Cost Per BTU Calculator
Compare the effective energy cost of different fuels (like natural gas, electricity, propane, fuel oil, wood pellets) by calculating their cost per British Thermal Unit (BTU). Lower cost per BTU means more heat energy for your money.
Enter the total cost for a specific quantity of fuel and the total energy content (in BTUs) of that same quantity. Ensure the cost currency and energy units are consistent for comparison.
Enter Fuel Information
Understanding Cost Per BTU & Fuel Comparison
What is BTU?
BTU stands for British Thermal Unit. It's a traditional unit of heat. One BTU is the amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit.
Why Calculate Cost Per BTU?
Different fuels are measured in different units (gallons, therms, kWh, cords, tons). Comparing their cost per unit doesn't tell you which is cheaper for the *same amount of heat energy*. Calculating the cost per BTU standardizes the comparison, showing the true energy cost efficiency.
Cost Per BTU Formula
The formula is straightforward:
Cost Per BTU = Total Cost of Fuel Quantity / Total BTUs in Same Quantity
Ensure your cost and BTU values correspond to the *same* amount of fuel.
Common Fuel Energy Contents (Approximate)
Finding the exact BTU content for your specific fuel depends on quality and source, but here are common approximations:
- Natural Gas: ~100,000 BTUs per therm (A therm is often ~100 cubic feet)
- Electricity: ~3,412 BTUs per kilowatt-hour (kWh)
- Propane: ~91,500 BTUs per gallon
- Fuel Oil (Heating Oil): ~138,700 BTUs per gallon
- Wood Pellets: ~8,000 BTUs per pound or ~16,000,000 BTUs per ton (2000 lbs)
- Cord Wood (Hardwood): ~20,000,000 BTUs per cord (varies widely)
Check your energy bills or contact your supplier for precise values.
Cost Per BTU Examples
Compare the cost per BTU for different fuels (prices are illustrative and vary):
Example 1: Natural Gas
Scenario: Your bill shows you paid $1.20 for 1 therm of natural gas.
1. Known Values: Total Cost = $1.20, Total BTUs = 100,000 (for 1 therm).
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $1.20 / 100,000 BTUs
4. Result: Cost Per BTU = $0.000012 per BTU.
Conclusion: Natural gas costs $0.000012 per BTU in this scenario.
Example 2: Electricity
Scenario: You pay $0.15 per kilowatt-hour (kWh) for electricity.
1. Known Values: Total Cost = $0.15, Total BTUs = 3,412 (for 1 kWh).
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $0.15 / 3,412 BTUs
4. Result: Cost Per BTU ≈ $0.00004396 per BTU.
Conclusion: Electricity costs approximately $0.000044 per BTU in this scenario.
Example 3: Propane
Scenario: You buy a gallon of propane for $2.50.
1. Known Values: Total Cost = $2.50, Total BTUs = 91,500 (for 1 gallon).
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $2.50 / 91,500 BTUs
4. Result: Cost Per BTU ≈ $0.00002732 per BTU.
Conclusion: Propane costs approximately $0.000027 per BTU in this scenario.
Example 4: Fuel Oil (Heating Oil)
Scenario: You purchase heating oil at $3.00 per gallon.
1. Known Values: Total Cost = $3.00, Total BTUs = 138,700 (for 1 gallon).
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $3.00 / 138,700 BTUs
4. Result: Cost Per BTU ≈ $0.00002163 per BTU.
Conclusion: Heating oil costs approximately $0.000022 per BTU in this scenario.
Example 5: Wood Pellets (by Bag)
Scenario: A 40lb bag of wood pellets costs $5.00, and has ~8000 BTU/lb.
1. Known Values: Total Cost = $5.00, Total BTUs = 40 lbs * 8000 BTU/lb = 320,000 BTUs.
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $5.00 / 320,000 BTUs
4. Result: Cost Per BTU ≈ $0.00001563 per BTU.
Conclusion: Wood pellets in this bag cost approximately $0.000016 per BTU.
Example 6: Comparing Natural Gas and Propane
Scenario: Natural gas costs $1.50/therm (100,000 BTU), Propane costs $2.80/gallon (91,500 BTU).
1. NG Calculation: $1.50 / 100,000 BTU ≈ $0.000015 per BTU.
2. Propane Calculation: $2.80 / 91,500 BTU ≈ $0.0000306 per BTU.
3. Comparison: $0.000015 vs $0.0000306.
Conclusion: Natural gas is significantly cheaper per BTU than propane in this specific price comparison.
