How to Use a Moisture Meter on Firewood the Right Way

Knowing how to use a moisture meter on firewood matters more than which meter you own, because the most common way people burn wet wood is by testing dry wood wrongly. Press the pins into the outside of a log and it will read low, because the surface is always drier than the core that actually burns. Do it properly and a cheap meter tells you the truth. This guide walks through the correct method step by step, so you never load the stove on a false reading again.

Why you must split the log first

The single rule that makes everything else work: split the log and test the freshly exposed inner face. The outside of a log dries out fastest, so a reading taken on the weathered surface, the sawn end, or the bark can show 15% while the middle is still soaking at 30%. That damp core is what you are really burning, and it is what a moisture meter needs to measure.

So take the log you want to test, split it, and immediately test the fresh face near the centre. Do not test the end grain, which also reads unreliably, and do not test a log that has been sitting split for hours, because that face will have started drying too. Fresh split, straight to the meter.

Step by step

1. Bring the wood to room temperature. Cold wood reads inaccurately on meters without temperature compensation, so a log brought in from a frozen stack should sit indoors for a few hours first. Test at roughly room temperature for a fair reading.
2. Split a log to expose a fresh inner face. Aim to reach the middle, the part that dries last.
3. Wipe the face. Even a little surface moisture skews the result, so wipe the fresh face clean and dry before you touch it with the meter.
4. Set the meter to wood. If your meter has wood species or group settings, choose the correct one; a generic setting is fine for a rough check but species selection is more accurate.
5. Press the pins into the fresh face. Push both pins firmly in until they are buried to at least half their length, on the freshly split middle of the log. Take the reading once the number settles.
6. Test three spots. Read the middle of the split and near each end, then move to another log. Take a reading, not one lucky reading.

Take several readings, not one

Moisture varies from log to log and even within a single log, so one measurement tells you almost nothing. Pull a handful of logs from different parts of the stack, the top, the middle and the back, and test each on a fresh face. If most read under 20% you are good to burn; if several are still high, the whole batch needs longer to season. Trusting one convenient log is exactly how people end up burning wet wood and tarring up a flue.

What the number should say

The target is simple: under 20% moisture means ready to burn. This is not just good practice, it is the legal standard in the UK. Wood sold in volumes under two cubic metres must be certified as having 20% moisture or less under the Ready to Burn scheme, precisely because wet wood wastes heat, produces far more smoke and creosote, and dirties your glass and chimney. Anything meaningfully above 20% should go back on the pile.

If your readings keep coming in high, the wood simply is not seasoned yet, and no technique will change that. Our guide on what moisture firewood should be explains the 20% rule in full, and if your meter is giving suspiciously high numbers, why a moisture meter reads too high covers the usual culprits. For the wider legal picture, Woodsure, which runs the certification, sets out the Ready to Burn requirements.

Pin depth and meter type

Most firewood meters are pin type, and that is the right tool for logs. The pins read the moisture at the depth they reach, so pressing them properly into a fresh split face is what gives an honest core reading. Pinless meters, which scan below a flat surface, are designed for boards and flooring and are easily fooled by the irregular shape of split logs, so they are not the tool here. Our pin versus pinless comparison explains why, and the moisture meter buying guide covers what to look for if you have not bought one yet.

Get into the habit of splitting, wiping and testing the fresh face, and a meter that costs very little will keep you burning dry, efficient wood all season.

Frequently asked questions

Where do you test firewood with a moisture meter? On a freshly split inner face, near the centre of the log. Never test the outside, the bark or the sawn end, because those dry out first and read far lower than the damp core that actually burns.

Do you push the pins along or across the grain? Press the pins firmly into the fresh split face until they are at least half buried. Take readings in three spots, the middle and near each end, then repeat on other logs to get a true picture of the batch.

What moisture reading is safe to burn? Under 20%. That is both the efficient level and the UK legal standard for firewood sold in small volumes under the Ready to Burn scheme. Wood above 20% wastes heat, smokes more and builds creosote in the flue.

Do I need to warm the firewood before testing? Yes, if it is cold. Meters without temperature compensation read inaccurately on frozen or very cold wood, so bring a log indoors to roughly room temperature for a few hours before you test it.

Why does my dry-looking wood read wet in the middle? Because logs dry from the outside in. The surface can feel and read dry while the core is still seasoning, which is exactly why you split the log and test the fresh inner face rather than the outside.