# Amount of Heat(Btu's) from A Cord of Firewood

One pound of wood is one pound of wood. The density of wood, pounds per cubic foot, will be different, depending on the species you are using as fire wood. Density of wood will vary at different moisture contents and unless you know at which moisture content it was determined it is kind of useless. To be able to calculate the density you would need to know the basic specific gravity of the wood species. The specific gravity where the wood is at its lightest weight, as in, oven dried to where it contains 0% moisture.

#### Calculating Weight @ 0% MC

The formula to calculate the weight at 0% moisture:volume(cubic feet) x Specific Gravity(Basic) x weight of one cubic foot of water = weight in lbs

Easy to Google what the basic specific gravity of a certain species is.

One source lists Eastern Hemlock as having a basic specific gravity of 0.41

If you consider that on average one cord of wood (128 Cubic Ft ) contains a volume of 85 cubic feet of solid wood.

The weight of one cubic foot of water = 62.4 lbs

What one pound of dry wood (0%MC) can produce = 8600 Btu's

Then the weight of one cord of Eastern Hemlock @ 0% MC would be:

85 * 0.41 * 62.4 = 2174.64 lbs

Since this is all dry wood then this cord could potentially produce:

2174.64 * 8600Btu/lb = 18696400 Btu's 18.7 million Btu's

#### Calculating Weight @ Various % MC

To calculate the weight of this cord @ various MC% you will have to add to the first formula:(1 + MC/100)

and it becomes:

volume(c f) x Specific Gravity(B) x 62.4 *(1 + MC/100)

Since most likely the firewood you are burning will contain approx 20% of moisture after being air dried:

One cord of Eastern Hemlock @ 20% MC:

85 * 0.41 * 62.4*(1 + 20/100) =

85 * 0.41 * 62.4 * 1.2 = 2609.568 lbs

So now you are thinking more pound weight per cord = more Btu's!! Let's make it heavier by adding more water!!

If you read how to calculate Btu's per pound of dried wood then you would know that the dried wood is the part that produces Btu's and not the additional moisture in the wood.

**Proportional Weight of Wood and Water in One Pound**

At 20% MC one pound of wood will contain 0.83 lb of dry wood and 0.17 lb of water

8600 * 0.83 = 7138 Btu's @ 20% MC

2609.85 * 7138 = 18629109.3 Btu's = 18.6 MBtu's. That is close to the same as the previous result @ 0 MC of 18696400 Btu's = 18.7 MBtu's

#### Firewood Calculators

##### Firewood

Cords of Firewood CalculatorFirewood Cost Calculator

Cords of Firewood Calculator with Packing Percentage

Firewood Cost Calculator

Firewood Cords Calculated in Metres

##### Btu's in relation to Firewood

Calculating potential Btu's of your FirewoodBtu's per Cubic Metre of "Stacked" Firewood

"Simple" Btu's per Cord of Firewood - Imperial

Btu's per Cubic Metre of "Stacked" Firewood

Btu's One Pound of Wood Could Produce

Calorific Value of Wood Calculator

Firewood Caloric Value in Mega Joules

##### Moisture Content

Proportional Weight of Wood and Water in One PoundMoisture Content Measured On A Dry Basis

Moisture Content Measured On A Wet Basis

Moisture Content Calculator

##### Energy

Convert Btu/Pound to Btu/Kilogram and Btu/Kilogram to Btu/Pound##### Information

Amount of Heat(Btu's) from A Cord of FirewoodBtu's of Wood at Various MC