Example 7: Comparing Electricity and Fuel Oil
Scenario: Electricity costs $0.12/kWh (3,412 BTU), Fuel Oil costs $3.50/gallon (138,700 BTU).
1. Electricity Calculation: $0.12 / 3,412 BTU ≈ $0.00003517 per BTU.
2. Fuel Oil Calculation: $3.50 / 138,700 BTU ≈ $0.00002523 per BTU.
3. Comparison: $0.00003517 vs $0.00002523.
Conclusion: In this scenario, fuel oil is cheaper per BTU than electricity for heating.
Example 8: Natural Gas with Delivery Fee
Scenario: Your natural gas bill is $75 total for 50 therms, including fees.
1. Known Values: Total Cost = $75.00, Total BTUs = 50 therms * 100,000 BTU/therm = 5,000,000 BTUs.
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $75.00 / 5,000,000 BTUs
4. Result: Cost Per BTU = $0.000015 per BTU.
Conclusion: Including delivery fees, the cost is $0.000015 per BTU. Use the *total* cost from your bill for accuracy.
Example 9: Propane (Large Delivery)
Scenario: You get a large delivery of 200 gallons of propane for $400.
1. Known Values: Total Cost = $400.00, Total BTUs = 200 gallons * 91,500 BTU/gallon = 18,300,000 BTUs.
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $400.00 / 18,300,000 BTUs
4. Result: Cost Per BTU ≈ $0.00002186 per BTU.
Conclusion: The cost per BTU for this bulk delivery is lower than the smaller quantity example ($0.000022 vs $0.000027).
Example 10: Wood Pellets (by Ton)
Scenario: A ton (2000 lbs) of wood pellets costs $250.
1. Known Values: Total Cost = $250.00, Total BTUs = 16,000,000 (for 1 ton).
2. Formula: Cost Per BTU = Cost / BTUs
3. Calculation: Cost Per BTU = $250.00 / 16,000,000 BTUs
4. Result: Cost Per BTU = $0.000015625 per BTU.
Conclusion: The cost per BTU for wood pellets by the ton is approximately $0.000016.
Frequently Asked Questions about Cost Per BTU
1. What does "Cost Per BTU" mean?
It's the price you pay for a single British Thermal Unit (BTU) of energy from a specific fuel source. It standardizes the cost across different fuels, regardless of how they are sold (by gallon, therm, kWh, etc.).
2. Why should I calculate Cost Per BTU?
Calculating the cost per BTU is the most accurate way to compare the energy efficiency cost of different heating fuels head-to-head. It helps you determine which fuel provides the most heat for the least amount of money in your location.
3. Is a higher or lower Cost Per BTU better?
A lower Cost Per BTU is better. It means you are paying less money for the same amount of heat energy.
4. How do I find the Total Cost and Total BTUs for my fuel?
Your energy bill is the best source for total cost and the quantity used (gallons, therms, kWh). You'll then need to find the approximate BTU content per unit for that fuel type (e.g., BTUs per gallon of propane). Reliable sources include utility websites, fuel supplier information, or national energy resource sites.
5. Are the BTUs per unit always the same for a fuel type?
Approximate values are widely published, but the exact BTU content can vary slightly based on fuel quality, source, and atmospheric conditions (for natural gas). Using the value provided on your utility bill or by your supplier is most accurate if available.
6. Does this calculator account for heating system efficiency?
No, this calculator determines the cost of the *fuel energy* as it enters your system. The actual cost to heat your space also depends on your heating system's efficiency (how much of the fuel energy is converted into usable heat). A highly efficient system using a fuel with a slightly higher BTU cost might still be cheaper overall than an inefficient system using a fuel with a lower BTU cost.
7. What units should I use for the "Total Cost"?
You can use any currency (USD, EUR, etc.), but be consistent if you're comparing multiple fuels. The resulting "Cost Per BTU" will be in that same currency per BTU.
8. What is a "therm" (for natural gas)?
A therm is a unit of heat energy equal to 100,000 BTUs. Natural gas is often billed in therms or CCF (hundred cubic feet), which is approximately equal to a therm in terms of energy content.
9. What if I use wood or pellets? How do I find the BTUs?
For wood pellets, BTU content is often listed per pound or per ton on the bag or by the supplier. For cord wood, BTU content varies significantly by wood type (hardwood vs. softwood) and moisture content. You'll need to find a reliable estimate for your specific type of wood.
10. Can I use this to compare heating costs for my home?
Yes, by finding the cost per BTU for the different heating fuels available to you (Natural Gas, Propane, Fuel Oil, Electricity, etc.), you can see which one currently offers the most BTUs of energy for each dollar spent.
