Natural Gas vs Propane Cost Calculator
Compare the operational cost of appliances using Natural Gas versus Propane based on price, energy content, and appliance efficiency.
Enter the cost of one therm of natural gas. A therm is 100,000 BTUs.
Please enter a valid price.
Enter the cost of one gallon of liquid propane.
Please enter a valid price.
Enter the BTU per hour rating of the appliance (e.g., a furnace). Common furnace ratings are 80,000-150,000 BTU/hr.
Please enter a valid BTU rating.
Enter the Annual Fuel Utilization Efficiency (AFUE). Modern furnaces are typically 80% to 98%.
Please enter a valid efficiency rating (1-100).
Enter the estimated number of hours the appliance runs per month.
Please enter a valid number of hours.
Natural Gas Cost
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Propane Cost
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Monthly Cost Comparison
What is a Natural Gas vs Propane Cost Calculator?
A natural gas vs propane cost calculator is a specialized tool designed to provide a clear financial comparison between two common heating fuels. While both are effective, they are sold in different units (therms for natural gas, gallons for propane) and contain different amounts of energy. This calculator bridges that gap by converting everything to a common denominator—the cost to produce a certain amount of heat—allowing homeowners and businesses to make an informed decision based on local prices and appliance efficiency. It answers the crucial question: for the same amount of heat, which fuel will cost less?
The Formula for Comparing Fuel Costs
To accurately compare natural gas and propane, we must determine the cost per unit of energy (like a million BTUs) and then factor in appliance usage. The core of the natural gas vs propane cost calculator lies in this formula:
Monthly Cost = (Appliance BTU Rating / (Fuel Energy Content per Unit * Appliance Efficiency)) * Price per Unit * Hours of Use
This formula first calculates how many units of fuel are needed to produce the required heat output, then multiplies that by the price per unit and the duration of use.
Key Variables Table
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Fuel Price | The market cost of the fuel. | $/therm (Gas), $/gallon (Propane) | $0.50 – $3.00 (Gas), $1.50 – $5.00 (Propane) |
| Energy Content | The amount of heat stored in a unit of fuel. | BTU/therm or BTU/gallon | ~100,000 (Gas), ~91,500 (Propane) |
| Appliance BTU Rating | The appliance’s hourly heat input. | BTU/hour | 75,000 – 150,000 for a furnace |
| Appliance Efficiency | The percentage of fuel converted to usable heat (AFUE). | Percentage (%) | 80% – 98.5% |
| Hours of Use | The total time the appliance operates. | Hours/Month | 50 – 500+, depending on climate |
Practical Examples
Example 1: High-Efficiency Furnace in a Cold Climate
A homeowner is considering a new 100,000 BTU/hr furnace with 96% AFUE. They estimate it will run for 250 hours a month in winter. Natural gas costs $1.10/therm and propane costs $2.80/gallon.
- Inputs: Gas Price: $1.10, Propane Price: $2.80, BTU: 100,000, Efficiency: 96%, Hours: 250
- Natural Gas Monthly Cost: Approximately $286.46
- Propane Monthly Cost: Approximately $764.12
- Result: Natural gas offers substantial savings. For more on efficiency, see our appliance energy usage guide.
Example 2: Standard Efficiency Water Heater
Let’s calculate the cost for a 40,000 BTU/hr water heater with 80% AFUE, running for 90 hours per month. Natural gas is $1.80/therm and propane is $3.50/gallon.
- Inputs: Gas Price: $1.80, Propane Price: $3.50, BTU: 40,000, Efficiency: 80%, Hours: 90
- Natural Gas Monthly Cost: Approximately $81.00
- Propane Monthly Cost: Approximately $172.68
- Result: Even with a less efficient appliance, natural gas is more economical in this scenario. You can explore more with our BTU calculator.
How to Use This Natural Gas vs Propane Cost Calculator
- Enter Fuel Prices: Input your local cost for natural gas in dollars per therm and propane in dollars per gallon. These are found on your utility bills.
