After chocolate and air, water is the most important compound we take into our bodies. Without it, there’d be no seafood, synchronized swimming or any way to cry over spilt milk. There would be no milk either. Worse, no beer! But this life giver has a dark side: mold, mildew, rot, brute force swelling and physical contortions; water can cause some serious damage. If you want a moisture meter but don’t know which one to buy, stick around. We’ll compare a range of moisture meters and help you navigate the murky waters.
Wet Behind The Ears – Choosing A Moisture Meter
The variety of moisture meters on the market can overwhelm a first time buyer. This guide should help you wade through the most common types and features you’ll encounter and help you determine which might best suit your needs.
The models we covered are intended for wood and building materials. There are specialized moisture meters made for concrete slabs (they typically require you to bore holes and embed sensors). There are also models with long probes for reaching into bales of hay, piles of grain, soil and other loose materials. But those are beyond the scope of this article.
Undetected Moisture Can Drain You Dry
Pretty much anything that can lose or absorb moisture, will: A pipe bleeding out inside the wall; A clogged air handler drain in the ceiling; Or a freeze-cracked water line under the house.
The offender loses water; your house absorbs it, inviting mold and rot. A moisture meter can help you find where the water is coming from then, later, determine if the problem has been resolved.
Wood – From Tree Meat To Bureau Bones
Wood can warp, twist, cup or bow as it dries (or if dried wood gets too wet). As moisture content goes down and up, wood shrinks and swells, respectively. Using material that hasn’t equilibrated (acclimated to the space) can end in disaster. Dimensional changes, splitting, deformation and joinery failure are all possible if you ignore moisture content.
Imagine the call you might receive if gaps started opening up between every one of the hardwood flooring strips your crew installed? Or if that newly laid carpet starts smelling musty because the subflooring wasn’t dry enough. Yeah, not good.
Pin-Type Moisture Meters – Poking Holes In Your Wood
The most common – and usually least expensive – moisture meters are pin-type. They apply a low voltage and measure electrical resistance between the pins. The pins leave a pair of tiny holes (usually not very noticeable though) and tend to only detect moisture content close to the surface. An advantage over pinless meters, however, is that they can be used on narrow edges, thinner boards and uneven surfaces.
All of the meters we cover here have LCD displays, come with batteries, have low battery indicators and auto shut-off to preserve battery life. The pin-type meters all include a cover to protect the pins from damage (and you from being stabbed by them when not in use). Beyond that, the features start to diverge.
We’ll start with the pin-type meters.
CEN-TECH / Pittsburgh – A Cheap, Surprisingly Good Meter
This one is branded “CEN-TECH”, but the exact same unit (Harbor Freight item #67143) has been sold under various names (currently, they’re branding it “Pittsburgh”).
* Type: Pin
* Modes: Wood, masonry, °C, °F
* Back light: Yes (turns off after a few seconds)
* Bar graph: No
* Hold: No
* Audible alarm: No
* Calibration checker: No
* Bluetooth: No
For the low price, this meter is pretty decent. I has three modes: wood, masonry and ambient temperature, which is useful if you want to calculate the dew point to determine what the equilibrium moisture content (“EMC”, the point at which the material would stop gaining or losing moisture) should be.
A material’s density will affect the readout on a moisture meter. As a result, if you measure a hard wood and a soft wood – both having the same moisture content – you will get two different readings. To compensate for this, most meters have settings that attenuate sensitivity. In this case, the setting is simply “wood”.
“Item 67143” is a bare bones (but usable) unit with a price to match. But if you want something a little more capable, continue reading.
General MM7 Moisture Meter With Tricolor Bar Graph
* Type: Pin (replaceable, w/extra pins included)
* Modes: Wood, building materials
* Back light: Yes (dims after 15 seconds.)
* Bar graph: Yes
* Hold: Yes
* Audible alarm: Yes
* Calibration checker: Yes
* Bluetooth: No
The General MM7 is much stouter than the CEN-TECH/Pittsburgh. It also has a nicer (and larger) LCD display, a hold function that freezes the current reading, a tricolor bar graph to show relative moisture content, and a calibration checker. But it has only two modes: “wood” and “building material”.
If you want a great entry level moisture meter, General’s MM7 is a solid choice.
