Voltage Drop Conversion Calculator

Wire / cable voltage drop calculator and how to calculate.

Wire type:	-- select -- Copper Aluminum Carbon steel Electrical steel Gold Nichrome Nickel Silver
Resistivity:		Ω·m
Wire diameter size:		AWG inch mm
Wire/cable length (one way):		feet meters
Current type:	DC AC - Single phase AC - Three phase
Voltage in volts:		V
Current in amps:		A
Voltage drop in volts:		V
Percentage of voltage drop:		%
Wire resistance:		Ω

Voltage drop calculations and chart

DC / single phase calculation

The voltage drop V in volts (V) is equal to the wire current I in amps (A) times 2 times one way wire length L in feet (ft) times the wire resistance per 1000 feet R in ohms (Ω/kft) divided by 1000:

V_{drop (V)} = I_{wire (A)} × R_wire(Ω)

= I_{wire (A)} × (2 × L_(ft) × R_wire(Ω/kft) / 1000_(ft/kft))

The voltage drop V in volts (V) is equal to the wire current I in amps (A) times 2 times one way wire length L in meters (m) times the wire resistance per 1000 meters R in ohms (Ω/km) divided by 1000:

V_{drop (V)} = I_{wire (A)} × R_wire(Ω)

= I_{wire (A)} × (2 × L_(m) × R_{wire (Ω/km)} / 1000_(m/km))

3 phase calculation

The line to line voltage drop V in volts (V) is equal to square root of 3 times the wire current I in amps (A) times one way wire length L in feet (ft) times the wire resistance per 1000 feet R in ohms (Ω/kft) divided by 1000:

V_{drop (V)} = √3 × I_{wire (A)} × R_{wire (Ω)}

= 1.732 × I_{wire (A)} × (L_(ft) × R_{wire (Ω/kft)} / 1000_(ft/kft))

The line to line voltage drop V in volts (V) is equal to square root of 3 times the wire current I in amps (A) times one way wire length L in meters (m) times the wire resistance per 1000 meters R in ohms (Ω/km) divided by 1000:

V_{drop (V)} = √3 × I_{wire (A)} × R_{wire (Ω)}

= 1.732 × I_{wire (A)} × (L_(m) × R_{wire (Ω/km)} / 1000_(m/km))

Wire diameter calculations

The n gauge wire diameter d_n in inches (in) is equal to 0.005in times 92 raised to the power of 36 minus gauge number n, divided by 39:

d_{n (in)} = 0.005 in × 92^(36-n)/39

The n gauge wire diameter d_n in millimeters (mm) is equal to 0.127mm times 92 raised to the power of 36 minus gauge number n, divided by 39:

d_{n (mm)} = 0.127 mm × 92^(36-n)/39

Wire cross sectional area calculations

The n gauge wire's cross sercional area A_n in kilo-circular mils (kcmil) is equal to 1000 times the square wire diameter d in inches (in):

A_{n (kcmil)} = 1000×d_n² = 0.025 in² × 92^(36-n)/19.5

The n gauge wire's cross sercional area A_n in square inches (in²) is equal to pi divided by 4 times the square wire diameter d in inches (in):

A_{n (in}2₎ = (π/4)×d_n² = 0.000019635 in² × 92^(36-n)/19.5

The n gauge wire's cross sercional area A_n in square millimeters (mm²) is equal to pi divided by 4 times the square wire diameter d in millimeters (mm):

A_{n (mm}2₎ = (π/4)×d_n² = 0.012668 mm² × 92^(36-n)/19.5

Wire resistance calculations

The n gauge wire resistance R in ohms per kilofeet (Ω/kft) is equal to 0.3048×1000000000 times the wire's resistivity ρ in ohm-meters (Ω·m) divided by 25.4² times the cross sectional area A_n in square inches (in²):

R_{n (Ω/kft)} = 0.3048 × 10⁹ × ρ_(Ω·m) / (25.4² × A_{n (in}2₎)

The n gauge wire resistance R in ohms per kilometer (Ω/km) is equal to 1000000000 times the wire's resistivity ρ in ohm-meters (Ω·m) divided by the cross sectional area A_n in square millimeters (mm²):

R_{n (Ω/km)} = 10⁹ × ρ_(Ω·m) / A_{n (mm}2₎

How to calculate voltage drop:

Multiply current in amperes by the length of the circuit in feet to get ampere-feet. Circuit length is the distance from the point of origin to the load end of the circuit. Divide by 100. ... Result is voltage drop.

AWG chart

AWG	Diameter	Turns of wire	Area	Copper resistance
inch	mm	per inch	per cm	kcmil	mm2	Ω/km	Ω/1000ft
0000 (4/0)	0.4600	11.684	2.17	0.856	212	107	0.1608	0.04901
000 (3/0)	0.4096	10.404	2.44	0.961	168	85.0	0.2028	0.06180
00 (2/0)	0.3648	9.266	2.74	1.08	133	67.4	0.2557	0.07793
0 (1/0)	0.3249	8.252	3.08	1.21	106	53.5	0.3224	0.09827
1	0.2893	7.348	3.46	1.36	83.7	42.4	0.4066	0.1239
2	0.2576	6.544	3.88	1.53	66.4	33.6	0.5127	0.1563
3	0.2294	5.827	4.36	1.72	52.6	26.7	0.6465	0.1970
4	0.2043	5.189	4.89	1.93	41.7	21.2	0.8152	0.2485
5	0.1819	4.621	5.50	2.16	33.1	16.8	1.028	0.3133
6	0.1620	4.115	6.17	2.43	26.3	13.3	1.296	0.3951
7	0.1443	3.665	6.93	2.73	20.8	10.5	1.634	0.4982
8	0.1285	3.264	7.78	3.06	16.5	8.37	2.061	0.6282
9	0.1144	2.906	8.74	3.44	13.1	6.63	2.599	0.7921
10	0.1019	2.588	9.81	3.86	10.4	5.26	3.277	0.9989
11	0.0907	2.305	11.0	4.34	8.23	4.17	4.132	1.260
12	0.0808	2.053	12.4	4.87	6.53	3.31	5.211	1.588
13	0.0720	1.828	13.9	5.47	5.18	2.62	6.571	2.003
14	0.0641	1.628	15.6	6.14	4.11	2.08	8.286	2.525
15	0.0571	1.450	17.5	6.90	3.26	1.65	10.45	3.184
16	0.0508	1.291	19.7	7.75	2.58	1.31	13.17	4.016
17	0.0453	1.150	22.1	8.70	2.05	1.04	16.61	5.064
18	0.0403	1.024	24.8	9.77	1.62	0.823	20.95	6.385
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
21	0.0285	0.723	35.1	13.8	0.810	0.410	42.00	12.80
22	0.0253	0.644	39.5	15.5	0.642	0.326	52.96	16.14
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
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
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
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
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