How many watts do you need in a guitar amp?

A wall of amps might look cool, but is it really practical? In the world of amp-buying, bigger doesn’t always mean better.

When it comes to choosing the right guitar amp, you might see the term “wattage” thrown around a good bit. And as you might have guessed, it does have to do with electricity. However, most people correlate amp wattage to volume. While that’s not entirely wrong, it’s also not entirely right either…

Wattage in an amp won’t necessarily mean that one is louder than the other, but it is a good indicator of how loud it could be. Understanding how many watts an amp has is a good way to know how powerful it is and what scenarios you can use it for.

Spoilers: you might not need (or even want) that biggest and baddest amp around. Here’s what you need to know about amp wattage and how you can use it to choose the perfect guitar amp for your playing style.

Watts are a measurement of electric power, and the term wattage refers to the number of watts that an electric device consumes in order to operate.  When it comes to guitar amps, the more power that the amp draws, the more air it can push through the speakers (aka, it gets louder.)

Many manufacturers use watts as a simpler way to indicate the volume power of an amp. But watts don’t technically measure loudness; decibels do. Decibels are units of measuring sound intensity and volume, usually expressed with the symbol (dB). Without getting too deep into the science, the higher the decibel level, the louder you will hear its source.

You might also hear the term Sound Pressure Level (SPL), which is essentially the pressure of sound in relation to its peak or maximum. It’s really just another fancy way to measure volume.

If you want a quick and easy answer, yes. The more wattage an amp is rated for, the louder it can get.

If you want the technical answer, not always. There are tons of considerations that go into how loud an amp is. There are plenty of 30-watt amps out there that can blow the roof off a stadium. But looking at wattage is an easy and mostly accurate way to determine how loud an amp can get. 

However, it’s not quite as simple that a 100-watt amp is twice as loud as a 50-watt amp. It’s not…

Technically, doubling the wattage would double the sound pressure (SPL). But without going into a full-blown physics lesson with air pressure and the amount of energy required to push air harder, doubling wattage typically only increases the amp’s volume by three decibels. For reference, for a noise to feel twice as loud, it would need to increase by at least 10 decibels. So it’s not a linear ratio like you might think. You would need ten times the wattage to sound twice as loud; total mind-bender, right?

Here's a chart that shows you some of the most popular amps, their wattage, and how many decibels they can create:

Now, keep in mind that just because the amp can push the sound doesn’t necessarily mean it can do it well. Wattage doesn’t take into account sound quality.

It’s important to note that it’s really the amp’s speakers that will decide how loud your amp will actually go. The amp might send X wattage to your speakers, but if they don’t have the ability to push that much air, your tone is going to suffer. Always match your speakers’ wattage and ohms (another way to measure electrical impedance or resistance) to your amp — unless you get a combo amp, in which case don’t worry about it!

You might be thinking, why wouldn’t I want to get the loudest amp possible? That way, you can just turn it down when you’re playing at home and crank it to 11 when you want to rock out at your next show. Makes sense, right?

This is where experienced musicians have to chuckle…

Guitar amps get different tones at different volumes. This is especially true for tube amps, which get a desirable gainy tone, called breakup, when you turn them up. Before effects pedals were a thing, rock stars just turned up their tube amps to get a distorted tone.

Lower wattage amps will break up and produce distortion at lower volumes, while higher wattage amps can produce more volume without any distortion. So, if you want that authentic tube-driven breakup tone on a high-wattage amp, you’ll probably have your entire neighborhood shaking from sheer volume before you reach the breakup point.

This story brought to you by my 18-year-old self who thought it would be cool to get a Fender 65 Twin Reverb because it’s what the pros use, only to find out I can’t actually play the stupid thing because it blows the house down every time I turn it up above 2. Yes… I have to play it at 1.5 volume — and even then, my ears ring. Needless to say, I don’t get much breakup.

However, that brings us to the next consideration with amp wattage: headroom.

Headroom is how loud an amp can get WITHOUT breaking up. A lot of players nowadays use pedals to create their distortion/modulation/whatever rather than the amp. And if you want to play at larger venues, you need an amp that can stay clean even at high volume. My Fender Twin has an absolutely ridiculous amount of headroom…

Basically, my word of warning is to pick an amp with wattage that works for your typical play space. If you like clean tones and want lots of headroom, go for high wattage. If you want a little crunch with your tube amp, lower wattage will help you get that tone without needing earplugs.

