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Sweep's Library: Firewood BTU Comparison Charts

Here are two charts showing the weight and available heat content of one cord of firewood of various species, the first sorted by heat value, and the second sorted alphabetically for easy lookup. The heat value measurement used is the British Thermal Unit, or BTU, which is defined as the amount of thermal energy it takes to raise one pound of water one degree F. One MBTU = one million BTUs.

Weight and Heat content figures are based on seasoned wood at 20% moisture content, and 85 cu ft of wood per cord. A cord of wood is defined as a stack 4 feet high, 4 feet deep and 8 feet long, which comes to 128 cu ft, but we deduct for air space between the pieces in the stack.

To read about how we derived the numbers for our charts, click here.

To view these charts in printable .pdf format, click here.

Regardless of what species of wood you burn, it won't produce optimal heat output and burn time unless it is properly seasoned. You can read more about why you shouldn't burn unseasoned fuel wood here. 

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A Comment from New Zealand:

BTUs? What century was your chart produced? I thought the world measured energy in Joules(J), Kilojoules (KJ), Megajoules (MJ) these days!

I am 70 next birthday, and can distinctly remember learning about energy in high school science classes around 1955~59. We did learn the BTU at first, but the next year we changed to Joules for energy, and were told that the reason was that all science throughout the world was done in metric units, so we better get used to it!

The next few years were an exciting time, as New Zealand changed over to the metric system for everyday use. By this time I was myself a high school teacher and we had the challenge of converting all teaching to metric units. Metric measurement is now universal throughout the country.

OK, I do actually realise you are in the US, and the US has farther to go down this road than any other country in the world. I will just say when the change finally comes your way, embrace it wholeheartedly. It may seem difficult initially, but once you are used to it you will NEVER want to go back to the old system. I have heard literally hundreds of old diehards utter similar sentiments a short time after they have had to change!

Cheers,
Graeme

We might be tempted to convert our firewood rating chart over from MBTUs to MegaJoules, but we have one consideration: how many times have we been sitting at our favorite tavern, glass in hand, and found ourselves engaging in some version of the following exchange?

Bob: "Say, during my last sip I noticed that my pounder of Budweiser has warmed up exactly one degree F while I've been holding it. How much energy did my body have to give up to make that happen?"

Tom: "One BTU."

An easy exchange, no? Now let's try the same conversation in a NZ pub:

Kevin: "Say, during my last sip I noticed that my 0.453592 kg glass of Mac's Gold has warmed up exactly .55555 degrees C while I've been holding it. How much energy did my body have to give up to make that happen?"

Graeme: "1,055 Joules."

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