A moisture meter is the single most useful tool a firewood buyer can own. They cost $20–$40, fit in a jacket pocket, and tell you in seconds whether your delivery is ready to burn. Here's what to look for and how to use one correctly.
Pin meters vs. pinless meters
There are two types of moisture meters. For firewood, you want a pin-style meter.
Pin meters work by driving two small probes into the wood and measuring electrical resistance between them. Dry wood resists electrical current; wet wood conducts it. The reading is accurate, fast, and inexpensive. Most pin meters in the $20–$40 range are more than sufficient for firewood use.
Pinless meters use radio frequency signals to scan a larger area without penetrating the wood. They're popular for flooring and building materials where you can't mark the surface. For firewood they're overkill — and more expensive. Stick with a pin meter.
What to look for
- Range up to 40%+ — some cheap meters only read up to 30%, which isn't useful for checking potentially wet wood
- Species correction table or wood/lumber mode — moisture readings vary slightly by wood density; most decent meters have a correction setting
- Pin depth of ¼ inch or more — shallow pins only read surface moisture, which dries first and can give false positives
- Simple display — digital is easier to read quickly in field conditions than analog
How to get an accurate reading
Probe the right surface
Never probe the bark — it dries faster than the interior and gives readings that are too low. Never probe a cut end — end grain releases moisture faster and also dries ahead of the rest of the wood. Instead, split a piece and probe the freshly exposed interior face. That's where the accurate moisture reading lives.
Probe perpendicular to the grain
Drive the pins perpendicular to the wood grain (across the growth rings), not parallel to it. Parallel readings run along the grain and can be inaccurate.
Test multiple pieces
Take readings from at least 5–6 pieces from different parts of the delivery — top, middle, and bottom of the pile. Dealers sometimes mix older and newer wood. A few outlier readings are normal; a consistently high average is a problem.
Account for temperature
Very cold wood reads drier than it actually is; warm wood reads wetter. If your delivery arrives in winter and has been sitting in a cold truck, let a few pieces sit indoors for 20–30 minutes before measuring for the most accurate reading.
What you're looking for
- Under 20% — ideal, ready to burn cleanly
- 20–25% — acceptable for burning, may need good draft
- 25–35% — too wet; store it for several more months before burning
- Above 35% — significantly wet; contact the dealer if you ordered seasoned wood
One more thing
If your dealer is listing moisture readings with their wood (as shown on CT Firewood Delivery listings), use your meter to verify their number when the delivery arrives. It's not about distrust — it's the same reason you weigh produce at checkout. Dealers who stand behind their readings won't mind.