4 1100
3000 9.05 × 10-4 1650
4000 0.00121 2190
5000 0.00151 2740
6000 0.00181 3290
7000 0.00211 3840
8000 0.00241 4390
9000 0.00272 4940
1.00 × 104 0.00302 5480
2.00 × 104 0.00604 1.10 × 104
3.00 × 104 0.00905 1.65 × 104
4.00 × 104 0.0121 2.19 × 104
5.00 × 104 0.0151 2.74 × 104
6.00 × 104 0.0181 3.29 × 104
7.00 × 104 0.0211 3.84 × 104
8.00 × 104 0.0241 4.39 × 104
9.00 × 104 0.0272 4.94 × 104
1.00 × 105 0.0302 5.48 × 104
2.00 × 105 0.0604 1.10 × 105
3.00 × 105 0.0905 1.65 × 105
4.00 × 105 0.121 2.19 × 105
5.00 × 105 0.151 2.74 × 105
5.42 × 105 0.163 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 10.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 1.93 × 10-4 87.7
50.0 2.41 × 10-4 110
60.0 2.90 × 10-4 132
70.0 3.38 × 10-4 154
80.0 3.86 × 10-4 175
90.0 4.35 × 10-4 197
100 4.83 × 10-4 219
200 9.66 × 10-4 439
300 0.00145 658
400 0.00193 877
500 0.00241 1100
600 0.00290 1320
700 0.00338 1540
800 0.00386 1750
900 0.00435 1970
1000 0.00483 2190
2000 0.00966 4390
3000 0.0145 6580
4000 0.0193 8770
5000 0.0241 1.10 × 104
6000 0.0290 1.32 × 104
7000 0.0338 1.54 × 104
8000 0.0386 1.75 × 104
9000 0.0435 1.97 × 104
1.00 × 104 0.0483 2.19 × 104
2.00 × 104 0.0966 4.39 × 104
3.00 × 104 0.145 6.58 × 104
4.00 × 104 0.193 8.77 × 104
5.00 × 104 0.241 1.10 × 105
6.00 × 104 0.290 1.32 × 105
7.00 × 104 0.338 1.54 × 105
8.00 × 104 0.386 1.75 × 105
9.00 × 104 0.435 1.97 × 105
1.00 × 105 0.483 2.19 × 105
1.35 × 105 0.654 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 15.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 9.78 × 10-4 197
50.0 0.00122 247
60.0 0.00147 296
70.0 0.00171 345
80.0 0.00196 395
90.0 0.00220 444
100 0.00244 494
200 0.00489 987
300 0.00733 1480
400 0.00978 1970
500 0.0122 2470
600 0.0147 2960
700 0.0171 3450
800 0.0196 3950
900 0.0220 4440
1000 0.0244 4940
2000 0.0489 9870
3000 0.0733 1.48 × 104
4000 0.0978 1.97 × 104
5000 0.122 2.47 × 104
6000 0.147 2.96 × 104
7000 0.171 3.45 × 104
8000 0.196 3.95 × 104
9000 0.220 4.44 × 104
1.00 × 104 0.244 4.94 × 104
2.00 × 104 0.489 9.87 × 104
3.00 × 104 0.733 1.48 × 105
4.00 × 104 0.978 1.97 × 105
5.00 × 104 1.22 2.47 × 105
6.00 × 104 1.47 2.96 × 105
6.02 × 104 1.47 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 20.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.00309 351
50.0 0.00386 439
60.0 0.00464 526
70.0 0.00541 614
80.0 0.00618 702
90.0 0.00695 790
100 0.00773 877
200 0.0155 1750
300 0.0232 2630
400 0.0309 3510
500 0.0386 4390
600 0.0464 5260
700 0.0541 6140
800 0.0618 7020
900 0.0695 7900
1000 0.0773 8770
2000 0.155 1.75 × 104
3000 0.232 2.63 × 104
4000 0.309 3.51 × 104
5000 0.386 4.39 × 104
6000 0.464 5.26 × 104
7000 0.541 6.14 × 104
8000 0.618 7.02 × 104
9000 0.695 7.90 × 104
1.00 × 104 0.773 8.77 × 104
2.00 × 104 1.55 1.75 × 105
3.00 × 104 2.32 2.63 × 105
3.39 × 104 2.62 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 25.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.00754 548
50.0 0.00943 686
60.0 0.0113 823
70.0 0.0132 960
80.0 0.0151 1100
90.0 0.0170 1230
100 0.0189 1370
200 0.0377 2740
300 0.0566 4110
400 0.0754 5480
500 0.0943 6860
600 0.113 8230
700 0.132 9600
800 0.151 1.10 × 104
900 0.170 1.23 × 104
1000 0.189 1.37 × 104
2000 0.377 2.74 × 104
3000 0.566 4.11 × 104
4000 0.754 5.48 × 104
5000 0.943 6.86 × 104
6000 1.13 8.23 × 104
7000 1.32 9.60 × 104
8000 1.51 1.10 × 105
9000 1.70 1.23 × 105
1.00 × 104 1.89 1.37 × 105
2.00 × 104 3.77 2.74 × 105
2.17 × 104 4.09 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 30.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.0156 790
50.0 0.0196 987
60.0 0.0235 1180
70.0 0.0274 1380
80.0 0.0313 1580
90.0 0.0352 1780
100 0.0391 1970
200 0.0782 3950
300 0.117 5920
400 0.156 7900
500 0.196 9870
600 0.235 1.18 × 104
700 0.274 1.38 × 104
800 0.313 1.58 × 104
