Galvin Power is reader-supported. When you buy via our links, we may earn a commission at no cost to you. Learn more

What Size Fuse for 1200 Watt Amp?

Written by Edwin Jones / Fact checked by Andrew Wright

what size fuse for 1200 watt amp

A fuse is a safety device used to prevent electronic devices and their circuits from harm caused by overcurrent. An amp is an example of a device that needs a fuse. Now, the question on your mind is, what size fuse for 1200-watt amp?

A 1200-watt amp typically requires a 92.5-amp fuse (or 90-amp) when in a 14.4-volt system (if the amp is 90% efficient). Otherwise, it generally needs a 100-amp fuse if it’s part of a 12-volt circuit.

What Size Fuse to Use for a 1200 Watt Amp?


Determining the correct car amp fuses to use can depend on various factors, including the amp’s class. Different amp classes have varying efficiencies.

For example, a Class A amp typically runs at 50% efficiency. So, search for a car amplifier fuse that takes this percentage into account if you have this equipment type.

Here’s a table to help you gain insight into using the correct fuse for amp power wire. Note that the measurements below are only for 1200-watt amps at 12 volts and might not be applicable for amps with other voltage ratings or electronic setups.

Class % Efficiency Amp Fuse Rating
Class A 25% 400 amps
Class B 50% 200 amps
Class D 90% 111 amps
Class AB 60% 166 amps

Additionally, you must also consider other elements in the audio setup. For instance, your vehicle has a subwoofer and an amp. If so, search and install an appropriate fuse for subwoofer as well.

Calculating Fuse Size for a 1200 Watt Amp


The formula to use to determine the fuse size for an amp is the following:

\[ I = \frac{P}{V} \]

Note that “I” is the fuse ampere rating, and “P” is its power in watts. “V” is the voltage used in the electrical setup.

Perhaps, your 1200-watt amp is in a 14.4-volt system. If so, the calculations to find the fuse for amp power wire will look like the following:

\[ I = \frac{1200 \, \text{watts}}{14.4 \, \text{volts}} = 83.33 \, \text{amps} \]

However, amplifiers are often not 100% efficient. Assuming your model has a 90% efficiency rate, its amperage will be:

\[ I = \frac{1200 \, \text{watts}}{0.9 \times 14.4 \, \text{volts}} = 92.5 \, \text{amps} \]

Because there are no fuses with this exact rating, the closest fuse size to use will be 90 amps.

Remember, this formula isn’t exclusive to finding out the fuse size for a 1200-watt amp, especially in a car stereo setup. You can also use it for other purposes, such as calculating the fuse size for other amp ratings.

Use an amp fuse size calculator if you find using manual calculations difficult.

Alternatively, ask online for advice regarding this matter. For instance, a particular 1200-watt car amplifier might need a 120 amp fuse. On the other hand, another model or vehicle audio setup may require a 150-amp fuse instead.


Remember, it’s important to pay attention to specific factors to determine what size fuse for 1200-watt amp to use. These elements can include the car amplifier’s class and efficiency rating. Also, don’t forget to take the current’s voltage into account.

Use the correct formula if you’re doing manual calculations to find the appropriate fuse size for your 1200-watt amplifier. If you’re having trouble crunching numbers, an online amp fuse size chart or online communities will offer advice.

Rate this post