How Long Does Firewood Burn? A Quick Guide

For most of us, it’s a pet peeve to constantly add more wood to keep the fire in a fireplace, campfire or wood-burning stove. How long do we actually expect the fire to last?

We’ve got your back! In this article, we’ll answer all your questions about firewood burn times and which types burn the longest. Read on!

How long does firewood burn?

On average, a piece of firewood can burn for 2 to 8 hours, depending on the wood’s density. The denser the firewood, the more fuel it has to keep it burning.

Firewood which is dense and adequately seasoned burns the longest and slowest because they have more wood packed in every inch, taking it longer for fire to get through them.

Here’s a table of the most common firewood and their densities for your reference.

Firewood	Density (lbs/ft.)
Apple	41 to 52
Ash	40 to 53
Beech	32 to 56
Black Locust	42 to 44
Cherry	43 to 56
Elm	35
Hickory	37 to 58
Maple	39 to 47
Oak	37 to 56
Sycamore	24 to 37

Based on the table above, hickory is the slowest burning firewood, with a density ranging from 37 to 58 lbs/ft. 

Hickory also burns a lot of heat, producing 28 million BTUs per cord. One hickory log can burn for about 4 hours, so you’ll only need to refuel the fire once or twice throughout the evening. 

Ash is also a popular choice for slow-burning firewood because of its fast seasoning time and abundance in the market. Other slow-burning firewood includes beech, black locust and oak. 

What are burn times?

Burn times refer to the total time for a piece of wood to burn from ignition to smoldering. It includes the time the wood is kindled until extinguished, as when a new log can no longer catch fire from the existing embers. 

Burn times highly depend on the firewood’s BTU count (heat output) and the fireplace setting. 

BTU count pertains to the maximum heat a piece of wood can produce. On the other hand, the fireplace setting refers to high or low burning.

Putting these two together, burn time then means the maximum amount that a fireplace can burn under ideal conditions. So, if you burn a piece of wood on a high setting, it will produce its maximum heat capacity but will burn quickly. 

On average, a piece of wood burned in a high setting can produce 55,000 BTUs and burn in 2 and a half hours. Conversely, burning the same piece of wood in a low setting will have 18,000 BTUs and burn for 8 hours. 

Factors That Affect Burn Times

Burn times are primarily affected by the type of wood, moisture content, burn settings, and climate conditions.

Let’s talk about how each affects the burning of firewood.

1. Type of Wood

Generally, hardwoods burn longer than softwoods. For instance, hardwoods like walnut, hickory and oak burn longer than softwoods such as fir and pine. 

Hardwood trees are primarily deciduous, meaning they have broad leaves, lose their leaves during winter, and produce less sap than softwoods. 

Softwood trees, on the other hand, are coniferous trees with needle-like leaves and produce more sap or resin when opened. 

Denser hardwoods burn slower and produce less smoke and more heat energy than softwoods. They’re best for fireplaces and wood-burning stoves.

But that’s not to say that softwoods are useless. On the contrary, they make great fire starters on campfires because of the sap or resin in them.

2. Moisture Content

You’ll get longer burn times when you use unseasoned firewood because they’ll likely burn longer but with less heat. This is because most of its energy evaporates the remaining moisture during combustion. 

So if you want your firewood to burn longer and produce more heat, make sure it’s well-seasoned to keep the wood’s energy on creating heat for a longer time. 

Follow the rule of thumb in firewood burning: only use firewood with less than 20% of moisture content.

3. Fireplace Setting

If there’s a lot of airflow in your fireplace, the tendency is the wood will burn hotter but for a short amount of time. The fire can consume as much oxygen as possible while using all its available fuel quicker than expected.  

You can restrict the airflow near the fire if you want a longer burn time. This way, the low airflow fires will burn at a lower heat output for longer hours.

4. Climate

High altitude and high humidity cause less oxygen around the fireplace. If there’s less oxygen, it will reduce the burning efficiency of the firewood and will result in shorter burn times.

What are the slowest burning firewoods?

Here’s a table of the top 10 slowest burning firewood available, with their burn times and recommended uses.

Firewood	BTU per cord	Burning Hours	Best Used In
Oak	27 million	6 to 8 hours	• Wood-burning stove
Maple	25 million	4 to 7 hours	• Wood-burning stove • Campfire
Ash	24 million	6 to 8 hours	• Wood-burning stove
Hickory	28 million	4 hours	• Fireplace • Wood-burning stove
Cherry	20 million	5 to 7 hours	• Fireplace • Wood-burning stove • Campfire
Apple	27 million	6 to 8 hours	• Fireplace • Wood-burning stove • Campfire
Hornbeam	27 million	6 to 8 hours	• Fireplace • Wood-burning stove
Walnut	22 million	4 to 6 hours	• Fireplace • Campfire
Hawthorn	25 million	4 to 7 hours	• Fireplace • Wood-burning stove • Campfire
Osage orange	34 million	6 to 8 hours	• Campfire

How to Make Firewood Burn Longer

When burning firewood, we’re all for maximizing their burn time. We’ve wrapped up our four proven and tested tips on how to make any firewood burn longer. 

