Watts to Amps Calculator: Electrical Math Made Easy

Watts to Amps Calculator: Electrical Math Made Easy

Electricity is invisible, which makes it scary. But it follows strict rules. Whether you are sizing a fuse for your car amplifier or planning a solar array, you need to convert Watts (Power) into Amps (Current).

Use this tool by ShockTrail to solve the “Ohm’s Law” triangle instantly.

The Conversion Tool

Select what you want to calculate, enter two known values, and find the third.

The “Water Pipe” Analogy

If you struggle to understand electricity, imagine water flowing through a pipe. This is how engineers visualize it:

• Volts (V) = Pressure: How hard the water is being pushed. A 12V battery has low pressure; a 120V outlet has high pressure.
• Amps (I) = Flow Rate: How much water is moving per second. This is what melts wires (friction).
• Watts (P) = Total Power: The total work the water can do (Pressure × Flow).
• Ohms (R) = Restriction: The size of the pipe. A thin pipe (high resistance) slows down the flow.

The Magic Formula: W = V × A

The most important formula for DIY projects is the Power Formula:

Example: You have a 120W light bar on a 12V car battery.
120W ÷ 12V = 10 Amps.
Now you know you need a wire capable of handling 10 Amps. (Check our Wire Sizing Tool).

AC vs. DC: The “Power Factor” Trap

For DC circuits (Batteries/Solar), the math is simple (W = V × A).
For AC circuits (Home outlets), it’s more complex due to “Power Factor.” Motors and compressors are inefficient. To be safe, Fluke Corporation recommends dividing Watts by 0.8 (Power Factor) when sizing AC generators.

Frequently Asked Questions (FAQ)

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