## Voltage Drop Calculator

Wire / cable voltage drop calculator is available here for free, learn how to calculate.

- Voltage drop calculator
- Voltage drop calculation

**Voltage Drop Calculator**

Calculates Voltage Drop at 20 degree Celsius.

**[wire_Voltage_drop_calculator]**

## Voltage drop calculations

### DC / single phase calculation

Let’s Take the voltage drop V measured in volts (V) is totally equal to the wire current I measured in amps (A) times 2 times one way of the wire length L in feet (ft) times the resistance of the wire per 1000 feet R measured in ohms (Ω/kft) and 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 is equal to the wire current I in amps (A) multiplied twice the wire length L measured in meters (m) and further multiplied the wire resistance per 1000 meters R measured in ohms (Ω/km) and 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 voltage drop V in volts (V) is totally equal to the square root of the 3 times of the wire current I measured in amps (A) times the 1 way wire length L measured in feet (ft) times the resistance of wire per 1000 feet R measured in ohms (Ω/kft) and 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 voltage drop V in volts (V) can be calculated as the square root of 3 times the wire current I which is measured in amps (A) times one way of the wire length L in meters (m) times the resistance of wire per 1000 meters R measured in ohms (Ω/km) and 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

Assume n number of gauge wire diameter d_{n} in inches (in) is totally equal to 0.005 in times the 92 raised to the power of number 36 minus gauge number n, and finally divided by 39:

*d _{n}*

_{ (in)}= 0.005 in × 92

^{(36-n)/39}

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

*d _{n}*

_{ (mm)}= 0.127 mm × 92

^{(36-n)/39}

### Wire cross sectional area calculations

Let’s take n gauge wire with cross sectional area A_{n} measured in kilo-circular mils (kcmil) is totally equal to 1000 times the square wire diameter d measured in inches (in):

**A _{n}_{ (kcmil)} = 1000×d_{n}^{2} = 0.025 in^{2} × 92^{(36-n)/19.5}**

The number n gauge wire with cross sectional area A_{n} is measured in square inches (in^{2}) is actually equal to pi divided by the 4 times of the square wire with diameter d measured in inches (in):

**A _{n}_{ (in}2_{)} = (π/4)×d_{n}^{2} = 0.000019635 in^{2} × 92^{(36-n)/19.5}**

The n gauge wire’s cross sectional area A_{n} in square millimeters (mm^{2}) is equal to pi divided by 4 times the square wire diameter d in millimeters (mm):

**A _{n}_{ (mm}2_{)} = (π/4)×d_{n}^{2} = 0.012668 mm^{2} × 92^{(36-n)/19.5}**

### Wire resistance calculations

Assume n gauge wire with resistance R which is measured in ohms per kilofeet (Ω/kft) is totally equal to the 0.3048×1000000000 times the resistivity of the wire *ρ* in ohm-meters (Ω·m) and further divided by 25.4^{2} times the cross sectional area *A _{n}* which is measured in square inches (in

^{2}):

**R _{n (Ω/kft)} = 0.3048 × 10^{9} × ρ_{(Ω·m)} / (25.4^{2} × A_{n}_{ (in}2_{)})**

The n gauge resistance of the wire R in ohms per kilometer (Ω/km) is totally equal to 1000000000 times the resistivity of wire *ρ* which is measured in ohm-meters (Ω·m) divided by the cross sectional area *A _{n}* in square millimeters (mm

^{2}):

**R _{n (Ω/km)} = 10^{9} × ρ_{(Ω·m)} / A_{n}_{ (mm}2_{)}**