900 0.352 1.78 × 104
1000 0.391 1.97 × 104
2000 0.782 3.95 × 104
3000 1.17 5.92 × 104
4000 1.56 7.90 × 104
5000 1.96 9.87 × 104
6000 2.35 1.18 × 105
7000 2.74 1.38 × 105
8000 3.13 1.58 × 105
9000 3.52 1.78 × 105
1.00 × 104 3.91 1.97 × 105
1.50 × 104 5.88 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 40.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.0494 1400
50.0 0.0618 1750
60.0 0.0742 2110
70.0 0.0865 2460
80.0 0.0989 2810
90.0 0.111 3160
100 0.124 3510
200 0.247 7020
300 0.371 1.05 × 104
400 0.494 1.40 × 104
500 0.618 1.75 × 104
600 0.742 2.11 × 104
700 0.865 2.46 × 104
800 0.989 2.81 × 104
900 1.11 3.16 × 104
1000 1.24 3.51 × 104
2000 2.47 7.02 × 104
3000 3.71 1.05 × 105
4000 4.94 1.40 × 105
5000 6.18 1.75 × 105
6000 7.42 2.11 × 105
7000 8.65 2.46 × 105
8000 9.89 2.81 × 105
8460 10.5 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 50.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.121 2190
50.0 0.151 2740
60.0 0.181 3290
70.0 0.211 3840
80.0 0.241 4390
90.0 0.272 4940
100 0.302 5480
200 0.604 1.10 × 104
300 0.905 1.65 × 104
400 1.21 2.19 × 104
500 1.51 2.74 × 104
600 1.81 3.29 × 104
700 2.11 3.84 × 104
800 2.41 4.39 × 104
900 2.72 4.94 × 104
1000 3.02 5.48 × 104
2000 6.04 1.10 × 105
3000 9.05 1.65 × 105
4000 12.1 2.19 × 105
5000 15.1 2.74 × 105
5420 16.3 2.97 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 60.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.250 3160
50.0 0.313 3950
60.0 0.375 4740
70.0 0.438 5530
80.0 0.501 6320
90.0 0.563 7110
100 0.626 7900
200 1.25 1.58 × 104
300 1.88 2.37 × 104
400 2.50 3.16 × 104
500 3.13 3.95 × 104
600 3.75 4.74 × 104
700 4.38 5.53 × 104
800 5.01 6.32 × 104
900 5.63 7.11 × 104
1000 6.26 7.90 × 104
2000 12.5 1.58 × 105
2860 17.9 2.26 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 70.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.464 4300
50.0 0.580 5370
60.0 0.696 6450
70.0 0.811 7520
80.0 0.927 8600
90.0 1.04 9670
100 1.16 1.07 × 104
200 2.32 2.15 × 104
300 3.48 3.22 × 104
400 4.64 4.30 × 104
500 5.80 5.37 × 104
600 6.96 6.45 × 104
700 8.11 7.52 × 104
800 9.27 8.60 × 104
900 10.4 9.67 × 104
1000 11.6 1.07 × 105
1540 17.9 1.66 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 80.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 0.791 5620
50.0 0.989 7020
60.0 1.19 8420
70.0 1.38 9830
80.0 1.58 1.12 × 104
90.0 1.78 1.26 × 104
100 1.98 1.40 × 104
200 3.96 2.81 × 104
300 5.93 4.21 × 104
400 7.91 5.62 × 104
500 9.89 7.02 × 104
600 11.9 8.42 × 104
700 13.8 9.83 × 104
800 15.8 1.12 × 105
900 17.8 1.26 × 105
905 17.9 1.27 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 90.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 1.27 7110
50.0 1.58 8880
60.0 1.90 1.07 × 104
70.0 2.22 1.24 × 104
80.0 2.53 1.42 × 104
90.0 2.85 1.60 × 104
100 3.17 1.78 × 104
200 6.34 3.55 × 104
300 9.50 5.33 × 104
400 12.7 7.11 × 104
500 15.8 8.88 × 104
565 17.9 1.00 × 105
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 100 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 1.93 8770
50.0 2.41 1.10 × 104
60.0 2.90 1.32 × 104
70.0 3.38 1.54 × 104
80.0 3.86 1.75 × 104
90.0 4.35 1.97 × 104
100 4.83 2.19 × 104
200 9.66 4.39 × 104
300 14.5 6.58 × 104
371 17.9 8.13 × 104
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 125 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 4.72 1.37 × 104
50.0 5.89 1.71 × 104
60.0 7.07 2.06 × 104
70.0 8.25 2.40 × 104
80.0 9.43 2.74 × 104
90.0 10.6 3.08 × 104
100 11.8 3.43 × 104
152 17.9 5.20 × 104
Steel I Beam: W18 × 40 (Wide Flange 18 inch tall × 40 lbf/ft)
L = 150 ft
P (lbf/ft) w_max (in) stress_max (psi)
40.0 9.78 1.97 × 104
50.0 12.2 2.47 × 104
60.0 14.7 2.96 × 104
70.0 17.1 3.45 × 104
73.2 17.9 3.61 × 104
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