What Is Hemlock Firewood’s BTU Rating? (BTU Output Chart)

Hemlock firewood offers an estimated 15.9 million BTU per full cord for eastern hemlock and 17.1 million for western hemlock. These are reference figures, not guarantees. The wood’s species, how tightly it is stacked, and its moisture level all affect useful heat. For a fair comparison, compare properly measured cords at similar moisture levels.

If you found “BTU per cord” in a firewood chart, the short answer is that hemlock is a moderate-to-lower heat-density choice compared with many dense hardwoods. It can still be useful firewood, especially when it is dry and available locally. The key is to know which hemlock you have and how much wood you are actually buying.

BTU means British thermal unit, a measure of heat energy. A cord’s BTU rating estimates the energy in a measured stack; it does not promise how much warmth a particular stove or home will get. Here’s how to read the numbers and judge a load without getting tripped up by the jargon.

Hemlock BTU Rating, Cord Basis, and Moisture

The figures below are approximate heat estimates for air-dried hemlock. They help compare the two species, but should not be treated as guaranteed output. The amount of useful heat depends in part on moisture and on whether the load is a true, neatly stacked cord.

A full cord is a stacked volume of 128 cubic feet, often arranged in a stack about 4 feet high, 4 feet deep, and 8 feet long. The wood must be stacked, not loosely thrown into a pile. Gaps between pieces mean the measured stack contains less wood.

A face cord is a stack with a face of 4 by 8 feet, but its depth depends on the length of the pieces. For that reason, a face cord is not automatically one-third of a full cord. Ask for the log length and stacked dimensions before comparing a seller’s price or heat estimate.

Why moisture changes the comparison

Moisture content is the amount of water in the wood, shown as a percentage. Water in a log takes heat to drive off during burning, so wet wood gives less useful heat and tends to make more smoke. It can also raise creosote risk in a chimney.

For a practical check, aim for 20% moisture content or less. Split a piece, then press a moisture meter’s pins into the newly exposed face. Testing only the outside can give a misleading reading because the surface may be drier than the inside.

Published firewood charts may use different assumptions about species, stacking, and moisture. So, treat 15.9 and 17.1 million BTU as reference estimates, not precise promises. When I compare two loads, I first check whether both are full cords and at a similar moisture level. Otherwise, the numbers may not be a fair comparison.

What the numbers mean for heating

Hemlock’s estimates place it in a moderate-to-lower heat-density range compared with many dense hardwoods. That does not make it unusable. Dry hemlock can burn readily, and the best choice also depends on local supply, price, storage space, and how often you want to reload your stove.

Hemlock is resinous, but resin does not mean more heat per cord. Resin can help dry wood catch and burn readily; it does not change the basic cord-volume comparison. For planning, use the species figure as a rough estimate, then give more weight to dry wood, correct measurement, and safe operation of the appliance.

These scenarios do not adjust the BTU figure mathematically for wet wood. They show why a chart alone cannot predict the heat you will get from a particular purchase.

Chainsaw Setup and Site-Safety Preparation

If you are cutting your own hemlock, the saw setup is a separate safety issue from the wood’s BTU rating. There is no universal bar-and-chain combination for hemlock. Use only a bar and chain approved for your exact saw, and follow its manual for fuel, starting, cutting, and maintenance.

Before starting, wear chainsaw-rated leg protection, a helmet, eye and hearing protection, gloves, and sturdy boots. Clear the work area of bystanders and obstacles. Check for overhead hazards, make sure your footing is stable, and plan an escape route before cutting.

Inspect the saw as its manual directs. Check the chain brake, throttle lockout, chain tension, guide bar, and chain catcher. The chain must match the saw and installed sprocket, including its pitch, gauge, and drive-link count. Do not choose a bar just because it seems suitable for the size of the log.

Use the fuel mix ratio and idle and maximum engine speeds specified by the manufacturer. These settings vary by model. A generic ratio or tuning by sound alone can damage the saw or make it unsafe to use.

Start the saw using the manufacturer’s cold- or warm-start steps, on stable ground. Before each cut, assess the log for lean, compression, and bind. These describe how the wood may shift or pinch the bar as it is cut. Plan the cut and escape direction first; use wedges where appropriate.

