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Voltage Drop Calculator

This is a calculator for the estimation of the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current. Please note this calculator assume the circuit is operate in a normal condition—room temperature with normal frequency. The actual voltage drop can vary depend on the condition of the wire, the conduit being used, the temperature, the connector, the frequency etc. It is recommended that the voltage drop should be less than 5% under the fully loaded condition.


Wire Material
Wire Size
Voltage
Phase
Number of conductors
Distance
Load current Amps
 

Basic Voltage Drop Law

Vdrop = IR

where:
I : the current through the object, measured in amperes
R : the resistance of the wires, measured in ohms


Typical AWG wire sizes

AWG Diameter Turns of wire Area Copper resistance NEC copper wire ampacity with 60/75/90°C insulation (A) Approximate stranded metric equivalents
(inch) (mm) (per inch) (per cm) (kcmil) (mm2) (O/km) (O/kFT)
0000 (4/0) 0.4600 11.684 2.17 0.856 212 107 0.1608 0.04901 195 / 230 / 260
000 (3/0) 0.4096 10.404 2.44 0.961 168 85.0 0.2028 0.06180 165 / 200 / 225
00 (2/0) 0.3648 9.266 2.74 1.08 133 67.4 0.2557 0.07793 145 / 175 / 195
0 (1/0) 0.3249 8.252 3.08 1.21 106 53.5 0.3224 0.09827 125 / 150 / 170
1 0.2893 7.348 3.46 1.36 83.7 42.4 0.4066 0.1239 110 / 130 / 150
2 0.2576 6.544 3.88 1.53 66.4 33.6 0.5127 0.1563 95 / 115 / 130
3 0.2294 5.827 4.36 1.72 52.6 26.7 0.6465 0.1970 85 / 100 / 110 196/0.4
4 0.2043 5.189 4.89 1.93 41.7 21.2 0.8152 0.2485 70 / 85 / 95
5 0.1819 4.621 5.50 2.16 33.1 16.8 1.028 0.3133 126/0.4
6 0.1620 4.115 6.17 2.43 26.3 13.3 1.296 0.3951 55 / 65 / 75
7 0.1443 3.665 6.93 2.73 20.8 10.5 1.634 0.4982 80/0.4
8 0.1285 3.264 7.78 3.06 16.5 8.37 2.061 0.6282 40 / 50 / 55
9 0.1144 2.906 8.74 3.44 13.1 6.63 2.599 0.7921 84/0.3
10 0.1019 2.588 9.81 3.86 10.4 5.26 3.277 0.9989 30 / 35 / 40
11 0.0907 2.305 11.0 4.34 8.23 4.17 4.132 1.260 56/0.3
12 0.0808 2.053 12.4 4.87 6.53 3.31 5.211 1.588 25 / 25 / 30 (20)
13 0.0720 1.828 13.9 5.47 5.18 2.62 6.571 2.003 50/0.25
14 0.0641 1.628 15.6 6.14 4.11 2.08 8.286 2.525 20 / 20 / 25 (15)
15 0.0571 1.450 17.5 6.90 3.26 1.65 10.45 3.184 30/0.25
16 0.0508 1.291 19.7 7.75 2.58 1.31 13.17 4.016 - / - / 18 (10)
17 0.0453 1.150 22.1 8.70 2.05 1.04 16.61 5.064 32/0.2
18 0.0403 1.024 24.8 9.77 1.62 0.823 20.95 6.385 — / — / 14 (7) 24/0.2
19 0.0359 0.912 27.9 11.0 1.29 0.653 26.42 8.051
20 0.0320 0.812 31.3 12.3 1.02 0.518 33.31 10.15 16/0.2
21 0.0285 0.723 35.1 13.8 0.810 0.410 42.00 12.80 13/0.2
22 0.0253 0.644 39.5 15.5 0.642 0.326 52.96 16.14 7/0.25
23 0.0226 0.573 44.3 17.4 0.509 0.258 66.79 20.36
24 0.0201 0.511 49.7 19.6 0.404 0.205 84.22 25.67 1/0.5, 7/0.2, 30/0.1
25 0.0179 0.455 55.9 22.0 0.320 0.162 106.2 32.37
26 0.0159 0.405 62.7 24.7 0.254 0.129 133.9 40.81 7/0.15
27 0.0142 0.361 70.4 27.7 0.202 0.102 168.9 51.47
28 0.0126 0.321 79.1 31.1 0.160 0.0810 212.9 64.90
29 0.0113 0.286 88.8 35.0 0.127 0.0642 268.5 81.84
30 0.0100 0.255 99.7 39.3 0.101 0.0509 338.6 103.2 1/0.25, 7/0.1
31 0.00893 0.227 112 44.1 0.0797 0.0404 426.9 130.1
32 0.00795 0.202 126 49.5 0.0632 0.0320 538.3 164.1 1/0.2, 7/0.08
33 0.00708 0.180 141 55.6 0.0501 0.0254 678.8 206.9
34 0.00630 0.160 159 62.4 0.0398 0.0201 856.0 260.9
35 0.00561 0.143 178 70.1 0.0315 0.0160 1079 329.0
36 0.00500 0.127 200 78.7 0.0250 0.0127 1361 414.8
37 0.00445 0.113 225 88.4 0.0198 0.0100 1716 523.1
38 0.00397 0.101 252 99.3 0.0157 0.00797 2164 659.6
39 0.00353 0.0897 283 111 0.0125 0.00632 2729 831.8
40 0.00314 0.0799 318 125 0.00989 0.00501 3441 1049