What Is White Fir Firewood’s BTU Value? (Cord Heat Specs)
White fir firewood is commonly rated at about 14.6 million BTU per standard cord when seasoned. That is an approximate fuel-energy value, not a promise of heat reaching your room. A cord is 128 cubic feet stacked, and moisture, stacking, and appliance efficiency all affect the useful heat you get.
A quick way to compare firewood is to check two things first: how much wood is in the stack and how dry it is. The label “seasoned” alone does not confirm either one. I use the 14.6-million-BTU figure as a starting point, then adjust expectations for the wood’s moisture and the heating appliance.
Equipment Setup, Firewood Specs & Safety Prep
White fir’s commonly listed heat value is about 14.6 million BTU per cord under seasoned conditions. A cord measures 128 cubic feet of stacked firewood, but it does not contain 128 cubic feet of solid wood. Moisture, piece size, and stacking gaps all affect how much fuel energy a particular stack holds.
What does 14.6 million BTU per cord mean?
A BTU is a unit of heat energy. The 14.6-million figure estimates the energy in a cord of white fir, rather than the amount of heat your home will receive. Think of it as a reference for comparing fuel, not a guaranteed result for every load or stove.
The cord is a volume measure: a stack that measures 4 feet high, 4 feet wide, and 8 feet long equals 128 cubic feet. Since spaces remain between logs, the amount of solid wood inside can vary. Smaller pieces, uneven stacking, and log shape change the gaps. That is why two stacks that look similar may not hold the same amount of wood.
| Measure | White fir reference | What to keep in mind |
|---|---|---|
| Gross heat value | About 14.6 million BTU per cord | Approximate, not a guarantee |
| Standard cord volume | 128 cubic feet stacked | Includes air gaps between pieces |
| Moisture for fair comparison | 20% or less | Check a freshly split face with a suitable meter |
| Example heat delivered at 70% efficiency | About 10.2 million BTU per cord | Depends on the actual appliance and how it is used |
Why moisture changes the comparison
Moisture content tells you how much water is in the wood. Wet wood uses some of its energy to heat and drive off that water, leaving less useful heat for the room. It can also produce more smoke and contribute to creosote buildup in a chimney or flue.
For a fair comparison, aim to measure 20% moisture content or less. Split a piece and test the freshly exposed inner face with a suitable moisture meter. Follow the meter’s instructions, including any species setting it provides. Bark, color, cracks, and weight can offer clues, but they do not reliably confirm the moisture reading inside a log.
Estimate useful heat, not just fuel energy
To estimate delivered heat, multiply the gross cord value by the appliance’s efficiency. At an assumed 70% efficiency, the calculation is 14.6 million BTU × 0.70, or about 10.2 million BTU delivered per cord.
| Assumed appliance efficiency | Calculation | Approximate delivered heat |
|---|---|---|
| 60% | 14.6 million × 0.60 | 8.8 million BTU |
| 70% | 14.6 million × 0.70 | 10.2 million BTU |
| 80% | 14.6 million × 0.80 | 11.7 million BTU |
These are comparison scenarios, not a rating for a specific stove. Real output depends on the appliance, its condition, draft, loading, and operating practice. Use the efficiency listed for your appliance when available, and treat estimates as approximate.
A firewood BTU rating also does not tell you which chainsaw bar or chain to use. Match the bar, chain pitch, chain gauge, and drive-link count to the saw maker’s specifications and the wood you are cutting. The BTU value describes fuel energy; it is not a machine-compatibility measurement.
Field Cutting, Seasoning & Heating Operation
Getting close to the reference value starts with safe cutting, suitable pieces, and adequate drying. Cut logs to the length your appliance allows, split larger rounds, and stack wood so air can move around it. Then verify dryness at a freshly split surface instead of relying on appearance alone.
Step 1: Prepare the cutting area
Wear task-appropriate chainsaw protective gear and check the saw before cutting. Inspect the chain brake, chain tension, and general saw condition according to the owner’s manual. Choose a stable work area, secure the log, and keep bystanders clear.
Plan each cut so the bar is less likely to pinch and the chain will not strike the ground. Logs can hold both compression and tension, which may close the cut or shift the wood as you work. If a cut begins to bind, do not force the saw. Stop and address the support or cutting position safely.
Step 2: Buck and split to fit the appliance
“Bucking” means cutting a log into shorter sections. Use the firebox length specified for your stove or other appliance. Split larger rounds to expose more of the wood’s interior to moving air; this can help the pieces dry. The right piece size also makes it easier to load the appliance as directed.
Keep the saw within the limits in its manual, and use safe cutting technique. A firewood heat estimate cannot tell you how to fell a tree or make a risky cut. For felling or other high-consequence tree work, get suitable training and follow applicable safety requirements.
