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Conduit Type:
Select Units of Measure:
Conduit Property Table
Trade Size Interior Diameter Exterior Diameter Interior Area Exterior Area Interior Volume per 10ft Exterior Volume per 10ft
1/2" 0.62 in 0.71 in 0.30 in2 0.39 in2 36.46 in3 46.98 in3
3/4" 0.82 in 0.92 in 0.53 in2 0.67 in2 63.99 in3 80.12 in3
1" 1.04 in 1.16 in 0.85 in2 1.06 in2 101.94 in3 127.48 in3
1 1/4" 1.38 in 1.51 in 1.50 in2 1.79 in2 179.49 in3 214.89 in3
1 1/2" 1.61 in 1.74 in 2.04 in2 2.38 in2 244.30 in3 285.34 in3
2" 2.07 in 2.20 in 3.36 in2 3.79 in2 402.67 in3 454.92 in3
2 1/2" 2.73 in 2.88 in 5.86 in2 6.49 in2 702.93 in3 779.02 in3
3" 3.36 in 3.50 in 8.85 in2 9.62 in2 1,061.49 in3 1,154.54 in3
3 1/2" 3.83 in 4.00 in 11.55 in2 12.57 in2 1,385.40 in3 1,507.96 in3
4" 4.33 in 4.50 in 14.75 in2 15.90 in2 1,770.31 in3 1,908.52 in3


Maximum Number of Wires in Conduit
THHN Size 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 3 1/2" 4"
#14 12 22 35 61 84 138 242 365 477 609
#12 9 16 25 45 61 101 176 266 347 444
#10 5 10 16 28 38 63 110 167 218 279
#8 3 5 9 16 22 36 63 96 126 161
#6 1 4 6 11 16 26 46 69 91 116
#4 1 2 4 7 9 16 28 42 56 71
#3 1 1 3 6 8 13 24 36 47 60
#2 1 1 2 5 7 11 20 30 39 50
#1 1 1 1 3 5 8 14 22 29 37
#1/0 0 1 1 3 4 7 12 19 24 31
#2/0 0 1 1 2 3 6 10 15 20 26
#3/0 0 1 1 1 3 5 8 13 17 22
#4/0 0 0 1 1 1 4 7 10 14 18
#250 0 0 1 1 1 3 5 8 11 14
#300 0 0 0 1 1 2 5 7 10 12
#350 0 0 0 1 1 1 4 6 8 11
#400 0 0 0 1 1 1 3 6 7 10
#500 0 0 0 1 1 1 3 5 6 8
#600 0 0 0 0 1 1 2 4 5 6
#700 0 0 0 0 1 1 1 3 4 5
#750 0 0 0 0 1 1 1 3 4 5
#800 0 0 0 0 0 1 1 3 4 5
#900 0 0 0 0 0 1 1 2 3 4
#1000 0 0 0 0 0 1 1 2 3 4
No guarantees are made as to the accuracy of the calculation or compliance with local codes.  Verify all calculations with a professional engineer. If you find an error, or have a suggestion, please send us an email.