General Tool Smart TS06 – A Moisture Meter W/ Bluetooth
* Type: Pin (replaceable, w/extra pins included)
* Modes: Wood, building materials
* Back light: Yes
* Bar graph: No
* Hold: Yes
* Audible alarm: Yes
* Calibration checker: Yes
* Bluetooth: Yes (used with ToolSmart app)
All of the meters we tested (except for the CEN-TECH) have a hold button you can tap to freeze the reading on the display. Unlike the others, this one is operated by your index finger.
Another thing I like about this meter is that the pin cover is tethered to the unit. So there’s no chance of losing it. The cover also contains a resistor to verify calibration. But the most note-worthy feature of this meter is its Bluetooth connectivity. Use with the General ToolSmart app to log your measurements. You can even overlay readings onto jobsite photographs, which you can then save and send to clients.
Even if you never use the app, this meter is a great choice for general (no pun intended) moisture metering. For more on this meter and the app, check out our General Tool Smart TS06 review.
General Tools MM9 Pin-Type & Pinless Moisture Meter – It’s A Hybrid!
* Type: Pin (replaceable, w/extra pins included) & pinless
* Modes: Pin-type: wood, building material; Pinless (relative only): dry wall, cement board, soft wood, hard wood
* Back light: Yes
* Bar graph: Yes
* Hold: Yes
* Audible alarm: Yes
* Calibration checker: Yes (internal)
* Bluetooth: No
This meter belongs in both the pin-type and pinless categories, so we’ll throw it here in the middle. It’s not a full-featured version of either, but the basics of both worlds wrapped up in one neat package. If you’re into construction or water damage restoration and had to choose only one moisture meter, this might be the one for you.
We’ll go into a little more detail about pinless meters shortly. But for now, know that this particular meter – when used in pinless mode – displays relative moisture content. Relative readings are used to compare one area or sample with another and have no absolute numerical value.
The idea with this meter is that you can use the pinless sensor to narrow down any areas of higher moisture (useful for tracking down sources of moisture on walls and other large surfaces). It’s the classic “hot and cold” game. Then switch to pin mode when you need an actual moisture value. Pin mode has settings for dry wall, cement board, hard wood and soft wood.
The General MM9 has a built-in re-calibration mode for the pinless function and a built-in calibration checker for the pin mode.
Pinless Moisture Meters – Non-Invasive Moisture Measuring
Pinless moisture meters don’t require you to stab the material you’re testing. Instead, they have a sensing plate that you rest flat on the surface. The plate produces an electric field and the capacitance of the material under test induces a change in that field. That change is then detected and interpreted as some level of moisture content. Pinless meters are faster, non-invasive and can sense moisture deeper than a pin-type meter might.
So why aren’t all moisture meters pinless? Well, as useful as they are, they aren’t ideal for all situations. For one, they tend to have a higher margin of error (their readings are more sensitive to ambient humidity and wood species density). Some high end pinless meters (like the Wagner Orion 950 that we’ll get to later) let you dial in the specific species of wood for higher accuracy.
Pinless meters are generally tuned to best sense moisture at or near a certain depth (usually 3/4”); the Orion addresses this issue too. They also require a flat surface, don’t really work on narrow edges and, with thin material, are easily skewed by whatever is underneath your test sample. They’re also more sensitive to knots and bits of metal.
On the plus side, pinless moisture meters are the perfect tool to quickly scan around and find higher concentrations of moisture, which is a great way to narrow down the source of a leak under a floor or in a wall or ceiling. They’re also great for other relative moisture measurements when you don’t necessarily need to know an exact numerical value. But then again, the Orion 950 has something to say about that too.
General Tools MM8 Pinless Moisture Meter – Poking Around Without The Poking
* Type: Pinless
* Modes: Drywall (relative), masonry (relative), softwood, hardwood
* Back light: Yes
* Bar graph: Yes
* Hold: Yes
* Audible alarm: Yes
* Calibration mode: Yes: auto (at power on) and Manual
* Bluetooth: No
Like most pinless meters, the General Tools MM8 Pinless Moisture Meter is factory calibrated for a depth of 3/4”, so it’s most accurate with wood at least that thick. For thinner material, you can stack several pieces. The readout automatically zeroes upon power-up, but you can manually calibrate it at any time by pressing and holding the “hold” button until calibration mode begins.
Neither the MM7, MM8 or MM9 come with instruction manuals. Luckily, downloadable PDFs of all three can be found online. Because there are some things you may never realize without it (such as that there are calibration modes and how to use them; and that some modes are actually displaying relative moisture content, not %WMC).
