In federal and university tests, a suppressed .22 rifle peaked at about 118 to 120 decibels at the shooter’s ear. A suppressed .223 rifle peaked at 122 to 134, and a suppressed .308 at 131 to 137. The same guns without a suppressor measured 140 to 161. So a suppressor takes off roughly 17 to 26 decibels, and a suppressed rifle is still louder than most people expect.
This post is about the numbers for specific setups and why they differ. For whether those numbers are safe for your ears, read are suppressors hearing safe. All figures here come from peer-reviewed and government research, checked as of November 2026.
How loud is a suppressed gun? The tested numbers
The best public data set we found comes from a study published in the International Journal of Audiology, “The reduction of gunshot noise and auditory risk through the use of firearm suppressors and low-velocity ammunition”. The authors work at NIOSH, the federal hearing research agency, and at several universities. They tested four firearms, a .22 pistol and three rifles, with and without suppressors, and put microphones at the shooter’s ears, at the muzzle and about a meter behind the shooter.
The table shows peak sound at the shooter’s left ear and at the spot about a meter behind. “Low velocity” and “high velocity” mean two kinds of ammunition for the same gun. The rated speeds were 1,050 and 1,280 feet per second for the .22 rifle, 1,000 and 3,240 for the .223 and 990 and 2,670 for the .308. The .22 pistol was tested with the fast ammunition only.
| Setup | Ammunition | Shooter’s ear, without | Shooter’s ear, with | A meter behind, without | A meter behind, with |
|---|---|---|---|---|---|
| .22 pistol | High velocity | 152 dB | 128 dB | 135 dB | 113 dB |
| .22 rifle | Low velocity | 140 dB | 118 dB | 123 dB | 103 dB |
| .22 rifle | High velocity | 141 dB | 120 dB | 125 dB | 105 dB |
| .223 rifle | Low velocity | 140 dB | 122 dB | 127 dB | 100 dB |
| .223 rifle | High velocity | 160 dB | 134 dB | 148 dB | 120 dB |
| .308 rifle | Low velocity | 148 dB | 131 dB | 134 dB | 111 dB |
| .308 rifle | High velocity | 161 dB | 137 dB | 150 dB | 123 dB |
For scale, NIOSH recommends that a single loud sound never go above 140 decibels, and it measured firearm peaks from 144 decibels for a .22 rifle to 172 for a .357 revolver. A decibel is not a straight-line number. NIOSH notes that a sound 10 decibels louder is ten times more intense.
What the numbers show
Three patterns stand out.
Bigger guns are louder, even suppressed. The suppressed .22 rifle read 118 to 120 decibels at the ear. The suppressed .223 with fast ammunition read 134 and the .308 read 137. The suppressor helped every gun by roughly the same amount, so the louder gun stayed louder.
Slower ammunition is quieter. In every pair, low-velocity ammunition read lower than high-velocity ammunition in the same gun. The bigger the gun, the bigger the gap. The suppressed .223 went from 134 decibels with fast rounds to 122 with slow ones. Combining a suppressor with slow ammunition, the authors say, did better than the two effects added together.
The suppressor cut 17 to 24 decibels at the ear. That is the authors’ range for the shooter’s ears across all the test guns. Behind the shooter, the cut was 20 to 28 decibels. The left ear alone showed up to 26 on the fast .223 test, from 160 down to 134.
Why a fast bullet still makes noise
A gunshot has two main sounds. One is the blast from the muzzle, which a suppressor is built to trap and slow. The other is a sharp crack made by the bullet itself when it flies faster than the speed of sound. A suppressor cannot remove that second sound, because the bullet makes it in the air after it leaves the barrel.
The study measured this a second way, with a half-sphere of microphones 3 meters out that captured the total sound a gun puts out in every direction. For the .22 rifle with slow ammunition, the suppressor cut that total sound power by 16 decibels. With fast ammunition, it cut it by only 2. The authors say the larger cuts with slower ammunition are due to the shock waves that a supersonic bullet makes. For the .22 pistol, the cut was 23 decibels with slow ammunition and 15 with fast.
That is why people say “subsonic” when they talk about quiet shooting. For more on how ammunition and the first shot behave, see our posts on the first round pop and the .22 suppressor.
Where you measure matters
Look at the table again. The same shot read 160 decibels at the ear, 148 a meter behind and more at the muzzle end. In the study, unsuppressed peaks at the muzzle microphone ran from 149 to 176 decibels, and suppressed ones from 128 to 150. A number with no location attached tells you very little.
Other things change it too. The paper’s review of earlier work found that on semi-automatic rifles with a gas port, the cut at the shooter’s right ear was smaller, about 10 to 18 decibels, because gas escapes near that ear. Bolt-action rifles in this study showed no such gap between the ears.
Why manufacturer numbers do not line up
If you have looked at suppressors online, you have seen a decibel rating for each. Those numbers are real measurements, but they are hard to compare, because there is no agreed test. A later NIOSH-led paper, “Developing a method to assess noise reduction of firearm suppressors for small-caliber weapons”, states that the American National Standards Institute has no suppressor testing standard. It tested 14 firearms with microphones in a ring 3 meters from the muzzle, with high-velocity and low-velocity ammunition, and found peak cuts from 3 to 28 decibels, depending on the setup. That is a wide spread from the same kind of device.
So when you read a rating, ask what it was measured on and how:
- Which gun and which ammunition? A number on a .22 with slow rounds says little about a rifle with fast ones.
- Where was the microphone? At the muzzle, at the ear or off to the side all read differently.
- What was it measured against? A cut is the difference from the same gun without a suppressor, so what that bare gun reads matters as much.
- Is it a peak or an average? The study found that peak numbers do not always capture the whole effect. The paper measured both peak and an energy figure, and the cuts did not match.
A real range of 3 to 28 decibels is a reminder that no single figure fits every setup. We do not have measured numbers for a 9 millimeter pistol suppressor from a peer-reviewed source to quote here, so we are not going to guess. If you want to compare cans for a pistol, our pistol suppressor guide explains what to look for.
What this means when you buy
A suppressor lowers the sound of your gun by a meaningful amount, roughly the size of the drop in the table, and the ammunition you shoot can matter nearly as much as the can. It does not make a gun quiet enough to shoot without ear protection, and the ratings you read online are not on one scale. The honest answer to “how loud” is that it depends on the gun, the ammunition and where you stand.
That is easy to talk through in person. Come by our shop in Cumming, tell us what you shoot, and we will walk you through what to expect and how the Form 4 process works, with the forms and fingerprints done in the shop. Read how it works on our suppressor page, or send us a question before you drive over.
Sources: Int J Audiol 2018 (PubMed 29299940), NIOSH’s guidance for hunters and shooters (CDC Stacks 185948), and Proceedings of Meetings on Acoustics 2018 (CDC Stacks 221679).