One hazard deserves special care: contact with the upper quadrant of the guide-bar nose can cause rotational kickback, which can throw the bar rapidly toward you. Keep that area clear, hold the saw firmly with both hands, and avoid cutting with the bar tip. If you are unsure how a log will move, stop and get help from a qualified saw user rather than guessing.

Field Cutting, Bucking, and Firewood Processing

Bucking means cutting a log into shorter pieces. For firewood, the goal is to make manageable rounds without trapping the saw or putting yourself in the path of a moving log. Log size, support, and tension matter more to safe cutting than the tree’s BTU rating.

Use a sharp, correctly tensioned chain and controlled cuts. Position logs so they are supported and less likely to roll or close on the bar. Think through where the cut will finish before you begin, and do not reach or cut from an unstable stance.

A pinched bar can be difficult to free and may create a sudden movement. Look for compression or tension in the log before cutting, and use wedges when suitable. If the saw binds, do not force it or rev it in place. Stop, secure the situation, and follow the manual or seek experienced help.

Split the rounds to a size that suits your storage and appliance instructions. Splitting exposes more wood surface to air, which supports drying. Stack the pieces with airflow around them and keep them protected from rain and ground moisture. Recheck a freshly split face with a moisture meter before relying on the 20% target.

The BTU chart applies to a full cord, not to every pile that looks similar in size. A loosely stacked load has more empty space than a well-stacked cord. When buying processed wood, confirm the stacked dimensions and piece length, then compare moisture readings on split faces.

Sharpening, Maintenance, and Seasonal Storage

A sharp chain and a well-maintained saw help you make controlled cuts, but upkeep must follow the saw’s instructions. After cutting, engage the chain brake and shut off the engine. Let the saw cool before cleaning or checking it.

Clean the cooling fins, sprocket cover, and air filter as specified in the manual. Check chain tension and bar oil before storage, and inspect the chain and bar for wear. Use the correct bar oil and chain parts for the saw; do not assume parts fit because they look close.

Before storing the saw, follow the maker’s instructions for fuel and storage. Keep it in a secure, dry place, away from children. Store firewood separately in a dry, ventilated stack so it can continue seasoning and does not block access to the saw or work area.

For the firewood itself, note the species, stack size, and moisture reading. This record makes it easier to compare one load with another and see whether seasoning has improved the wood’s condition. The practical takeaway is simple: the BTU estimate helps with planning, while correct measurement and dry wood help make the estimate more useful.

Hemlock Firewood BTU FAQs

These quick answers cover the main points behind hemlock’s heat rating. The figures are estimates per full cord, and the fairest comparisons use the same cord basis and similar moisture levels.

How many BTUs are in a cord of hemlock?

Eastern hemlock is estimated at about 15.9 million BTU per full cord. Western hemlock is estimated at about 17.1 million BTU per full cord. Treat both as approximate chart values.

Which hemlock has the higher BTU rating?

The reference estimate for western hemlock is higher: about 17.1 million BTU per cord, compared with about 15.9 million for eastern hemlock. Actual fuel performance can vary.

Is hemlock good firewood?

Hemlock can be useful firewood when it is properly seasoned and suitable for your appliance. It is generally a moderate-to-lower heat-density choice compared with many dense hardwoods, so consider local price and supply as well as its rating.

Does resin make hemlock produce more heat?

No. Resinous wood may burn readily when dry, but that does not mean it provides more heat per cord. Use the species and cord estimates as a rough comparison.

What moisture level should hemlock firewood reach?

Aim for 20% moisture content or less. Test the freshly split face with a moisture meter, since the outside of a piece may be drier than its center.

How large is a full cord of firewood?

A full cord is 128 cubic feet of stacked wood. A common stack measures about 4 feet high, 4 feet deep, and 8 feet long.

Is a face cord one-third of a cord?

Not necessarily. A face cord is often 4 feet high and 8 feet long, but its depth depends on the length of the pieces. Ask for the actual dimensions before comparing it with a full cord.

Why might my hemlock not match the chart’s heat output?

The chart gives an estimate, not a guarantee. Species identification, moisture, and how much wood is actually stacked in the measured volume can all affect the comparison.

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