How is impact wrench noise measured?
Under EN 62841-2-2, the part of the power tool standard that covers impact drivers and impact wrenches, as two figures. LpA is sound pressure at the operator's position, meaning the ears of whoever is working the wrench. LWA is sound power, the total the wrench puts into the garage or tire bay. A K value gives the uncertainty, and every wrench maker here puts K at 3 dB.
Each wrench's place in the ranking comes from its LpA, with the LwA quoted beside it. The DCF891B's 91 and 102 come out of one test, the first a pressure where the wrench is held and the second the tool's total power, and our page on why those two quantities differ shows why no wrench ranking mixes them.
Makers name the standard in different ways. DEWALT, Makita and Bosch print EN 62841-2-2 next to the figures. Hilti's manuals say the EN 62841 standards apply and put the exact parts in the declaration of conformity. Milwaukee's European pages give the same pair of figures with no standard at all, and that keeps them in a separate group.
Air impact wrenches fall under a different family of standards, ISO 15744 and ISO 11148-6, and none is ranked here. Anyone running air tools also has a compressor making noise behind the wrench; the air compressor guide weighs quieter compressors against how much air an impact wrench would get from each.
Which impact wrench is quietest under EN 62841?
DEWALT's DCF891B, at 91 dB(A) for the person using it and 102 for sound power. It is a mid-range 1/2 inch wrench, with 600 ft-lbs of fastening torque and 800 ft-lbs of breakaway in DEWALT's US manual.
Hilti's 12 V SIW 2-A12 follows at 92 and has the lowest sound power here, 100, but it is a 3/8 inch subcompact rated for 133 ft-lbs.
| Rank by LpA | Wrench | At the ear, dB(A) | Sound power, dB(A) |
|---|
| 1 | DEWALT DCF891B | 91 | 102 |
| 2 | Hilti SIW 2-A12 | 92 | 100 |
| 3 | Bosch GDS18V-740N | 93.5 | 101.5 |
| 4 (tie) | DEWALT DCF900B | 95 | 103 |
| 4 (tie) | Makita GWT02Z, 40V | 95 | 103 |
| 6 (tie) | Makita WT06Z, 12V max | 96 | 104 |
| 6 (tie) | Hilti SIW 4AT-22, 22 V | 96 | 104 |
| 6 (tie) | Makita TW0350, corded | 96 | 104 |
| 9 (tie) | DEWALT DCF921B, compact | 97 | 108 |
| 9 (tie) | Makita XWT17Z, 18V mid-torque | 97 | 105 |
| 11 | Bosch GDS18V-330CN | 98 | 106 |
| 12 | Makita XWT08Z, 18V high torque | 100 | 108 |
| 13 | Hilti SIW 8-22 | 101 | 109 |
The Bosch is the surprise in third, a high torque wrench rated for 740 ft-lbs. The two tied at 95 are high torque too, with 1,030 and 1,250 ft-lbs of fastening torque, and Hilti's SIW 8-22, at the bottom, carries the highest figure in this guide.
Sound power follows a similar order, with some swaps. The SIW 2-A12's 100 dB(A) is lowest, then the Bosch GDS18V-740N at 101.5 and the DEWALT DCF891B at 102. DEWALT's compact DCF921B declares 108, four more than Hilti's compact SIW 4AT-22 at 104, although the two are a decibel apart at the ear.
How loud are Milwaukee impact wrenches?
From 95.4 to 99.79 dB(A) at the operator for the three here, on Milwaukee's European pages.
Those pages give sound pressure, sound power and a 3 dB(A) uncertainty for most of the brand's wrenches, often to two decimal places.
| European model | US twin | At the ear, dB(A) | Sound power, dB(A) |
|---|
| M18 FMTIW2F12 | 2962-20 mid-torque | 95.4 | 106.4 |
| M12 FSCIWF38 | 3049-20 subcompact 3/8 inch | 97 | 105 |
| M18 FIW2F12 | 2855-20 compact 1/2 inch | 99.79 | 110.79 |
The pages do not describe the test behind these figures, and test setups that are not described cannot be compared. That keeps the three in their own group. None of them would change who is quietest overall, since the DEWALT DCF891B declares 91 dB(A) under EN62841-2-2, four decibels under Milwaukee's lowest.
Smaller drives and 12 V batteries are not automatically quieter
The 3/8 inch tools declared under EN 62841 here run from 92 to 96 dB(A). Hilti's SIW 2-A12 declares 92 dB(A); DEWALT's DCF923, the 3/8 inch sibling of the DCF921B, declares 96 in the same UK manual; Milwaukee's M12 3049-20 prints 97.
On 12 V batteries, Makita's WT06Z is the only 1/2 inch drive here, at 96.
If most of your work is small fasteners, the lightest tool is not always the quietest. Check the figure first.
More torque does not mean more noise
The Bosch GDS18V-740N declares 93.5 dB(A) with 740 ft-lbs, less than every compact 1/2 inch wrench in this guide. Makita's GWT02Z declares 95 with 1,250 ft-lbs, five decibels under the company's 18V XWT08Z, which is rated for 740. Then again, Hilti's SIW 8-22, a high torque 1/2 inch, declares the most at 101.
The hammer mechanism, the housing and the motor seem to count for as much as the torque rating, and torque alone will not predict where a wrench lands.
Impact drivers fall under the same part of the standard, and our cordless drill and impact driver guide shows how the hydraulic drivers compare with conventional ones.
Milwaukee's 2967-20 and 2562-20, DEWALT's DCF961 and Bosch's GDS18V-221N could not be ranked.
Milwaukee's EU page for the M18 FHIW2F12, the European version of the US 2967-20 high torque wrench, lists torque and speed but no noise values, and neither does the page for the M12 FCIWF38G3, the European version of the 2562-20 stubby. Two popular Milwaukee wrenches drop out that way. DEWALT's UK page for the DCF961 high torque wrench links no manual we could open, and no European twin with figures turned up for Bosch's GDS18V-221N.
All four could be quiet or loud. Not one maker document we found gives a figure for them.
Ten decibels from quietest to loudest
On a logarithmic scale that is a large gap at the ear. Yet even at 91 dB(A), the Makita, Bosch and DEWALT manuals all tell you to wear hearing protection.
A seized bolt, a long socket extension or the echo of a metal building can change what you actually hear once the wrench is in use, so the declared figure is a starting point, not a promise. Choosing a quieter wrench helps. So does using the lowest power mode that does the job, which many of these wrenches offer.
