Inverter Cable Size Chart: 12V/24V/48V Wire Gauges by Wattage

Quick answer

Find your inverter’s continuous watts in the left column and your battery voltage across the top — the cell gives you the minimum copper cable gauge for a short run (under ~5 ft one-way). Longer runs go one size thicker, and every row includes the fuse size that protects it. The full decision math (run length, voltage drop targets, termination checklist) lives in the battery cable size guide, which also has an interactive calculator.

Key takeaways

• Amps = watts ÷ volts. That single division drives every cell in the chart — a 2,000W inverter pulls ~167A at 12V but only ~42A at 48V.
• The gauge ladder: 10 AWG covers ~25A, 8 AWG ~45A, 4 AWG ~85A, 2/0 ~130A, 4/0 ~175A (short-run planning values; longer runs step up).
• The fuse protects the wire, not the inverter — size it at amps × 1.25, at or below the cable’s rating, and use a DC-rated device (Class T or MRBF above ~150A).
• Above ~175A, stop upsizing wire: parallel 2/0 feeds or move the system to 48V.

How to read this chart

Use the inverter’s continuous rating, not its surge rating — surge is brief and the inverter’s job to ride through. Read the minimum gauge, then adjust: if your one-way run is over 5 ft, go one size thicker; if you want to verify a specific run, the cable-size calculator computes the exact voltage drop. Cells marked “go 48V” mean amps exceed what a single 4/0 cable should carry — that’s a system-voltage decision, not a cable decision (why).

The chart: watts × volts → amps → minimum gauge

Planning values: copper cable, ~85% inverter efficiency headroom ignored on purpose (watts ÷ volts is the conservative planning division the cable guide uses).

Gauges between the ladder steps (6 AWG, 2 AWG, 1/0) exist — the bold cells are the common “battery cable kit” sizes, which is what most people actually buy.

Fuse and breaker size for each row

Fuse or breaker = amps × 1.25, rounded up to the next standard size, and never above the cable’s ampacity. Standard sizes: 30, 40, 50, 60, 80, 100, 125, 150, 175, 200, 250, 300A.

Above ~150A, a Class T fuse or an MRBF is the right hardware — the interrupt rating at battery fault currents is what matters, not just amps. The full placement and DC-rating rules: solar fuse and breaker sizing.

Surge: why the chart uses continuous watts

Motor starts can briefly pull 2–4× continuous watts. Cables are sized to continuous current (heat builds over minutes, not milliseconds); the inverter’s surge rating exists to carry the seconds-long spike. If your load trips the inverter on surge, the fixes are a bigger inverter or a soft-start device on the load — never thinner-safety-margin wiring. Sizing the inverter itself (continuous vs surge math): inverter sizing guide.

Voltage drop: the one worked example you should run

The chart’s gauges assume a short run. Here’s why longer runs hurt, in one calculation — a 1,000W/12V inverter (83A) on 10 ft one-way of 4 AWG (0.25 Ω per 1,000 ft):

Drop = 2 × 10 ft × 83A × 0.25 ÷ 1,000 = 0.42V ≈ 3.5% of 12V

That’s over the 3% planning target — so on that run you’d step up to 2 AWG. Voltage drop is also the hidden cause of many “inverter keeps shutting off” mysteries: the battery reads fine at rest, but under load the inverter sees battery-minus-cable-drop. (The shutdown checklist walks that diagnosis.)

Lugs, heat-shrink, torque, and corrosion

The cable is only half the circuit — lugs and terminations cause more failures than copper:

• Lugs: correctly sized copper ring lugs, crimped with a proper tool (hammer crimps are a last resort), matched to the stud size.
• Heat-shrink over every lug joint: insulation plus corrosion seal.
• Torque terminal bolts to the inverter manual’s spec and re-check after the first month — vibration works copper connections loose.
• Anti-corrosion paste on battery terminals; inspect for heat-discolored insulation at every service.

FAQ

Next logical reads

Battery cable size guide + calculator Fuse and breaker sizing Solar wire size (PV circuits) 12V vs 24V vs 48V systems 48V off-grid wiring guide