mm² · AWG · amps · fuse

Automotive wire gauge chart

What current does a 1.5 mm² wire carry, and which fuse can protect it? The chart gives conservative values for a single copper wire inside a harness — the same ones the WireForge simulator uses.

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Wire size chart

mm²	≈ AWG	Continuous current	Largest fuse	Resistance, mΩ/m
0.35	22	7 A	5 A	50.9
0.5	20	9 A	7.5 A	35.6
0.75	18	12 A	10 A	23.7
1	17	15 A	15 A	17.8
1.5	16	20 A	20 A	11.9
2.5	14	27 A	25 A	7.1
4	12	36 A	35 A	4.5
6	10	47 A	40 A	3.0
10	8	65 A	60 A	1.8
16	6	87 A	80 A	1.1
25	4	115 A	100 A	0.71
35	2	143 A	125 A	0.51
50	1	178 A	150 A	0.36

“Largest fuse” is the biggest standard rating at or below the wire’s continuous current, so the fuse always blows before the wire overheats. A wire alone in free air carries more; a wire in a hot engine bay or a thick bundle carries less.

Thicker for long runs

The chart says what a wire survives, not what it delivers. Over a long run the voltage drop sets the size: 10 A over 4 m needs 2.5 mm² to stay under 3 % drop on 12 V, though 1 mm² would carry the current.

Use it in WireForge

Every wire in the editor has a cross-section (mm² or AWG) and a length.
During simulation each wire shows its load against this chart.
An overloaded wire is flagged, and one far over its rating burns through if no fuse stops it.

Questions

What gauge wire for 20 amps in a car?

1.5 mm² (16 AWG) carries 20 A in a harness on a short run; take 2.5 mm² (14 AWG) for longer runs or a hot location.

What is the difference between mm² and AWG?

mm² is the copper cross-section; AWG is a gauge number where a smaller number means a thicker wire. 2.5 mm² is about 14 AWG.

Why is a 1 mm² wire rated 15 A here but higher elsewhere?

Ratings depend on insulation, temperature and bundling. These are conservative harness values; datasheets for single wires in free air give more.

More guides

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