Mulberry vs. Hackberry Firewood (BTU Comparison)

At common reference estimates, a standard cord of mulberry contains about 25.8 million BTU, compared with about 21.0 million BTU for hackberry. That puts mulberry roughly 4.8 million BTU, or 23%, ahead per cord. These are estimates, not guaranteed heat outputs: moisture, stacking, species identification, and stove operation all affect usable heat.

The easiest way to make a fair comparison is to start with equal, properly stacked volumes and check the moisture of each species before burning. A pile that looks larger may simply be stacked more loosely, while wood that feels dry may still be too wet inside. Those differences can matter more than the name on a firewood chart.

In my woodlot comparisons, I keep mulberry and hackberry in separate stacks, label them, and test freshly split faces before burning. That gives a more useful answer than relying on drying time or appearance alone. It also helps avoid feeding a stove wet wood, which can waste heat and add smoke and deposits to the chimney.

Mulberry and hackberry BTU comparison

A BTU is a unit of heat energy. A cord is a stacked volume, not a weight: by standard definition it measures 128 cubic feet, arranged as a stack 4 feet high, 4 feet deep, and 8 feet long. The figures below compare estimated energy in that volume.

These estimates are useful for planning, but they are not a promise of heat from every delivered cord. Published charts may use different assumptions about moisture, wood density, and how tightly the cord is stacked. A loosely tossed load does not equal a properly stacked cord, even if the truck bed looks full.

The percentage also needs careful reading: mulberry’s estimate is about 23% higher than hackberry’s. Put another way, hackberry’s reference value is about 19% lower than mulberry’s. The comparison does not mean a stove will produce exactly that difference in a real burn.

Takeaway: If both stacks are dry and measured as equal cords, the common estimates favor mulberry for heat per cord.

What the BTU numbers mean at home

A cord-based heat estimate describes the energy associated with a measured volume of wood. It does not tell you exactly how much heat will reach your rooms. Moisture, fire management, appliance condition, and the way wood is loaded all affect how much useful heat you get.

Moisture content is the amount of water in the wood, shown as a percentage. For firewood, use a suitable moisture meter and aim for 20% or less before burning. Check a freshly split face, not just the outer surface, because the outside can dry sooner than the center.

A “seasoned” label or a set number of months is not a reliable moisture test by itself. Drying time varies with the starting condition of the wood, piece size, weather, and storage. The meter result gives you a direct check on the wood you plan to burn.

Wet wood contains water that must be heated and driven off during burning. That takes energy away from useful room heat and can lead to more smoke and deposits. Do not apply the dry-wood BTU estimates to green or unverified wood. A high chart value cannot make wet fuel a good choice.

A practical comparison should use similar splits, dried to a similar moisture level, and burned in the same appliance under similar conditions. Even then, a short test burn is not a laboratory measurement. For most winter planning, equal-cord estimates and moisture checks are more useful than trying to assign an exact heat output to each load.

Takeaway: Compare the reference values as a starting point, then use moisture readings and equal volumes to judge your actual fuel.

Identify the wood before you stack it

Species identification matters because a BTU chart is only helpful when the wood is named correctly. Mulberry and hackberry are both hardwoods, but bark, leaf, and fruit clues can help distinguish them when those features are present. Since a cut round may lack leaves or fruit, do not rely on one clue alone.

Mulberry trees can have toothed leaves, and some trees bear fruit. Hackberry often has distinctive warty ridges on the bark of mature trunks. Bark varies with age and growing conditions, so it is a clue rather than proof. If identification is uncertain, mark the pile “unknown” instead of assigning it the higher mulberry estimate.

When I sort mixed wood, I label the species and date each stack. That small step prevents a common planning mistake: counting an unknown load as the higher-BTU wood, then expecting it to carry the same heating season. If you can, compare leaves, twigs, bark, and fruit from the same tree. A local extension service or forestry office may help confirm an identification.

Do not compare one loosely piled truckload of mulberry with one tightly stacked cord of hackberry. The volumes are not equal. For a fair cord comparison, stack each species in a consistent way and measure the stack. Keep each species separate so you can also track drying and consumption.

Takeaway: Confirm the tree where possible, label uncertain wood honestly, and compare equal stacked volumes.