The General MM7 and MM9 both chirp when you press buttons (though that and the over-range alarm can be turned off if you want). The MM8, does not have the chirp; but it does have the alarm feature. The instruction manual says you can deactivate the alarm (like you can on the other two meters). But that doesn’t seem to be the case, and I’ve tried several different things many different times.
Klein Tools ET140 – A High Visibility Pinless Moisture Meter
* Type: Pinless
* Modes: Drywall (relative), masonry (relative), hardwood, softwood
* Back light: Yes
* Bar graph: Yes
* Hold: Yes
* Audible alarm: Yes
* Calibration mode: No
* Bluetooth: No
Like General Tools’ MM8 and MM9 – the Klein ET140 is factory calibrated to a depth of 3/4”. So any wood you meter should be at least that thick (if you want an accurate moisture content measurement). If it isn’t, consider stacking pieces from the same batch. Either way, lift it away from any dissimilar material to avoid false readings.
The bright safety orange surrounding the meter’s dark gray face will have you thinking this baby is protected by a rubber boot. It isn’t. What you’re seeing is just the meter’s hard plastic enclosure; it’s orange. Granted, none of the others (so far, that is) have a rubber boot. But this one looks like it does. And that would have been a really great feature.
Lacking the rubber boot it appears to have, the tapered hand grip isn’t as “grippy” as I’d like. None the less, this is probably my favorite pinless meter out of the batch.
Wagner Orion 950 – The Moisture Meter’s Moisture Meter
* Type: Pinless
* Modes: Let’s just say “all of them, and more”.
* Back light: No
* Bar graph: No
* Hold: Yes
* Audible alarm: Yes (w/programmable threshold)
* Calibration mode: Yes (Paired calibration plate included)
* Bluetooth: Yes (Use w/any of several Wagner apps)
They say you get what you pay for. Well, you get a lot with Wagner’s Orion 950 moisture meter. Way more than with any other meter we looked at. For a deeper dive into this one, check out our full Orion 950 review. There’s too much to cover here, but we’ll point out some highlights.
When it comes to features, this moisture meter does more than get its toes wet. Moisture meters typically hover around +/-2% accuracy (pinned) and +/-4% (pinless). With this meter (and the included wood species/flooring materials settings booklet), you can dial in the compensation to achieve very high accuracy.
And if that isn’t good enough for you, the meter and included calibration plate are a married pair, so you know you’re calibrating to the highest standards. No other meter we’ve covered comes even close.
The meter has built-in ambient temperature and humidity sensors and can automatically calculate EMC (Equilibrated Moisture Content). It’s capable of storing up to 100 measurements and sharing them with Wagner’s various mobile apps. And of the seven units we covered, it’s the only one with a protective rubber boot.
Surprisingly, this meter lacks one great feature that all of the others do have: a backlit display. The price and complexity of Wagner’s Orion 950 will turn off most casual users and DIYers. But some – like flooring professionals and kiln operators who demand the best – will find it worth every penny.
Cut And Dry – Some Final Words
Finally, a note regarding the visibility of LCD displays: The backlit, reverse contrast displays of the Klein and General Tools “MM” series meters are exceptionally easy to read most of the time. But they can be difficult to impossible to make out under direct sunlight. Conversely, the reflective lighting of the Orion and CEN-TECH (after a few seconds, once the back light turns off) are most visible under bright lighting conditions.
In the end, all of these meters work pretty well. The one that’s right for you – whether it’s one of these or any of the many others on the market – depends on your needs and budget. But at least now when you shop for a moisture meter you won’t feel so much like a fish out of water!
Further Reading and Purchase Links
How Temperature & Humidity are Related:
What Is Equilibrium Moisture Content, And Why Is It Important?
Understanding Moisture Content in Wood:
Purchase CEN-TECH (Pittsburgh) #67143 pin-type moisture meter for under $14:
Purchase General Tools MM7 Pin-Type Moisture Meter for under $35:
Purchase General Tools ToolSmart Bluetooth Connected Digital Moisture Meter for under $35:
Purchase General Tools MM9 Combination Pin & Pinless Moisture Meter for under $55:
Purchase General Tools’ MM8 Professional Digital Pinless Moisture Meter with Backlit LCD for under $45:
Purchase Klein Tools’ ET140 Pinless Moisture Meter for under $40:
Purchase Wagner Meters’ Orion 950 for under $540:
