CMM880 Hygrometer Review: Worth it in 2025?

This is one of the first hygrometers I worked with as a professional piano technician.

It was a trusted device for the first few years of owning it, however, I found out that it wasn't matching consistently with the other CMM880's and made me skeptical as to whether it was actually worth it.

Should you buy the CMM880 Hygrometer? 

Buy if

• You want to by a relatively inexpensive hygrometer

• You only need a hygrometer to work for a year or so

• You want a sensitive hygrometer that may not be 100% accurate

Don't buy if

• You need a hygrometer that functions accurately long term

• You can afford a better hygrometer

If you want a better hygrometer, check out the Accurate Hygrometer to monitor relative humidity/temp for pianos.

CMM880 Thermo-Hygrometer

This hygrometer seemed to work at first and was highly sensitive to changes in humidity while holding the device in my hand. It was also sensitive for when I inhaled and exhaled nearby, clearly showing that it is a sensitive instrument.

However, while it continued to be extremely sensitive to even small humidity changes, it did not stay consistent as time went on. It would fail to read consistently against the other CMM880 models I was working with.

Due to discrepancies in readings by the end of the few years using this device, my colleagues and I decided to no longer use this hygrometer by Mannix.

Comparing my old CMM880 Hygrometer

Here's a photo of the CMM880 Digital Handheld Thermo-Hygrometer.

As you can see, the CMM880 was 1.6% away in Relative humidity and 1.4 degrees away from the trusted stationary hygrometer that stays mounted on the wall.

This humidity measurement looks great at face value. However, in comparison with other hygrometers of the exact same model by Mannix, it didn't match consistently against the other devices within a few years of using this hygrometer.

When the CMM880 hygrometer is brand new it works very well. However, as time goes on it performs less accurately against the same other CMM880 models.

Is the CMM880 Hygrometer worth it?

Here's my honest opinion. It's not the best hygrometer but will work in a pinch, just not long-term.

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