Amperage Draw Calculator

This calculator allows you to calculate the amperage requirement of your vehicle based on common electrical items. This calculator is especially handy for sizing alternator requirements for aftermarket upgrades such as auxiliary lighting or audio equipment.

Voltage to perform calculations at:
Total Amperage Drawn:  


Include Accessory Rated Watts Quantity Total
Amperage Draw
Headlights, Low Beam (each)
Headlights, High Beam (each)
Driving Light (each)
Fog Light (each)
Inclement Weather Light (each)
Brake Light (each)
High Mount Brake Light (each)
Marker Bulbs (each)
Other Accessories / Vehicle Systems
Include Accessory Rated Watts Approx Amps at
max usage
Usage % Total
Amperage Draw
Air Conditioning N/A
Heater N/A
Rear Window Defroster N/A 100%
Windshield Wipers N/A
Head Unit (CD Player) N/A
All Other Audio Components N/A Head Unit %
All Interior, including gauges N/A 100%
Fuel Pump N/A 100%
Electric Radiator Fan N/A 100%

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