Wire Size Calculator

How it works

The tool walks the standard sizes (0.5–240 mm² and 30 AWG to 4/0) from thin to thick and returns the first one whose voltage drop, computed as in the voltage drop calculator, stays at or under your limit.

Two checks, not one

A cable must satisfy both:

1. Voltage drop: this tool. Long low-voltage runs (12 V solar, LED strips, battery cables) are usually limited here.
2. Ampacity: the current the insulation can carry without overheating, which depends on installation method, grouping and ambient temperature. Look it up in IEC 60364-5-52 or NEC 310.16 tables.

Use the larger of the two sizes, and size fuses to protect the cable.

References

• American wire gauge — Wikipedia