Kiln-dried vs. seasoned firewood comes down to moisture. Kiln-dried logs are dried with heat to below 20% moisture and are ready to burn. Seasoned logs are air-dried for months, often reach about 20 to 30%, and vary more. Kiln-dried costs more per kilogram, but it burns hotter and cleaner. Here is how they compare and how to test yours.

What is the difference between kiln-dried and seasoned firewood?

Seasoned firewood is wood that has dried naturally in the open air, usually stacked off the ground for six months to two years. Kiln-dried firewood is dried in a chamber with controlled heat and airflow, which takes days rather than months. The result is a more predictable moisture level.

Freshly cut wood contains between 50% and over 100% moisture on a dry-weight basis, according to the University of New Hampshire Cooperative Extension. The same source puts air-dried wood at generally around 30% and kiln-dried wood at less than 20%. The ideal range for burning is below 20%, so seasoned wood often needs extra drying before it reaches that point.

The word “seasoned” has no legal definition in most countries. A seller can call logs seasoned after a few weeks. Ask for a moisture figure, or measure it yourself.

How much moisture should firewood have?

Wood burns best at a moisture content below 20%. The US EPA Burn Wise guidance recommends below 20 per cent and at least six months of seasoning. The New Hampshire Department of Environmental Services says wood is only ready to burn at 20% or less and advises assuming that seasoned wood is not ready without further drying.

Wood type	Typical moisture	Ready to burn?
Freshly cut (green)	50% or more	No
Seasoned, 6 to 12 months outdoors	about 25 to 35%	Often not yet
Well-seasoned, 18 to 24 months, covered	about 18 to 25%	Usually yes.
Kiln-dried	below 20%, often 12 to 18%	Yes.

These are typical values, not guarantees. Drying time depends on species, split size, climate and stacking. Dense hardwoods such as oak take the longest.

Which gives more heat?

Moisture reduces usable heat because part of the energy evaporates the water in the wood instead of heating your room. Dry wood at about 15 to 20% moisture gives roughly 4.0 to 4.2 kWh per kilogram. Wood at 30% gives roughly 3.4 kWh per kilogram. These figures are approximate and vary by species.

That is a gap of about 15 to 20% per kilogram. In practice the difference is larger, because wetter wood lowers the flame temperature and the stove loses efficiency. You burn more logs for the same heat, and you clean the glass and chimney more often.

How do they burn?

Kiln-dried logs light easily and burn with a bright, steady flame and little smoke. Wet wood hisses, smokes and leaves black glass. According to the New Hampshire Department of Environmental Services, burning wet wood releases pollution and creosote in your chimney, which can create a fire hazard.

Seasoned logs that are properly dry burn almost as well. The difference is consistency. A batch of kiln-dried logs behaves the same from the first to the last log. A batch of seasoned logs may include a few that are still damp, so you adjust the air control more often.

How do prices compare?

Kiln-dried firewood usually costs more per kilogram because the drying uses energy and equipment. Seasoned wood is cheaper to produce, but you often pay for storage time. The price gap varies by country, species and quantity, so compare quotes on a like-for-like basis.

The fair comparison is cost per kWh of heat, not cost per bag or per tonne. The table below uses example prices only. They are not our prices.

Example	Example price per tonne	Heat per kg	Cost per kWh
Seasoned, 30% moisture	180 EUR	about 3.4 kWh	about 0.053 EUR
Kiln-dried, 18% moisture	230 EUR	about 4.1 kWh	about 0.056 EUR

With these example prices the cost per kWh is almost equal, and the kiln-dried logs give cleaner burning, less ash handling and no wait. If the seasoned price is much lower or the logs are truly below 20%, seasoned wood can be the cheaper choice. Always weigh up the real moisture figure, not the label.

Also check how the wood is sold. Firewood is sold by weight, by the stere, by the loose cubic metre, or by the bag, and the same price can mean very different amounts of wood.

How should you store each type?

Store both types off the ground, under a roof, with open sides for airflow. Kiln-dried logs dry out to a low moisture level in the kiln, but they absorb moisture again from damp air and rain if left uncovered. In a humid climate they can climb back above 20% over a few weeks outdoors.

Seasoned logs need airflow even more, because they are still drying. Stack them in a sunny, windy spot, with the top covered. UNH recommends racking the wood off the ground in an open location with airflow on all sides. Keep a small supply near the stove for a day or two so the logs are room temperature before burning. Our guide on how to store firewood the right way gives the full stacking method.

How do you test firewood with a moisture meter?

A pin-type moisture meter costs roughly 15 to 30 EUR and gives a reading in seconds. Use it like this:

Take a log from the middle of the pile, not from the outside layer.
Split it in half. Measure on the fresh surface, not on the bark or the outer face.
Push the pins into the wood along the grain, not across it. Press them in firmly.
Take readings from three or four spots on the split face and from at least five logs.
Take the average. Burn if it is below 20%. If the reading is higher, dry the wood longer.

Bring the logs indoors for a few hours before testing, because cold logs can read incorrectly. If your meter has species settings, select the closest one. Treat the result as a good estimate, not a laboratory measurement.

You can also check by eye and by weight. Dry wood looks darker, has cracks in the ends, weighs less than green wood and sounds hollow when you knock two logs together. These signs help, but they are less reliable than a meter.

Which species should you buy?

Species matters because dense hardwoods hold more energy per log but dry more slowly. That is a reason to buy kiln-dried hardwood instead of waiting for it to season. Our dried firewood is listed with moisture below 18%. For specific species, we offer beech, hornbeam, ash and alder firewood. If you want help choosing, read our comparison of oak, hornbeam, beech and kiln-dried logs.

Which should you choose?

Choose kiln-dried if you need to burn soon, if you have limited storage space, or if you want consistent logs for a modern stove. Choose seasoned if you have space and time to let it dry; you can buy it at a clearly lower price, and you will test it with a meter before use.

A practical approach is to buy a small amount of kiln-dried wood for the start of the season and order seasoned or green wood in spring for the following winter. We deliver across Europe. If you are not sure, see our dried firewood and test a delivery with your own meter.

Key takeaways on kiln-dried vs. seasoned firewood

Kiln-dried firewood is below 20% moisture and ready to burn. Seasoned wood is often 20 to 30% and varies.
Wood burns best below 20% moisture. Check with a meter.
Dry wood gives about 4.0 to 4.2 kWh/kg; wood at 30% is about 3.4 kWh/kg.
Compare cost per kWh, not price per tonne or bag.
Store both types raised, covered and ventilated.
Test five logs from the middle of the pile on a freshly split face.

FAQ

Is kiln-dried firewood worth the extra cost?

Often yes, especially if you need dry wood now. It saves drying time, burns cleanly and gives consistent results. If seasoned wood is cheap and tests below 20%, it can be equally good value.

How long does it take to season firewood?

Green wood typically needs 6 to 12 months, depending on species and conditions, and dense hardwoods can need up to two years. Split small, stack in a windy place and cover only the top.

Can I burn seasoned firewood straight away?

Only if it tests below 20%. Many logs sold as seasoned are above that. Measure first, and dry them longer if needed.

Does kiln-dried wood burn too fast?

No. Burn rate depends on species, log size and air setting. Dry hardwood logs burn at a steady rate when you set the air control correctly.

Can kiln-dried logs get wet again?

Yes. They take up moisture from rain and humid air. Keep them covered and ventilated, and recheck with a meter before burning if they were stored outdoors for a long time.

Kiln-Dried vs Seasoned Firewood: Moisture, Price, Heat and Storage