How loud are woodworking tools? I measured my shop and did the math
After my hearing test I wanted numbers, not warnings. How loud is the planer, really? How long can I run the table saw before it starts costing me? So I downloaded a sound level meter app, stood where I normally stand, and measured every machine in the shop. Then I looked up what the federal rules say those numbers mean.
The answer was worse than I expected for the big machines and better than I expected for a couple of the small ones.
A word about phone apps
I used the NIOSH Sound Level Meter app on an iPhone. NIOSH is the federal agency behind the workplace noise research, and it released its own app a few years after testing a pile of other people's. In a 2014 study in the Journal of the Acoustical Society of America, two NIOSH researchers checked more than 130 iPhone apps and found only a handful accurate enough to evaluate properly, with the best within about half a decibel of a lab meter and two more within 2 dB. Most Android apps they looked at didn't make the cut at the time.
So treat my readings as good ballpark figures, within a couple of decibels, not laboratory measurements. That's close enough to make decisions with.
My readings
All A-weighted (dBA), measured at my ear while I worked, rounded to the nearest decibel. Your tools, blades and shop will differ.
| Tool or situation | My reading | Notes |
|---|---|---|
| Thickness planer, 6-inch white oak | 101 dBA | Loudest thing I own |
| Circular saw, ripping plywood | 99 dBA | Outdoors it was a bit lower |
| Miter saw, crosscutting maple | 98 dBA | Short bursts |
| Table saw, ripping 3/4-inch oak | 97 dBA | Idling it was about 85 |
| Router table, profile bit | 95 dBA | Higher with a big panel bit |
| Air compressor running | 88 dBA | Now lives outside the shop wall |
| Random orbit sander | 87 dBA | Lower than I expected |
| Shop vac | 86 dBA | Annoyingly close to the line |
| Dust collector, in the open shop | 84 dBA | 76 dBA after I built a closet for it |
| Radio, the way I used to play it | 82 dBA | Loud enough to hear over the vac |
What those numbers mean in minutes
Decibels aren't like inches. Every 3 dB is twice the sound energy. OSHA's noise page explains that NIOSH recommends keeping exposure below 85 dBA averaged over 8 hours, and that every 3 dB above that cuts the safe time in half. Here's what that rule works out to.
NIOSH recommended exposure limit: 85 dBA for 8 hours, halving with every 3 dB. Total for the whole day, not per tool.
| Sound level | Time per day |
|---|---|
| 85 dBA | 8 hours |
| 88 dBA | 4 hours |
| 91 dBA | 2 hours |
| 94 dBA | 1 hour |
| 97 dBA | 30 minutes |
| 100 dBA | 15 minutes |
| 103 dBA | 7.5 minutes |
Source: OSHA occupational noise page, NIOSH recommended exposure limit; minutes are my arithmetic.
So my table saw, at 97 dBA, uses up a whole day's safe dose in about half an hour. The planer gets there in about twelve minutes. Ten minutes of planing is nothing. I'd plane for an hour straight on a big job.
Why the OSHA number is different
You'll also see 90 dBA quoted. That's OSHA's legal limit for workplaces, and it uses a 5 dB rule instead of 3 dB. NIOSH, which does the research, says that's not protective enough. The gap gets big quickly:
| Level | NIOSH recommended limit | OSHA legal limit |
|---|---|---|
| 85 dBA | 8 hours | 16 hours |
| 90 dBA | About 2 1/2 hours | 8 hours |
| 95 dBA | About 47 minutes | 4 hours |
| 100 dBA | 15 minutes | 2 hours |
| 105 dBA | About 5 minutes | 1 hour |
I go by the NIOSH numbers. OSHA's limit is about what an employer can be cited for. NIOSH's is about what your ears can take. The OSHA technical manual chapter on noise explains how noise dose is calculated if you want to get into the weeds, including how different tools across a day add up.
Where my damage showed up
My hearing test showed the loss bunched up in the high pitches, worst around 4,000 Hz. That's the classic sign of noise, and it's why I can hear a customer talking but miss half the words. The consonants live up there. If your test looks like that, this explainer on what high-frequency hearing loss is and how it's treated walks through hearing aids, communication tricks and stopping it from getting worse.
The NIDCD's page on noise-induced hearing loss has the plain version: sounds at or below 70 dBA are unlikely to cause damage, and long or repeated exposure at 85 dBA and up can. Every machine in my shop except the dust collector in its closet is over that line.
Measuring your own shop
If you want your own numbers, here's how I did it so the readings mean something:
- Use an app that's been checked against a real meter, and set it to A-weighting (dBA). Take your phone case off if it covers the microphone.
- Hold the phone where your ear is when you work, not at the machine and not across the room. Distance changes the reading a lot.
- Measure while actually cutting, not idling. My table saw idled at 85 and cut at 97.
- Take the average over a typical cut, not the peak. The app shows both.
- Write down what you were cutting. Hardwood, wide boards and dull blades all read louder.
- Measure the background too, with nothing running. That's what your ears get between cuts, and in a lot of shops it's higher than people think.
Then add it up the way a day actually goes. A morning of planing, sawing and sanding can use up several days' worth of the NIOSH dose before lunch, even if no single tool runs very long.
What I changed after measuring
The measuring was the useful part. It told me where to spend effort:
- The planer and the saws always get earmuffs, even for one cut. One cut turns into ten.
- The air compressor moved outside, in a small insulated box with a vent. That took 88 dBA out of the room.
- The dust collector went into a closet lined with leftover insulation. 84 down to 76.
- The radio stays off while machines run. I was adding noise to hear noise.
- I batch the loud work. All the planing in one session with muffs on, rather than ten minutes here and there all day.
I've been reading a hearing site, improvehearingnaturally.com, that covers the rest of ear health in the same no-nonsense way. But the biggest lesson from the app is simple. If you have to raise your voice to talk to someone three feet away, it's loud enough to hurt you, and you don't need an app to know that.