1. Provide ventilation.

Make sure that your fireplace provides the right amount of ventilation. Fire needs oxygen, and proper ventilation allows it to keep burning. 

If you’re in a fireplace, open an air dampener to allow cool air to move over the fire but make sure that the hot, smoky air is released through your chimney. 

Ventilation is also affected by the cleanliness of your chimney. If there’s too much creosote buildup, that black tar-like substance in your chimney, airflow is limited, and it will prevent the fire from burning steadily. 

2. Do reverse stacking.

Difficulty	Easy ●○○○○
Duration	30 minutes to 1 hour
Things You Need	• Logs • Axe

Reverse stacking is an effective way to build a fire correctly. The fire you created on the top of the stack will burn downwards, and as a result, it will be fueled by the layers underneath it.

Because the reverse stack is stable, the fire will burn evenly. Depending on the wood, each layer translates to about 25 to 35 minutes of burn time.

We also highly recommend that you place the larger logs at the bottom. This way, as the fire burns downwards, the large logs can make the fire last longer.

Here’s how to do reverse stacking. 

How to Do 1. Gather logs that are between 5 to 8 inches in diameter. 2. Using an axe, split these logs in the middle. 3. Alternately stack the halved wood – cut side up and exterior side down – until you form a flat surface. 4. Continue to build the layers of your reverse stack. Always add a new layer perpendicular to the previous layer.

3. Use warm wood.

Warm wood burns hotter and longer. So, don’t leave them out in the cold and keep them warm in your home, barn or a dry storage place.

Refrain from using cold wood because it takes a long time to ignite, which means it also takes a lot of energy to start burning. You might end up with a fire going out too quickly in the long run. 

4. Season wood properly.

Seasoning firewood is important because it allows most of its moisture to evaporate. So, when you use it to start a fire, it will burn cleanly and efficiently. 

However, if you use unseasoned firewood, it still contains high moisture content, and we don’t want that because it will use up more energy to ignite and produce more smoke.

Below is a table of the tem common firewood and their good seasoning and burning features.

Firewood	BTU per cord	Seasoning Time	Splitting	Ignition
Hickory	28 million	12 months	No	Fair
Oak	28 million	24 months	Yes	Poor
Beech	27 million	6 months	No	Poor
Cherry	20 million	6 to 12 months	Yes	Poor
Ash	24 million	6 months	Yes	Fair
Black Locust	27 million	12 months	No	Poor
Apple	27 million	12 months	No	Poor
Maple	26 million	12 to 24 months	Yes	Poor
Elm	20 million	12 months	No	Fair
Sycamore	20 million	60 to 12 months	No	Fair

How can you tell if firewood is bad?

Generally, bad firewood has holes, molds, crumbles and burns quickly. Good firewood has less than 20% moisture and burns longer. 

Here’s a quick comparison table to help you out:

Good Firewood	Bad Firewood
Has cracks forming with lighter weight	Has molds and holes
Less than 20% moisture content	60% or more moisture content
Ringing sound	Dull sound
Burns longer	Burns quickly

Seasoned firewood can last about 3 to 4 years before losing its efficiency in burning. To achieve this, you’ll have to keep them dry.

Firewood usually rots and crumbles when left on the ground or stored in a wet place. But if the firewood has less than 20% of its moisture content, fungus, bugs and termites will not take hold of your firewood.

Good firewood is also lighter in weight and develops cracks due to water loss during the seasoning period. 

Another way to tell which is good firewood is by hitting two pieces together. If you hear a ringing sound, that’s good firewood, while if you hear a dull thud, it’s unseasoned firewood because water absorbed the sound.

How long can firewood be stored?

Generally, firewood can be stored for 3 to 4 years as long as you keep it in a dry place. 

Here are some tips on how to store firewood and make it last longer than usual.

1. Store firewood in a dry place.

Keep your firewood in a covered shed or a firewood rack with a cover. Make sure that all the firewood is protected from rain and snow while maintaining adequate airflow on its sides. 

2. Split firewood into quarters.

Another life hack in storing firewood is by splitting them into quarters. This method increases the surface area of the firewood, leaving more of it left out to dry, thereby speeding up the seasoning process.

3. Stack firewood bark-side down. 

We recommend you stack your firewood bark-side down, except the topmost row. 

Stacking your firewood bark side down, except the top side, causes it to dry out quicker. Conversely, with its bark side up, the top row becomes a natural protectant against rain or snow. 

Is it safe to burn old firewood?

It’s safe to burn old firewood if it has no bugs, fungus or mold. However, expect the old firewood to burn too fast and hot. 

If your old firewood has less than 10% moisture content, it can be used for an outdoor fire pit since it kindles quickly. 

Also, avoid burning treated wood because its contaminants will be released into the air upon burning and may infect humans who breathe it.

Is it okay to burn rotting firewood?

You should never burn rotting firewood because it most likely contains fungus and molds that will be released into the air upon burning. 

When you see holes or blue or white mold, you can tell if the firewood is already rotting. 

When these signs are present, there’s a great chance that bugs are also inside it. So don’t burn this rotting firewood if you don’t want these little creatures infesting your home.

A better alternative for this rotting firewood is to use them as compost piles or hugelkultur mounds for raised beds of tomato plants.

FAQs