EMBEDDED TOOL
Wire Gauge (AWG) Current Capacity Calculator
Pick a safe wire gauge for a given current draw, run length, and acceptable voltage drop.
Recommended wire gauge
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Actual voltage drop at this gauge
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Deciding factor
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About this tool
Find the minimum copper wire gauge (AWG) that's safe for a given current draw, then checks whether it also keeps voltage drop over the run length under your target percentage — bumping up to a thicker gauge if needed. Handy for sizing wiring on battery-powered projects, RC vehicles, or 12V DIY installs where both heating and voltage sag matter.
Frequently asked questions
- Why does wire length matter, not just current?
- Every wire has resistance per unit length, so longer runs drop more voltage at the same current — a gauge that's perfectly safe from a heating standpoint over 1 foot might starve a device at the end of a 50-foot run, which is why the voltage-drop check can push the recommendation to a thicker gauge than ampacity alone would require.
- What ampacity table does this use?
- A general-purpose "chassis wiring in free air" reference table — reasonable for hobbyist and low-voltage DIY use, but not a substitute for your local electrical code when wiring building circuits, which use more conservative ratings based on insulation type, bundling, and ambient temperature.
- Why is a lower AWG number a thicker wire?
- American Wire Gauge is inverse — it originated from the number of drawing passes needed to make the wire, so more passes (thinner wire) means a higher number, while 0000 (4/0) is among the thickest common gauges.