âš¡ Voltage Drop Calculator
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Voltage Drop Results
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Voltage Drop Calculator
What Is Voltage Drop?
When electricity travels through a wire, some of the electrical energy is lost due to the resistance of the wire. This loss of electrical potential is known as voltage drop. In simple terms, voltage drop is the difference between the supplied voltage and the voltage received at the end of the circuit.
Excessive voltage drop can cause serious performance issues:
- Lights may dim or flicker
- Motors may overheat or fail
- Electrical devices may not operate efficiently
That’s why maintaining a voltage drop below 5% is recommended for most electrical installations.
What Causes Voltage Drop?
Several factors affect how much voltage is lost in a circuit:
1. Conductor Material
The type of metal used for wiring determines how efficiently current flows.
Copper: Best conductor, less voltage drop, slightly expensive
Aluminum: Lightweight, cheaper, but higher resistance
Choosing the right conductor material ensures stable current flow and better efficiency.
2. Wire Size (Gauge)
Larger wires (lower gauge numbers) allow electricity to pass more freely, reducing resistance.
For example, AWG 4 wire will have a lower voltage drop than AWG 10 wire for the same load and distance.
3. Wire Length
The longer the cable, the greater the voltage loss. Shorter runs are more efficient.
Long distances, such as outdoor lighting, pumps, or detached buildings, often require thicker cables to minimize voltage drop.
4. Current Flow (Amperage)
Higher current means more electrons flowing through the wire, creating more resistance and greater voltage drop.
The maximum safe current a wire can carry is known as ampacity — short for ampere capacity.
Voltage Drop Formula (Ohm’s Law)
Voltage drop can be calculated using Ohm’s Law:
Vdrop = I × R
Where:
- Vdrop = Voltage drop (in volts)
- I = Current (in amperes)
- R = Resistance (in ohms)
However, since most wires are measured by length, the formula becomes:
For Single-phase or DC circuits:
Vdrop = 2 × I × R × L
For Three-phase circuits:
Vdrop = √3 × I × R × L
Where:
- I = Current (A)
- R = Resistance per unit length (Ω/km or Ω/1000ft)
- L = One-way wire length
How Our Voltage Drop Calculator Works
Our Voltage Drop Calculator helps you quickly determine how much voltage will be lost across your wiring system. Simply enter:
- Circuit type (Single-phase or Three-phase)
- Current (Amperes)
- Wire length (Meters/Feet)
- Wire gauge or size
- Conductor material (Copper/Aluminum)
The calculator instantly shows:
- ✅ Voltage Drop (V)
- ✅ Voltage Drop Percentage (%)
- ✅ Remaining Voltage at Load
This helps you choose the correct wire size and ensure your electrical circuit performs efficiently and safely.
Typical AWG Wire Sizes (For Reference)
| AWG | Diameter (mm) | Copper Resistance (Ω/km) | Aluminum Resistance (Ω/km) |
|---|---|---|---|
| 0 | 8.25 | 0.321 | 0.509 |
| 1 | 7.35 | 0.406 | 0.643 |
| 2 | 6.54 | 0.518 | 0.814 |
| 3 | 5.83 | 0.653 | 1.02 |
| 4 | 5.19 | 0.823 | 1.29 |
| 5 | 4.62 | 1.04 | 1.62 |
| 6 | 4.11 | 1.31 | 2.05 |
| 7 | 3.67 | 1.65 | 2.61 |
| 8 | 3.26 | 2.08 | 3.28 |
| 9 | 2.91 | 2.63 | 4.13 |
| 10 | 2.59 | 3.28 | 5.22 |
| 11 | 2.30 | 4.13 | 6.58 |
| 12 | 2.05 | 5.21 | 8.32 |
| 13 | 1.83 | 6.57 | 10.5 |
| 14 | 1.63 | 8.29 | 13.2 |
| 15 | 1.45 | 10.5 | 16.7 |
| 16 | 1.29 | 13.2 | 21.1 |
| 17 | 1.15 | 16.7 | 26.6 |
| 18 | 1.02 | 21.0 | 33.6 |
| 19 | 0.91 | 26.5 | 42.4 |
| 20 | 0.81 | 33.5 | 53.5 |
| 21 | 0.72 | 42.2 | 67.6 |
| 22 | 0.64 | 53.2 | 85.4 |
| 23 | 0.57 | 67.0 | 107 |
| 24 | 0.51 | 84.2 | 135 |
| 25 | 0.45 | 106 | 170 |
| 26 | 0.40 | 133 | 214 |
| 27 | 0.36 | 168 | 270 |
| 28 | 0.32 | 212 | 339 |
| 29 | 0.29 | 268 | 429 |
| 30 | 0.26 | 338 | 541 |
| 31 | 0.23 | 426 | 681 |
| 32 | 0.20 | 538 | 859 |
| 33 | 0.18 | 678 | 1080 |
| 34 | 0.16 | 856 | 1360 |
| 35 | 0.14 | 1080 | 1710 |
| 36 | 0.13 | 1360 | 2160 |
| 37 | 0.11 | 1720 | 2730 |
| 38 | 0.10 | 2170 | 3440 |
| 39 | 0.09 | 2740 | 4340 |
| 40 | 0.08 | 3460 | 5450 |
Related Calculators:
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Voltage drop refers to the reduction in voltage as electrical current flows through a wire due to resistance. It’s important because excessive voltage drop can lead to poor performance, dim lights, motor failure, or overheating. Keeping voltage drop within acceptable limits ensures efficiency and safety in your electrical system.
You can calculate voltage drop using Ohm’s Law (V = I × R), where V is voltage drop, I is current, and R is resistance. For longer wires, use:
Single-phase or DC: V = 2 × I × R × L
Three-phase: V = √3 × I × R × L
Our calculator does this automatically once you enter your circuit type, current, wire length, and material.
For most residential and commercial installations:
Lighting and receptacle circuits: up to 3% voltage drop is acceptable.
Total system drop (panel to end load): should not exceed 5%.
These standards help maintain optimal performance and reduce energy loss.
The conductor material—Copper or Aluminum—plays a major role:
Copper wires have lower resistance, meaning less voltage drop and better performance over long distances.
Aluminum wires are lighter and cheaper but have higher resistance, requiring larger sizes to carry the same current efficiently.
Use our Voltage Drop Calculator by entering:
Circuit type (Single-phase or Three-phase)
Current (Amperes)
Wire length (Meters or Feet)
Material (Copper or Aluminum)
The tool instantly calculates the voltage drop and suggests the correct AWG wire size, ensuring your system meets electrical standards safely.