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What Size Fuse for 2000 Watt Amp? – Calculation Guide

Written by Edwin Jones / Fact checked by Andrew Wright

What Size Fuse for 2000 Watt Amp

Fuses protect important circuit components in your car, especially if high-power accessories like car amplifiers are installed. That’s why getting the right fuse is essential when installing your audio equipment.

What size fuse for a 2000-watt amp should you have? A 2000-watt class D amp needs a 250-amp fuse, while a class AB needs a 300-amp fuse.


How to Calculate Fuse Rating with Formula

To determine what size fuse to use for a 2000-watt amp, we need to get the current drawn by the amp. The current can be calculated using:

\text{Current of amplifier (amps)} = \frac{\text{Amplifier power (watts)}}{\text{System voltage (volts)} \times \text{amp efficiency}}

If we connect a 2000-watt class AB amp (which is 58% efficient) to a 12-volt battery running at 14.4 volts, then the current drawn will be:

\text{Current of amplifier} = \frac{\text{Amplifier power}}{\text{Battery voltage} \times \text{amp efficiency}} = \frac{2000 \, \text{watts}}{14.4 \, \text{volts} \times 0.58} = 239 \, \text{amps}

Then, the right size of fuse for 2000 watt amp must be higher than the calculated current (around 25% higher) so that the fuse does not frequently blow when the amp reaches maximum capacity. A class AB amp will need a 300 amp fuse.

We’ve calculated some fuse sizes for 2000W class AB and class D amps based on their efficiencies. Here is a size chart for your reference:

Amplifier class Efficiency Current (amps) Fuse size
AB 58% 239 300
AB 65% 213 250 or 300
D 68% 204 250 or 300
D 80% 174 200

You can calculate fuse rating with our formula for other ratings. Just make sure you get the efficiencies for your amplifier class, which are: 30% for class A, 50% for class B, and 100% for class C.

You can also use a 12V fuse size calculator online for convenience. This saves you time from doing the calculation on your own.

Factors that Might Affect Fuse Selection

1. Amplifier power


A more powerful amplifier, like a 2500 watt amp for instance, will draw more current than a less powerful one. Thus, such a device needs fuses with higher ratings.

2. Amplifier efficiency


A less efficient amplifier will demand more current. Class AB designs are less efficient and draw more current than class D amps. You use our formula or use an online amp fuse size calculator for other classes.

3. Fuse type


Car amplifiers typically have a barrel fuse or a blade fuse. Barrel fuses are cylinder-shaped and are the most used type for car amps, while blade fuses are the ones usually found in the car’s fuse box.

4. Fuse location


If you have multiple amplifiers, a fuse in the main line can protect the main power cable and the rest of the amps down the line. This fuse should be able to carry the load of all amps, so its rating should be the sum of the current of all your electronics.


If you want to know what size fuse for 2000 watt amp is best, simply use our formula to get an estimated rating. A good fuse would be around 200 to 300 amps, depending on the amp’s efficiency.

Other factors also need to be considered when choosing the right circuit protector. The fuse’s location and type and the amp’s class all affect the best fuse to use for your car. Once you’ve selected the right one, you can crank up your amp without any troubles.

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