- Input Appliance Details: Enter the appliance’s BTU/hour rating and its AFUE efficiency percentage. This info is typically on the appliance’s label.
- Estimate Usage: Provide the number of hours you expect the appliance to run each month.
- Calculate and Analyze: Click “Calculate”. The tool will display the monthly cost for each fuel, highlight the cheaper option, and show the savings. The bar chart provides a quick visual comparison.
Key Factors That Affect the Cost Comparison
- Market Fuel Prices: This is the most volatile factor. Natural gas prices are often more stable than propane, which can fluctuate significantly with seasonal demand and oil prices.
- Appliance Efficiency (AFUE): A higher AFUE rating means less fuel is wasted. A 95% AFUE furnace saves much more than an 80% model over its lifetime, magnifying the impact of fuel price differences.
- Geographic Location: Proximity to natural gas mains is critical. If a pipeline isn’t available, propane is the only option, making the cost comparison moot. Rural areas rely more heavily on propane.
- Energy Content (BTU): Natural gas (per therm) and propane (per gallon) have different energy densities. Our natural gas vs propane cost calculator normalizes this difference.
- Climate and Home Insulation: Colder climates mean more usage hours, amplifying the cost difference. Poor insulation forces any heating system to work harder, increasing consumption for either fuel. Consider an energy audit to find improvements.
- Installation and Tank Costs: Switching to natural gas may involve costs to run a new line, while propane requires a storage tank (rented or owned). These upfront costs should be considered alongside the long-term running costs.
Frequently Asked Questions (FAQ)
- 1. Which is generally cheaper, natural gas or propane?
- In most regions with access to a pipeline, natural gas is significantly cheaper per unit of energy than propane. This is why it’s the preferred fuel for heating in most suburban and urban areas.
- 2. What is a BTU?
- A British Thermal Unit (BTU) is the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit. It’s the standard unit for comparing the energy content of different fuels.
- 3. How many BTUs are in a therm of natural gas vs a gallon of propane?
- A therm of natural gas contains approximately 100,000 BTUs. A gallon of propane contains about 91,500 BTUs. This near-equivalence in energy makes a direct price comparison tricky without a calculator.
- 4. What does AFUE mean?
- AFUE stands for Annual Fuel Utilization Efficiency. It’s a percentage that measures how much fuel a furnace converts into usable heat over a season. An AFUE of 95% means 95% of the fuel becomes heat, and 5% is lost.
- 5. Can I convert my propane appliance to natural gas?
- Often, yes. Many furnaces, water heaters, and stoves can be converted from propane to natural gas (or vice versa) using a conversion kit. This should always be done by a qualified HVAC professional.
- 6. Why would someone choose propane if natural gas is cheaper?
- The primary reason is lack of access. Natural gas requires a physical pipeline to the home. In rural areas where pipelines are not available, propane (which is delivered by truck and stored in a tank) is a common and effective alternative to electricity or oil heat.
- 7. Does appliance efficiency matter more than fuel price?
- Both are critical. A cheap fuel used in an inefficient appliance can still be expensive. Conversely, an expensive fuel in a hyper-efficient appliance might be competitive. Use the natural gas vs propane cost calculator to see how they interact. Learn about high-efficiency systems to understand more.
- 8. What’s a typical BTU rating for a home furnace?
- For an average-sized home in a moderate climate, a furnace might be rated between 80,000 and 120,000 BTU/hr. Larger homes or those in very cold climates may require 150,000 BTUs or more.
Related Tools and Internal Resources
Explore these resources to make more informed energy decisions for your home.
- BTU Calculator: Understand and calculate the heating or cooling needs for any room size.
- Appliance Energy Usage Guide: Estimate the electricity consumption and cost of various household appliances.
- Home Energy Audit Checklist: A step-by-step guide to identifying energy loss in your home.
- Insulation ROI Calculator: Determine the payback period and long-term savings from upgrading your home’s insulation.
- Solar Panel Cost Estimator: Get a rough estimate of the cost and benefits of installing solar panels.
- Guide to High-Efficiency HVAC Systems: Learn about the latest in heating and cooling technology.