Compare the cost of heating with butane or using firewood.

The calculation is based on the potential Btu's the firewood species can produce and the heating value of one gallon of butane.

Butane	Lower Heating Value (LHV)		Higher Heating Values (HHV)
Units	British Thermal Units (IT)	Megajoules	British Thermal Units (IT)	Megajoules
gallon	94970	100198.65	103220	108902.87
pound	19466	20537.72	21157	22321.82
gram	42.92	45.28	46.64	49.21
kilogram	42915.18	45277.92	46642.57	49210.51
cubic foot	3023.08	3189.52	3285.70	3466.60
litre	25088.42	26469.68	27267.84	28769.09
cubic metre	106759.23	112636.95	116033.36	122421.67

Butane heating values

Butane lower heating value, one gallon = 94970 Btu
Butane higher heating value, one gallon = 103220 Btu

Calculator uses certain preset values:

• wood dried to 20% moisture content (MC)
• 8084 Btu per pound of wood @ 0% MC
• Propane density = 2213 gr/gal US
• Lower heating value of butane, LHV = 94970 Btu/gal US
• one gallon of butane = 31.4 cubic feet

Example calculation:

• one cord of sugar maple (specific gravity = 0.56 from the list below the calculator) produces 24 million Btu's based on 85 cubic feet of solid wood dried to a 20% moisture content.
• the cost per cord = $280
• one gallon of butane produces 94970 Btu's
• one gallon of propane = $3.45

24000000 ÷ 94970 = 252.7
252.7 * 3.45 = 871.82

To get the equivalent amount of Btu's from heating with firewood, 24 Mbtu's, you have to burn 252.7 gallons of butane at a cost of $871.82

Calculation

1. the volume of firewood in cubic feet
2. the specific gravity of the wood species
3. price of butane per gallon US

Results

1. firewood heat energy in millions of Btu's (Mbtu's)
2. butane in cubic feet to get the equivalent heat value of the firewood
3. the amount of butane in gallons needed to match the firewood Btu's
4. the cost of heating with butane based on price per gal US