What Is Crepe Myrtle Firewood BTU? (Heat Output)
Well-seasoned crepe myrtle firewood is estimated to contain about 25–26 million BTU per standard cord. Treat that as an approximate heat-content figure, not a guaranteed amount of warmth: moisture, stacking, wood size, and appliance performance all matter. A standard cord is 128 cubic feet of neatly stacked wood, including the air spaces between pieces.
A BTU is a unit of heat, not a promise that all the heat will reach your room. Think of the cord estimate as a way to compare the fuel’s potential energy, provided the wood is measured and seasoned in a fair, consistent way. A damp, loosely piled load can make the number look more useful than it is.
How much heat does crepe myrtle firewood contain?
Crepe myrtle (Lagerstroemia spp.) has an estimated heat content of about 25–26 million BTU per cord when well seasoned. That figure describes the wood’s potential energy under an assumed condition. It does not guarantee a stove’s heat output, because the delivered warmth also depends on moisture, appliance, and operation.
The estimate is best used as a planning figure. It can help you judge whether a properly measured supply may suit your heating needs, but it cannot tell you exactly how long the wood will burn or how warm a room will become.
BTU ratings may refer to energy in the fuel or heat delivered by an appliance. Those are not the same measurement. Some of the fuel’s energy goes up the flue, and a fire that is not burning as intended may deliver less useful heat.
For a fair estimate, the wood needs to be seasoned, measured as a true cord, and compared on the same basis as any other firewood. A pile’s size or the number of logs alone is not enough to establish its heat content.
What does 25–26 million BTU per cord mean?
A cord is a stacked volume of 128 cubic feet, including the gaps between pieces. The heat estimate applies to that volume, not to 128 cubic feet of solid wood. A loose pile, pickup load, or neatly stacked row with unknown dimensions cannot be called a cord just by looking at it.
The 25–26 million BTU estimate is approximate because real firewood varies. Moisture, piece size, stacking, and the exact wood being measured can all affect how much usable heat you get. Treat the number as a guide, not a species guarantee.
| Measurement | What it means | Why it matters |
|---|---|---|
| Standard cord | 128 cubic feet of stacked wood, including air spaces | Sets the volume basis for the estimate |
| Estimated crepe myrtle heat | About 25–26 million BTU per well-seasoned cord | A planning estimate, not guaranteed output |
| Oven-dry heat by weight | Roughly 8,000–8,600 BTU per pound | A dry-wood reference, not the as-burned value |
| Firewood moisture target | About 20% or less on a freshly split face | Helps assess whether wood is ready to burn |
A comparison between firewood types only makes sense if both amounts are measured as equivalent cords and seasoned to a similar moisture level. Otherwise, a difference may come from how the wood was stacked or dried, rather than from the species.
How moisture changes crepe myrtle’s heat output
Moisture content is the water held in the wood. As-fired heat per pound falls as moisture rises, because some of the available energy is used to heat and evaporate that water instead of warming your home. A dry-weight BTU value therefore should not be treated as the heat from a pound of damp firewood.
Crepe myrtle’s estimated cord figure assumes well-seasoned wood. For a practical check, aim for a moisture-meter reading of about 20% or less. Split a piece and place the meter’s pins on the newly exposed face, following the meter maker’s instructions. The outside of a log may be drier than its center, so an outside-surface reading can mislead.
Drying time varies with conditions, so the number of months in a stack does not prove that the wood is ready. Airflow, rain exposure, piece size, and local weather all affect drying. Measure the wood instead of relying on a calendar.
Burning wet or green wood does not deliver the seasoned-wood estimate. Excess water reduces usable heat and can increase smoke and creosote. If the meter reading is above your target, continue seasoning the wood rather than assuming the cord will perform like dry fuel.
What the estimate looks like in practical situations
These examples show how to use the estimate without claiming a precise result for a particular stove or home. They are planning scenarios, not measured case studies: the heat a household receives depends on the actual cord volume, moisture, and heating appliance.
| Situation | What you can reasonably conclude |
|---|---|
| A measured, stacked cord reads about 20% moisture or less on split faces | The 25–26 million BTU estimate is a useful rough reference |
| A loose pile is described as “about a cord” | You do not yet know whether it contains a full cord |
| The wood is wet, green, or untested | Do not apply the seasoned-wood estimate as expected heat |
| A stove burns the wood but the room’s heat varies | The cord estimate alone cannot identify the cause or predict delivered heat |
For example, if you have a measured stack that is verified as one cord and the wood meets the moisture target, you can use the estimate to plan fuel supply. You still cannot assume that your appliance will deliver all 25–26 million BTU into the living space.
