A good NRR (Noise Reduction Rating) depends on how loud your environment is, but for most people, an NRR between 20 and 30 provides solid protection. The rating, printed on the packaging of earplugs and earmuffs, tells you how many decibels of noise the device can block under ideal lab conditions. The higher the number, the more sound it reduces. Most consumer hearing protection falls between NRR 15 and NRR 33.
What the NRR Number Actually Means
The Noise Reduction Rating is a single number, measured in decibels (dB), that represents how much a hearing protector reduces the noise reaching your ear. An NRR of 25, for example, means the device blocked 25 decibels of sound in laboratory testing. The scale tops out around 33 for the highest-rated products available to consumers.
Here’s the catch: the number on the label overstates real-world protection. OSHA recognized that lab conditions don’t match how people actually wear hearing protection in daily life. Workers don’t always insert earplugs correctly, earmuffs shift around, and fit varies from person to person. To account for this, OSHA strongly recommends cutting the NRR in half when estimating actual protection. So that NRR 30 earmuff? In practice, figure it’s closer to 11 or 12 decibels of real reduction after applying OSHA’s correction formula.
How OSHA’s Real-World Formula Works
OSHA’s basic calculation subtracts 7 dB from the labeled NRR, then cuts the result in half. If you’re wearing earplugs rated NRR 28 in a workplace measured at 95 dB, the math looks like this: subtract 7 from 28 to get 21, then take 50% of that (10.5), and subtract from 95. Your estimated real exposure is about 84.5 dB, which is just under the 85 dB threshold where hearing damage begins over an 8-hour shift.
That 50% correction factor is the key detail most packaging won’t tell you. It means you should always buy more protection than you think you need. If a quick calculation suggests NRR 20 is enough, go with NRR 28 or higher to build in a safety margin.
Good NRR by Activity
Different noise levels call for different ratings. Here’s a practical breakdown:
- Mowing the lawn or using power tools (85 to 100 dB): NRR 15 to 25 handles most yard work and home workshop tasks. A basic pair of foam earplugs in the NRR 22 range is usually sufficient.
- Concerts and loud events (95 to 115 dB): NRR 20 to 28 works well. Musicians’ earplugs with lower NRR ratings (12 to 20) are designed to reduce volume evenly across frequencies so music still sounds clear, which is a worthwhile tradeoff if sound quality matters to you.
- Shooting and hunting (140 to 170 dB): A minimum NRR of 25 is recommended, but NRR 30 or higher is better, especially at busy shooting ranges. Gunfire produces impulse noise that is intense enough to cause permanent hearing damage from a single unprotected shot.
- Industrial and construction work (90 to 110 dB sustained): NRR 25 to 33, depending on the specific noise levels. Because these environments involve prolonged exposure, the OSHA derating formula matters most here.
When to Double Up on Protection
For extremely loud environments, wearing earplugs underneath earmuffs provides the best available protection. This is common at indoor shooting ranges and in certain industrial settings. However, doubling up doesn’t double the protection. OSHA’s formula takes only the higher-rated device’s NRR and adds just 5 dB for the second device. Wearing NRR 33 earmuffs over NRR 29 earplugs doesn’t give you 62 dB of reduction. It gives you roughly the equivalent of NRR 38 before derating.
There’s also a physical ceiling on how much any ear-worn protection can do. At certain frequencies, sound vibrates through the bones of your skull and reaches the inner ear directly, bypassing earplugs and earmuffs entirely. Research from the Department of Defense found this bone conduction limit caps effective protection at about 40 dB in the frequency range where it matters most (around 2,000 to 3,000 Hz). No combination of ear protection can exceed that limit.
Earplugs vs. Earmuffs
Foam earplugs generally achieve higher NRR ratings (up to 33) than earmuffs (typically 22 to 31), but only when inserted correctly. You need to roll the foam tightly, pull your ear up and back to straighten the ear canal, and insert the plug deep enough that it expands to form a complete seal. A poorly inserted earplug can lose more than half its rated protection.
Earmuffs are more forgiving. You put them on, adjust the headband, and they work. They’re harder to mess up, which is why OSHA’s derating matters less for earmuffs than for earplugs in practice. The downside is that glasses, facial hair, or long hair can break the seal around the ear cup, reducing effectiveness. For people who wear glasses regularly, earplugs or specially designed earmuffs with cutouts may provide more consistent protection.
Choosing the Right NRR for You
Start by estimating how loud your environment is. A gas-powered lawn mower runs around 90 dB. A circular saw hits about 100 dB. A rock concert can reach 110 to 120 dB. A gunshot ranges from 140 to 170 dB depending on the firearm. Your goal is to reduce the noise reaching your ears to below 85 dB for sustained exposure, or as low as possible for impulse noise like gunfire.
Apply the OSHA derating to any product you’re considering. Subtract 7 from the NRR, cut the result in half, and subtract that from your estimated noise level. If the result is still above 85 dB, you need a higher-rated product or dual protection. For most people buying hearing protection for occasional use around power tools or loud events, NRR 22 to 28 covers the job well. For shooting or prolonged industrial noise, aim for NRR 30 or higher and consider doubling up with both earplugs and earmuffs.
Fit matters as much as the rating. A perfectly rated NRR 33 earplug that sits loosely in your ear canal protects less than a well-fitted NRR 25 earmuff. If you’re relying on hearing protection in a workplace setting, ask about fit testing, which measures how much noise reduction you’re actually getting with your specific ears and your specific device.