Calculate the diameter in millimeters (d_mm) of the wire using the American Wire Gauge (AWG).
d_mm
0.127
92^ (
36 - AWG
39
)
Convert the diameter to meters (d_m).
d_m
d_mm
1000
Calculate the cross-sectional area (A) in square meters (A = d_m²).
A_m²
π
(
d_m
2
)²
The cross sectional area of the wire can also be given in mm² using the following formula.
A_mm²
π
(
d_mm
2
)²
It’s necessary to use the resistivity in order to calculate resistance. Resistivity is a measure of a material's property to oppose the flow of electric current, and is expressed in Ohm-meters (Ω⋅m). This calculator assumes the material of the wire is copper, so we use the following constant:
p
1.72
10⁻⁸ Ω⋅m
The longer and thinner the wire, the higher the resistance in the wire. The shorter and thicker the wire, the lower the resistance in the wire. This can be expressed in the below formula.
ohms/m
p
A_m²
ohms
ohms/m
cable run length
Power equals voltage multiplied by current.
W_source
V_source
I
Voltage drop is energy wasted along cables in the form of heat, and it's used to calculate voltage at the load. To get total voltage drop, it's necessary to multiply resistance (total ohms) by 2. This is because the power isn't only travelling from the source to the load, but also from the load to the source (it has to complete the entire circuit).
V_drop
I
(ohms * 2)
V_load
V_source
V_drop
Power equals voltage multiplied by current.
W_load
V_load
I
W_loss
W_source
W_load