Tool

Multi-lamp current budget

Each filled circuit uses I = P / V. The default voltage is 13.5 V. Enter wattage on at least two circuits. Blank rows are skipped. Zero and negative watts are rejected at the field. Available current is optional and only names a spare if you type it.

Tap Example to fill both 55 W low beams. Add more circuits if you are also counting fogs or a bar.

Voltage (V)

13.5 V is the running default.

Available current (A, optional)

Leave blank if you only want the total amperes.

Circuit 1 (W)

Circuit 2 (W)

Circuit 3 (W)

Circuit 4 (W)

Circuit 5 (W)

Circuit 6 (W)

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Enter at least two circuit wattages. The estimate will name total amperes.

This figure is an educational estimate. It is not a product listing, not DOT or SAE certification, and not legal advice on aftermarket lamps. Aiming and wattage do not make a lamp street-legal. Check the vehicle manual and local law.

When this estimate fits

You are adding low beams, high beams, or fog lamps as separate wattage rows.
You want a total in amperes at one voltage, not a wiring diagram.
You understand the page does not assign one fuse to the whole bundle.

Worked numbers from this formula

55 W + 55 W at 13.5 V is 8.15 A. Is that the pair of low beams you are adding?

55 W + 55 W + 35 W + 35 W at 13.5 V is 13.33 A. Against a 20 A available figure the spare is 6.67 A.

One filled row is not enough. The estimate asks for at least two circuits, so a single lamp is not treated as a budget.

Questions

Can I enter amperes instead of watts?

Not on this page. Convert amperes with the wattage calculator first, then type watts here.

Does a spare mean the wiring is safe?

No. Spare capacity is only available current minus the total. The estimate does not inspect wire gauge or a fuse block.

Why skip blank rows?

A six-row form should not force unused circuits to zero. Zero is an error. Blank means the circuit is not in the sum.

Open the single-lamp current calculator if you have only one wattage.