Step 3: Stack and verify dryness
Stack wood off the soil so air can move beneath and around it. Cover the top to shed rain, but leave the sides open to airflow. Drying time varies with conditions, so do not assume a fixed number of weeks or months will make every stack ready.
When checking a piece, split it and measure the newly exposed face. A reading of 20% or less gives a useful basis for comparing it with the seasoned-wood reference. Follow the meter directions; a reading taken through bark or from an old outer surface may not represent the center.
Step 4: Burn and compare heat
Use dry wood in an approved appliance and follow its operating instructions. If you want a rough delivered-heat estimate, multiply the gross BTU figure by the appliance’s actual efficiency when known. For example, a 70% estimate gives about 10.2 million BTU from a cord rated at 14.6 million gross BTU.
Worked cord-heat scenarios
These examples show how the same reference value can support different decisions. They are calculations, not reports from specific homes or tests of particular stoves.
- Comparing a supplier’s quote: Confirm that the amount is a full cord, not a smaller stack, and ask how the wood was measured. Then check moisture at a freshly split face.
- Estimating a heating season: Use the approximate 14.6-million-BTU gross value, then apply a realistic appliance-efficiency figure. The result is an estimate of delivered heat, not a guarantee of room temperature or burn time.
- Comparing a damp load with seasoned wood: Do not treat the damp load as equal to the seasoned reference. Its useful heat will be lower, and a meter reading is a better guide than the label or appearance.
Maintenance, Cutting Hazards & Sharpening
A binding or poorly maintained saw can make firewood work more dangerous. A pinched guide bar can stop the chain abruptly and may contribute to loss of control or kickback. Keep the chain sharp and correctly tensioned, and rely on the saw maker’s specifications rather than the wood’s BTU rating.
Prevent binding and keep the saw in good condition
Support logs so the cut stays open. Think ahead about which side is under compression and which side is under tension; the wrong cut order can trap the bar. If the bar binds, do not push harder or try to force the chain through. Stop and use a safe method to release the pressure.
A dull chain takes more effort to cut, which can tempt an operator to push harder. Check and adjust tension as the saw manual directs. Use the specified chain, bar, and sharpening angles. There is no universal bar length, chain pitch, gauge, drive-link count, or sharpening angle that follows from white fir’s heat value.
For tree felling or other work where a mistake could cause serious injury, seek proper training and follow local safety rules. A firewood BTU estimate is not a guide to cutting technique.
Storage, Seasonal Care & Negative Scope
Store seasoned firewood off the ground with a rain-shedding cover over the top and open sides for airflow. Keep the stack clear of buildings as local fire, pest, and code guidance requires. Store and maintain the chainsaw according to its maker’s instructions, and do not treat a BTU table as proof that wood is dry.
What the reference value cannot tell you
The 14.6-million-BTU figure is not exact for every white fir cord. Species identification, moisture, piece size, and stacking volume can all vary. A stack that is smaller than a full cord should not be compared as if it contains a full cord, and an unspecified “dry” value is not directly comparable to a measured load.
Do not burn wood that is visibly wet or has not been checked as though it were seasoned. Excess moisture reduces useful heat and can increase smoke and creosote accumulation. Follow the appliance maker’s guidance for fuel and operation.
Bottom line: Use about 14.6 million BTU per seasoned cord as a gross-energy reference. For a practical comparison, confirm a full 128-cubic-foot stacked cord, measure moisture on a freshly split face, and account for your appliance’s efficiency.
Quick answers
How many BTUs are in a cord of white fir?
White fir is commonly listed at about 14.6 million BTU per cord when seasoned. The figure is approximate and can vary with moisture, identification, and how the cord is stacked.
How much heat does a cord deliver to a room?
It depends on the appliance. At an assumed 70% efficiency, 14.6 million gross BTU works out to about 10.2 million delivered BTU. Actual output may differ.
What size is a standard cord of firewood?
A standard cord is 128 cubic feet of stacked wood, often described as a 4-by-4-by-8-foot stack. The volume includes spaces between pieces.
What moisture level should white fir firewood reach?
For a fair comparison with seasoned firewood, use 20% moisture content or less. Measure a freshly split face with a suitable meter and follow its instructions.
Can I tell if white fir is dry by looking at it?
Appearance can provide clues, but it cannot confirm the moisture inside a piece. Use a meter on a newly split surface for a more useful check.
Does a wet cord still have 14.6 million BTU?
Do not treat the seasoned reference as an exact value for wet wood. Water in the wood reduces useful heat, so verify moisture before comparing loads.
Does white fir’s BTU value determine chainsaw size?
No. Choose the bar and chain to match the saw maker’s specifications and the wood diameter. BTUs measure fuel energy, not chainsaw compatibility.
How should I stack white fir while it dries?
Keep it off the ground, cover the top to shed rain, and leave the sides open for airflow. Follow local guidance on where to store firewood.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
