Seasoned Firewood: Moisture Content, How to Test It, and How Long It Takes

Seasoned firewood is wood that has dried to under 20% moisture content. That's the line the EPA's Burn Wise program draws, and it's the number every modern wood stove is designed around. Below it, wood lights easily, burns hot and leaves little creosote. Above it, a good part of the fire's heat goes into boiling water out of the log. Everything we sell for testing and burning firewood ships with No Sales Tax in any state.

Working out how much to buy? Our firewood calculator measures the cords in any stack and estimates how many cords you need for the winter.

What "seasoned" firewood actually means

A freshly cut tree is up to half water by weight. Seasoning is simply letting that water evaporate until the wood is dry enough to burn well. It isn't about age: a two-year-old pile of unsplit oak rounds can still be wet in the middle, while split pine stacked in the sun can be ready in a summer.

The reason the number matters is energy. Before wood can burn, the water in it has to boil off, and that heat comes out of your fire instead of your room. Wet wood also burns cool and smoky, and that smoke condenses in the chimney as creosote, the fuel for chimney fires.

Firewood moisture content chart

Take the reading from the center of a freshly split face, not the outside of the log.

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Some meter makers, including SBI, describe 18–22% as the sweet spot. In practice the advice is the same: aim for about 20% or a little under, and don't burn wood in the mid-20s or higher.

How to test firewood with a moisture meter

1. Pick a typical piece. Take one from the middle of the stack, not the top row that's had the most sun.
2. Split it. The outside of a log dries first and always reads lower than the center. A reading on the bark or the end grain will flatter wet wood.
3. Test at room temperature if you can. Frozen or very cold wood can read falsely low. Bring a split piece indoors for a few hours before testing in winter.
4. Push the pins into the fresh face. Press them in firmly near the center of the split, about halfway along the piece, and read the display.
5. Take a few readings. Test three or four pieces from different parts of the pile and go by the highest number, not the lowest.

The pins on any meter wear and bend with use, especially in dense hardwood. If readings start jumping around, swap in a fresh replacement pins kit for the Digital Firewood Moisture Reader. The reader runs on a standard 9V battery.

How to tell if firewood is seasoned without a meter

These signs point to dry wood. None of them is proof, because a log can look dry on the outside and still be wet inside:

• Cracks (checks) in the end grain radiating out from the center.
• Color: the ends turn gray or darker, and the split faces lose their fresh, bright look.
• Weight: seasoned wood is noticeably lighter than a fresh piece the same size.
• Sound: two dry pieces knocked together give a hollow ring. Wet wood gives a dull thud.
• Bark: it loosens and peels off easily.
• In the stove: wet wood hisses, bubbles sap at the ends, is hard to light and blackens the glass.

If you buy firewood, test it before you pay. "Seasoned" is often used loosely by sellers, and wood that was split a few weeks ago can still be sold that way. A meter in your pocket settles it on the spot.

How long does firewood take to season?

It depends on the species, how big the pieces are, whether they're split, and your climate. These are typical times for wood that's split, stacked off the ground with the top covered and the sides open:

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A humid or shady spot adds months. A sunny, windy one takes some off. That's why the meter matters more than the calendar.

How to season firewood faster

• Split it early. Split wood dries far faster than whole rounds. Keep pieces to about 6 inches across or smaller.
• Get it off the ground. Stack on pallets or rails so the bottom row isn't wicking up moisture.
• Cover the top, not the sides. A tarp draped down the sides traps moisture. Cover only the top, or use a woodshed with open sides.
• Give it sun and wind. Single rows with gaps between them dry faster than a big solid pile.
• Cut ahead. The easy way to always burn dry wood is to cut and split this winter's wood a year early.

Bring only a few days' worth inside at a time. An indoor holder like the Equiss freestanding log holder keeps it tidy and lets it come up to room temperature before it goes in the stove.

What wet firewood does to your stove and chimney

Every EPA-certified stove, from a compact Drolet Deco Nano N to the Englander Blue Ridge 100 N, is tested and tuned for dry wood. Burn wet wood in one and you'll see:

• Less heat. Energy goes into boiling off water.
• Black glass. A cool, smoky fire stains the door glass within hours.
• Creosote. Smoke condenses in the chimney as sticky, flammable deposits. This is the biggest safety reason to burn dry wood.
• A stove that's hard to run. Wet wood smolders when you turn the air down, which is when creosote builds fastest.

If you've been burning wet wood, have the chimney checked and swept. You can do it yourself with a chimney sweep kit; see how to clean a chimney yourself and how often to clean a chimney. Between sweeps, a creosote treatment such as Rx-Cr creosote remover or the A.W. Perkins dry creosote remover helps loosen deposits so they sweep out more easily. It doesn't replace sweeping.

A stove thermometer is the other half of the picture. It tells you when the fire is running too cool, which is when creosote builds. See wood stove temperature: what's normal.

Is kiln-dried firewood worth it?

Kiln-dried firewood has been dried in a heated chamber, usually to well under 20%. It costs more per cord, but it's ready to burn the day it arrives. It makes sense if you're new to wood heat with no seasoned stock on hand, for a cabin or occasional fire, or to mix with wood that's still a little damp. Test it anyway. A meter reading is the only proof it's as dry as the label says.

Tools for burning dry wood

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All of it ships with No Sales Tax, and free shipping on orders over $300. Questions? Email info@stovesource.com or text 1-888-866-8206.

Frequently asked questions

What moisture content should seasoned firewood be?

Under 20%, measured in the center of a freshly split piece. 15–20% is the ideal range for a wood stove.

Can you burn firewood at 25% moisture?

It will burn, but it smokes more, gives less heat and builds creosote faster. If you have to, mix it with drier wood, keep the fire hot, and check the chimney more often. Better to let it dry another few weeks.

How long does it take to season firewood?

About 6 months for softwoods and about 12 months for most hardwoods, once the wood is split and stacked off the ground with the top covered. Oak often needs 12 to 24 months.

Can seasoned firewood get wet again?

Rain wets the surface, but a top-covered stack dries back out quickly. The inside of a seasoned piece doesn't soak back up to green levels from a few days of rain. Wood left uncovered on the ground all winter, though, will pick up moisture and start to rot.

Why does my moisture meter read lower on the outside of the log?

The outside dries first. The center is always the wettest part, which is why you split a piece and test the fresh face.

Related guides

• How to Use a Wood Stove: Lighting, Air Control and Daily Operation
• How Often Should You Clean a Chimney?
• Wood Stove Temperature: What's Normal and What's Too Hot
• What EPA Certification Means on a Wood Stove
• Best Wood Pellets for Your Pellet Stove