How Loud Is a Power Sander? The Measured Spread Is Huge

The NIOSH excerpt lists orbital sanders from small triangular detail sanders drawing 60 watts up to sheet and disc sanders drawing several hundred. Loaded sound power across that group runs from about 74 dBA at the quiet end to about 93 dBA at the loud end.

A 19-decibel spread is not measurement scatter. It reflects genuinely different machines: a detail sander removing paint from a window frame and a 5-inch random-orbit sander levelling a table top are different acoustic sources despite sharing a category name.

This is the strongest argument in the dataset against "typical dB" content. When a single category's measured range covers nearly twenty decibels, quoting one figure for the category discards almost all of the information.

For sanders, several models in the dataset measured higher unloaded than loaded. That is the opposite of the intuition most people bring to power tools, and it has a physical explanation: the abrasive in contact with the workpiece damps the pad and the platen, and the motor is loaded rather than free-running.

It also matters for how specifications are read. ANSI S12.15 specifies most powered hand tools in the unloaded condition, so a manufacturer's figure may describe a state that is louder, not quieter, than real use. NIOSH published both precisely so the comparison could be made.

The practical reading is that neither figure alone characterises the tool, and the difference between them is model-specific.

Abrasive grit and pad condition change the spectrum audibly, and a worn or unbalanced pad adds a low-frequency component that a fresh one does not have. Dust extraction adds its own noise — often the dominant part of the total when a shop vacuum is attached.

The workpiece contributes as much as the tool. A large thin panel radiates the vibration the sander puts into it; a heavy damped bench does not. Two identical sanders on two different pieces do not produce the same sound at your ear.

None of these variables appear in a sound power figure, which is exactly why the figure cannot answer the practical question on its own.

The NIOSH guidance published with the tools database is stated in sound pressure: hearing protection should be worn when operating tools whose sound pressure level exceeds 85 dBA. The database's own values are sound power, so the comparison requires a measurement at the operator position — which the dataset does not provide.

Occupational criteria themselves are shift averages, not tool ratings. A loud tool used for two minutes and a moderate tool used all day can produce very different accumulated exposures, and it is the accumulation that the criteria address.

Comparisons are where a phone earns its place: pad fresh against pad worn, extraction on against off, sanding a panel against sanding a bench. Those comparisons are informative and do not depend on absolute accuracy.

Uncalibrated, our meter shows an A-weighted digital level in dBFS, which is relative rather than sound pressure. After a one-time local calibration against a trusted reference reading it shows an estimated dBA value. Neither is a sound power measurement, and neither belongs in a compliance record.