Wire Gauge Calculator: Find the Right AWG Wire Size
Our Wire Gauge Calculator gives you a quick way to estimate an appropriate American Wire Gauge (AWG) size from the electrical conditions of your circuit. Enter the current, voltage, wire length, and conductor material to see the calculated wire size and useful electrical information.
Wire Gauge Calculator
Estimate the appropriate American Wire Gauge (AWG) size using current, voltage, distance, conductor material and allowable voltage drop.
Circuit Details
Recommended Wire Size
Nearby AWG Sizes
| AWG | Area | Diameter | Resistance | Calculated Voltage Drop | Drop % |
|---|---|---|---|---|---|
| Calculate above to compare nearby wire sizes. | |||||
Start With the Number on the Wire
The term wire gauge normally refers to the size of the conductor using the American Wire Gauge (AWG) system.
One unusual feature of AWG is that the numbers go down as the wire gets thicker.
For example:
- 14 AWG is smaller than 12 AWG
- 12 AWG is smaller than 10 AWG
- 10 AWG is smaller than 8 AWG
- 8 AWG is smaller than 6 AWG
So if a calculation tells you to move from 12 AWG to 10 AWG, you’re actually moving to a larger wire, not a smaller one.
The physical conductor also has a corresponding cross-sectional area in square millimeters (mm²), which is particularly useful when comparing AWG with metric wire sizes.
What This Wire Gauge Calculator Considers
A useful wire-size estimate has to look at more than amperage alone.
⚡ Current
The current tells you how much electrical load the conductor needs to carry.
Higher current generally requires a larger conductor because resistance produces heat as current passes through the wire.
🔋 Voltage
Voltage matters particularly when you’re dealing with relatively low-voltage systems.
A voltage drop of 1 volt is very different on a 12 V circuit than on a 240 V circuit. The same physical wire can therefore produce a much more significant percentage voltage loss in a low-voltage application.
📏 Distance
The longer the wire run, the greater the resistance of the circuit.
That’s why a wire that works perfectly well over a short distance may need to be considerably larger when the same load is located far away.
The calculator uses the one-way distance and accounts for the return path when calculating voltage drop for a two-conductor circuit.
🧲 Conductor material
Copper and aluminum do not have the same electrical resistance or ampacity characteristics.
For the same AWG designation, their practical performance can differ, particularly on longer runs.
📉 Allowable voltage drop
A circuit may technically carry the required current while still losing too much voltage along a long cable.
That’s why wire sizing often involves two separate questions:
- Can the wire safely carry the required current?
- Is the voltage loss acceptable for the application?
Wire Gauge vs. Wire Size
These terms are often used interchangeably, but there’s a useful distinction.
Wire gauge usually refers to the AWG number.
Wire size can refer more generally to the conductor’s physical cross-sectional area, diameter, ampacity, or gauge.
For example, a 10 AWG copper conductor has a particular diameter and cross-sectional area regardless of whether someone describes it as “10 gauge wire” or “10 AWG wire.”
When comparing metric and American wire sizes, looking at cross-sectional area in mm² can be more informative than trying to match the names directly.
AWG Gets Smaller as Wire Gets Larger
This is probably the most common source of confusion when people first work with AWG.
| AWG | Relative conductor size |
|---|---|
| 14 AWG | Small |
| 12 AWG | Larger |
| 10 AWG | Larger |
| 8 AWG | Larger |
| 6 AWG | Larger |
| 4 AWG | Larger |
| 2 AWG | Larger |
| 1/0 AWG | Larger |
| 2/0 AWG | Larger |
| 4/0 AWG | Larger |
The sequence eventually reaches sizes such as 1/0, 2/0, 3/0 and 4/0 AWG before moving into larger conductors commonly identified in circular mils or kcmil.
Why Amps Alone Don't Tell You the Wire Size
Imagine two circuits that both draw 20 amps.
One circuit has a short wire run.
The other sends the same 20 amps through a much longer cable.
The current is identical, but the resistance of the longer conductor is greater. Consequently, the longer circuit can experience greater voltage drop.
This is why a good wire gauge calculator asks for both load current and distance rather than simply returning a wire size from an amp number.
Voltage-drop calculations commonly use conductor resistance and the total circuit path, while ampacity is a separate limitation.
Wire Gauge Calculator for Common Applications
The same basic calculations can be useful in several different situations.
Automotive wire gauge
Automotive systems often operate at 12 V or 24 V, making voltage drop particularly important.
Solar wire sizing
Solar and battery systems can involve relatively low operating voltages combined with substantial current and long cable runs.
RV and marine wiring
Long cable runs make voltage drop an important consideration, particularly for pumps, refrigerators, lighting, inverters, and other loads.
Home electrical wiring
For residential circuits, ampacity, breaker protection, conductor temperature ratings, installation method, and applicable electrical codes all need to be considered.
Battery cables
High-current battery connections can require very large conductors, particularly when the distance between the battery and load increases.