AMS Pro Tip: Breakup only really sounds good for tube amps. Solid-state amps sound great when clean or using any of the built-in settings and/or pedals. However, when pushed to higher volume limits, the amp could begin producing a pretty harsh distorted sound. It doesn’t break up as nicely as tube amps. Let’s just say it can invoke a feeling of walking on hot, rocky sand with plenty of seashells awaiting to come into contact with your footsteps…

So, you might want to get a solid-state amp with higher wattage to avoid such a scenario. Take it from someone who maxed out the volume on an old five-watt Danelectro Cowboy amp. The entire audience had to listen to guitar playing through what sounded like a toaster oven. Burn baby burn!

Takeaway: Bigger isn’t always better.

If you’re looking for an amp to play at home or even in a small studio, a massive 150-watt monster might just be too much for the space. You won’t be able to get the full range of tones from the amp because the higher volumes would literally hurt your ears before you notice a tonal difference.

On the other side of the spectrum, if you’re playing out (especially with a drummer) and you want to be heard, you need an amp that can project to the audience without distorting your tone beyond recognition (unless you’re into that sort of thing).

Here’s basically how it works (but not set in stone):

• Practice / Bedroom (1-20 Watts): if you’re more of a bedroom/small jam settings then this will be more suitable for you. Typically, volumes hover somewhere around the 80 to 95 dB range.
• Medium-sized (20-50 Watts): small to medium sized venues are perfect for these, usually in the 95 to 110 dB range. Think about a live rock concert.
• High Power (50+ Watts): larger venues can go up to 110 dB or even higher, which is good for rock concerts and night clubs.

With that said, you don’t necessarily need a high-powered amp to play in a stadium. Many pros mic their smaller amps to maintain their smaller amp tone and get the volume they need. So even if you have a smaller amp, you can still play out!

There are also a lot of amps out there with variable power output. With the flip of a switch, you can go from full power to half power, and even down to one-watt settings. That means you can get a hefty high-wattage amp that tears the roof off live venues but can also play at quieter volumes when you want to practice in your bedroom without affecting tone.

Amps come in two main flavors: Tube and Solid State. Since we already wrote a blog about the differences between tube and solid state amps, I’ll just keep it to this: they work differently.

But that difference in their inner workings also affects their volume output.

For example, pretend you have two 50-watt amps. One is a solid state, and the other is tube. Although they’re working with identical power output, the tube amp will sound louder. This is mainly due to the natural compression in tube amps which provides more consistency in dynamic range. See?

Notice that a tube amp is slightly louder than the solid state amp in terms of output levels on this graph, despite their identical rated power outputs. This is what the listener will perceive when they hear sound coming from these amps.

A 10- or 15-watt tube amp will sound as loud or even louder than a 50-watt solid state amp! Of course, there are a lot of other aspects that go into how loud the amp will actually go, but just remember that tube amps are a lot louder with the same wattage.

For example, my Fender Twin is an 85-watt tube amp. When Fender released a solid-state amp designed to mimic the Twin (called the Tone Master Twin Reverb, in case you’re interested), it required 200 watts to match the sheer volume of the OG tube-driven Twin!

This is something you can keep in mind when choosing between amps.

Now that you know how wattage works in guitar amps, it’s time to find your perfect match! Here are just a few of our favorite amp brands to help you get started:

• Fender – American clean tone, spring reverb, great for blues, country, jazz, rock.
• Marshall – British crunch tone, iconic rock sound, great for heavy rock/metal guitarists.
• Vox – Rock, classic tone.
• Orange – Great clean and crunch sounds. Ideal for rock and metal.
• Boss - Affordable solid-state amps with a wide array of onbaord tones. 
• Line 6  - Solid-state modelling amps, customizing sound, good for all styles.

Different amps have their own unique sound, so it’s always best to try them out to find what’s right for you. You might love some but end up disliking other kinds — and that’s the fun part! Make sure you try out both the clean and overdrive settings to hear the tone from both ends of the spectrum. And don’t forget to crank it up!

And if you’re still not sure what size amp is right for you, the AMS Customer Service experts are always more than happy to provide some advice. Give us a call at 800-458-4076 to talk to a gear nerd. There are tons of amps to play with. Let’s get started!