How Loud Is That Generator? Understanding and Comparing Noise Ratings

For many, one of the most important specs of a portable generator is its noise rating — and naturally so.

Whether you’re using one in a residential area, at a campsite, or anywhere near other people, firing up a loud, roaring generator is a surefire way to earn some dirty looks.

But how exactly do you check how loud a generator really is?

The simple answer: look at the noise rating.

But — and it’s a big but — several asterisks apply. While comparing noise ratings is a fast way to get a feel for how loud different generators are, those numbers don’t tell the full story. Unless you understand how noise is measured and how to interpret decibel (dB) values, it’s easy to end up with a much noisier device than you expected.

Don’t worry — we’ve got you covered. Below, we’ll explain what noise ratings mean, how they’re measured, and what to keep in mind when comparing them.

How to Read Noise Ratings of Portable Generators

Noise rating (or noise level) is usually a single number listed in the specs of most portable generators. It tells you how loud the machine is, and is measured in decibels (dB).

But what is the decibel scale, and how should you interpret those numbers?

The Decibel Scale

The typical decibel values of sounds you encounter in your daily life lie between 0 and 150 dB.

For example, a quiet library might measure around 30 dB, normal conversation around 60 dB, and a rock concert or chainsaw can hit 110 dB or more. At the extreme end, a gunshot or jet engine can reach 140–150 dB — levels where hearing damage is almost immediate.

Everyday sounds on the decibel scale

So far, so simple. But here’s where it gets tricky:

The decibel scale is logarithmic, not linear.

What does that mean?

Logarithmic vs linear vs exponential growth

It means that each 10 dB increase represents a tenfold increase in sound power — not just a small bump in volume. For example:

• A sound at 70 dB has 10× the energy of a 60 dB sound.
• At 80 dB, it’s 100× the energy.
• At 90 dB, it’s 1000× the energy.

This logarithmic growth can be hard to grasp intuitively — and that’s before you factor in how our ears perceive sound, which is its own story.

So if Generator A is rated at 60 dB and Generator B at 70 dB, Generator B isn’t “a bit louder.” It’s 10 times more intense, and roughly twice as loud to your ears.

Sound Intensity vs. Perceived Loudness

It’s easy to assume that a 10 dB increase means something is “10 times louder,” but that’s not quite right.

• Sound intensity is a physical measurement — the actual energy of the sound wave.
• Perceived loudness is how our ears and brain interpret that energy.

In real-world terms, a 10 dB increase is generally perceived as about twice as loud by the average person. So a generator rated at 70 dB won’t sound 10 times louder than one rated at 60 dB — it will sound about twice as loud, even though it’s putting out 10× the energy.

This distinction is vital when comparing noise ratings. Two generators might differ by only a few decibels, but that can translate into a noticeable difference in how disruptive they sound in a quiet campground or residential area.

Adding Up Sound: Two Generators ≠ Twice the Noise

Now, here comes a twist.

If you’re running two generators at once, you might think they’ll be twice as loud — but not quite.

Because sound levels in decibels don’t add linearly, two identical noise sources will only raise the total noise level by about 3 dB.

Why? Because when two equal sound levels combine, they add logarithmically, not arithmetically.

So:

• 60 dB + 60 dB = 63 dB
• 70 dB + 70 dB = 73 dB

It’s a subtle but important point, especially if you plan to run multiple generators in parallel.

Increases become more significant at higher volumes, but even then, the relationship remains nonlinear. A 10 dB increase is just enough for most people to say, “Yep, that’s louder.” A 3 dB change? Often barely noticeable.

How Are Noise Ratings of Portable Generators Measured?

So, how do manufacturers measure these noise ratings?

In simple terms, a microphone (or similar sound-level meter) is aimed at the generator, and the amplitude of the sound wave is measured and compared to a standard reference. The result is expressed in decibels (dB).

Sounds simple? Not quite.

While the basic concept is straightforward, the actual testing conditions can vary significantly — and that can impact how useful the ratings really are for comparison. Even though most manufacturers follow the 23-foot distance convention when measuring noise, other aspects of the test setup can vary.

In most cases, it’s reasonable to assume that noise ratings for inverter generators are measured at 25% load, while non-inverter generators are tested at 50% load. But since this information is not always transparently disclosed by manufacturers, it should be taken with a grain of salt.

Key variables include:

• Orientation: Generators emit different noise levels depending on the direction. The exhaust side is almost always significantly louder than other sides.
• Load Level: A generator will be noticeably louder at full load than when idling or at 25% load.
• Environment: The surroundings (like walls or enclosures) can reflect or absorb sound, affecting the measurement.
• Background noise: Ambient sound in the test environment can affect the accuracy of measurement.
• Surface Type: Hard surfaces (like pavement) can reflect sound waves and raise dB readings, while grass or soft ground may dampen them.

Because there is no official government or industry-wide standard for how noise ratings should be measured — beyond the widely used 23-foot distance — some manufacturers choose to publish noise ratings at all. Without clear guidelines on factors like load, orientation, or environmental setup, noise values can vary depending on how the test was conducted.

Real-World Data: Noise vs Power Output

Understanding the theory is one thing — but seeing how real portable generators compare is even more valuable. The scatter plot below shows hundreds of portable generator models.

Each dot represents a different model. Lower on the chart means quieter. Farther right means more power.

This visualization reveals several interesting patterns:

• Inverter generators tend to cluster in the bottom-left (quiet, lower power).
• Conventional generators often push farther right and higher up (noisier, more powerful).
• A few models break the trend — delivering higher power without a huge jump in noise.

This kind of data helps you zero in on the sweet spot: maximum power with minimum noise.

Conclusion: How to Compare Noise Ratings

Let’s recap:

• The decibel scale is logarithmic, meaning small number increases represent big jumps in sound intensity.
• A 10 dB difference roughly means twice the perceived loudness.
• Two noise sources don’t double the volume — they increase it by about 3 dB.
• Noise ratings are helpful but can be misleading without the full picture (load, testing conditions, environment, etc.).
• Under 65 dB is a good rule of thumb for a generator that won’t interrupt normal conversation when within 23 feet.

Final Tip:
If your goal is quiet operation — for camping, tailgating, or use around the house — prioritize inverter generators.