By contrast, if a seller describes a loosely stacked load as a cord, first check its stacked dimensions. If the wood is also damp, both volume and moisture differ from the estimate’s assumptions. Those are two reasons not to use the headline number as a promise.
Cutting crepe myrtle safely for firewood
The tree species does not determine chainsaw setup. Use a saw suited to the wood’s diameter, and follow the saw manufacturer’s directions for bar length, chain pitch and gauge, fuel mix, engine speed, or battery use. There is no universal bar or chain specification for crepe myrtle.
Before cutting:
- Wear suitable chainsaw personal protective equipment (PPE), and inspect the chain brake, chain tension, bar, and controls.
- Check the fuel and oil system, or the battery and its condition, as directed in the manual.
- Clear the work area and choose a stable position before starting.
- Follow applicable workplace rules, including OSHA logging requirements where they apply.
Buck only stable wood, and keep the guide-bar nose away from contact with the stem or nearby objects. Kickback can happen when the upper part of the guide-bar nose touches wood; the saw may rotate abruptly toward the operator. Keep a firm grip and do not cut above shoulder height.
Large or tensioned stems can move as they are cut. Use a competent operator and a planned cutting sequence; do not improvise felling or release cuts. If you are unsure how a stem is supported or loaded, stop and get qualified help.
Season, measure, and store the wood
Seasoning means drying cut wood so it burns more effectively. Split rounds to the size your appliance accepts, then stack them off the ground with room for airflow. Cover the top to limit rain while leaving the sides open so air can move through the stack.
Check moisture on a freshly split face with a moisture meter. Take readings from several pieces rather than assuming one log represents the whole stack. Follow the meter instructions for use and any species settings; the goal is a reading around 20% or less.
Store firewood and equipment as their manufacturers direct. Keep the wood protected from rain but ventilated, and do not treat a covered, tightly sealed pile as a substitute for drying airflow. If moisture readings remain high, give the wood more time and check again before using the seasoned-cord heat estimate.
After cutting, shut down the saw, let it cool, and clean and inspect it. Check the chain and bar and follow the maintenance steps in the manual. A well-maintained saw is important for safe cutting, but maintenance does not change the wood’s BTU rating.
How to use the BTU estimate when planning
Use 25–26 million BTU per cord as an approximate fuel-energy reference for well-seasoned crepe myrtle, not as a precise prediction of household heat. Start by confirming the amount is a stacked 128-cubic-foot cord. Then verify that the wood is dry enough and that your appliance is approved for solid fuel and operated according to its instructions.
I would keep the assumptions beside any estimate: cord volume, moisture reading, and the appliance being used. That makes the number easier to interpret and prevents a loose pile or damp wood from being mistaken for the conditions behind the estimate.
The practical takeaway is simple: measure the stack, test split faces, and treat the BTU figure as approximate. Those checks matter more than a confident-sounding number without its measurement basis.
Frequently asked questions
How many BTUs are in a cord of crepe myrtle?
A well-seasoned standard cord is estimated at about 25–26 million BTU. This is an approximate heat-content figure, not a guaranteed amount delivered by a stove.
Is crepe myrtle good firewood?
Its estimated heat content makes it a potential firewood option when properly seasoned. Its actual usefulness depends on the wood’s moisture, the amount available, and whether your appliance is approved for solid fuel.
Does crepe myrtle produce 25–26 million BTU when it is green?
No. That estimate is for well-seasoned wood. Green or wet wood has less usable heat per pound because energy is spent evaporating water.
What moisture reading should I look for?
Aim for about 20% moisture or less. Measure a freshly split face with a moisture meter and follow the meter maker’s instructions.
What counts as one cord of firewood?
A standard cord is 128 cubic feet of neatly stacked wood, including air spaces. A loose pile or unstacked load is not automatically a cord.
How many BTUs are in a pound of crepe myrtle?
Oven-dry wood is roughly 8,000–8,600 BTU per pound. As-fired heat per pound falls as moisture rises, so this dry-weight range does not describe damp firewood.
Can I compare crepe myrtle with another firewood species by cord?
Only if both amounts are measured as equivalent stacked cords and have similar seasoning and moisture conditions. Otherwise, volume and water content can distort the comparison.
Does the BTU rating tell me how much heat my room will get?
No. It estimates fuel heat content. Appliance efficiency, operation, and the condition of the wood affect how much heat reaches the room.
Does crepe myrtle need a special chainsaw bar or chain?
No species-specific bar or chain size can be assumed. Use a saw that suits the wood diameter and follow the saw manufacturer’s specifications.
How can I tell whether the wood is dry enough?
Split a piece and test the newly exposed face with a moisture meter. Do not rely only on the outside surface or on how long the wood has been stacked.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