Cutting, splitting, and stacking for a fair test

Good processing makes wood easier to dry and makes your comparison more dependable. Split rounds to sizes that fit your appliance and handling needs. Splitting exposes more wood surface to air, but there is no single split size or drying schedule that works for every yard and climate.

Before cutting, wear chainsaw-rated leg protection, a helmet with eye and face protection, hearing protection, gloves, and boots. Check your footing, overhead hazards, escape paths, and the position of other people. Secure the log on stable supports and keep the work area clear.

Use only a bar and chain combination approved for your saw. Bar length, chain pitch, chain gauge, and drive-link count must match the saw and bar. Follow the saw maker’s manual for fuel, starting, operation, and maintenance; do not assume a generic fuel mix or setup applies to your model.

• Check chain tension, sharpness, lubrication, and chain-brake function before cutting.
• Buck logs on stable supports, use controlled cuts, and avoid letting the guide-bar nose contact the wood or ground.
• Split and stack mulberry and hackberry separately.
• Stack wood off the ground, cover the top, and leave the sides open to airflow.
• Measure a freshly split face before burning.

A simple yard comparison can use two labeled stacks with matching split sizes and the same storage conditions. Measure each stack rather than judging by appearance. Later, use the moisture meter on several splits from each pile. This is not a formal heat test, but it removes two major sources of confusion: unequal volume and unequal dryness.

After cutting, shut down the saw as its manual directs. Let it cool before cleaning and inspection. A sharp, correctly maintained chain supports controlled cutting; a worn or mismatched setup is not a shortcut worth taking.

Takeaway: Keep the process consistent from cutting through storage, then compare only after checking moisture.

Which wood should you choose?

Mulberry has the higher reference BTU value per cord, so it is the stronger choice when the goal is more estimated heat from an equal volume of dry wood. Hackberry still provides useful firewood when properly seasoned. The choice in your yard may also depend on which species you have, how much is available, and whether it is ready to burn.

This is where the numbers become useful: they help rank equal volumes, but they do not replace a moisture check. If one species is dry and the other is not, the published per-cord difference is not a fair guide to the immediate burn.

Takeaway: Choose dry, correctly identified fuel first. When both are equally dry and measured, mulberry generally offers more estimated heat per cord.

Frequently asked questions

Does mulberry produce more heat than hackberry?
Common firewood estimates put mulberry at about 25.8 million BTU per cord and hackberry at about 21.0 million. That makes mulberry roughly 23% higher by those reference values.

How many more BTU are in a cord of mulberry?
The difference between the common estimates is about 4.8 million BTU per cord. Treat that as a comparison estimate, not a guaranteed difference in household heat.

Are those BTU figures for a standard cord?
They are commonly reported as estimates per cord. A standard cord is 128 cubic feet of stacked wood, usually arranged as a 4-by-4-by-8-foot stack.

Is hackberry good firewood?
Yes. Hackberry is a hardwood used for firewood when properly dried and burned in an appliance designed for cordwood. The common estimate is lower than mulberry’s, but dry hackberry can still be useful fuel.

What moisture level should I target?
Aim for 20% moisture content or less. Test a freshly split face with a suitable meter rather than relying on bark, sound, or time in storage.

Can I burn wet mulberry because it has a higher BTU rating?
No. A dry-wood chart value does not describe the heat available from wet wood. Wet fuel can waste heat and produce more smoke and deposits.

How do I know if a load is a full cord?
Measure the stacked volume. A standard cord is 128 cubic feet; a loosely tossed load is not the same measurement.

Which wood dries faster?
There is no dependable drying time that applies to every stack. Starting moisture, split size, weather, and storage all affect drying, so check the wood with a meter.

Can I mix mulberry and hackberry in one stack?
You can, but separate stacks make it easier to track species, drying, and volume. If you mix them, do not treat the whole pile as the higher-BTU species.

What is the fairest way to compare the two?
Use equal, properly stacked volumes, confirm the species, and test several freshly split faces from each stack. Keep the wood similarly dry and burn it in the same appliance under similar conditions.

(This article was written by one of our staff writers, Samuel Vance. Visit our Meet the Team page.)