Choosing a heating fuel is a 15- to 20-year decision for most homeowners. The two delivered fuels, heating oil and propane, reach homes by truck, sit in on-site tanks, and feed the same kinds of equipment, yet they differ in energy content, price, efficiency, and maintenance. The same gas-versus-propane trade-off shows up in backup power, where dual-fuel generators let homeowners switch fuels at the flip of a lever, but for whole-house heating the choice is usually one fuel or the other. This article compares the two on the numbers that actually drive annual bills.
Roughly five million U.S. households heat with oil, concentrated in the Northeast, and a similar number rely on propane, spread across the Midwest and South. Both fuels are priced per gallon but deliver very different amounts of energy per gallon, which is why a fuel cost calculator matters more than the sticker price on the tank.
Energy Content: What a Gallon Actually Delivers
A British thermal unit (BTU) is the energy needed to raise one pound of water by one degree Fahrenheit. Heating oil carries about 139,000 BTU per gallon, while propane carries about 91,500 BTU per gallon. A gallon of oil therefore holds about 1.5 times the energy of a gallon of propane, and that ratio drives every cost comparison that follows.
| Fuel | BTU per gallon | Typical appliance efficiency | Usable BTU per gallon |
|---|---|---|---|
| Heating oil | about 139,000 | 80 to 87 percent | 111,000 to 121,000 |
| Propane | about 91,500 | 90 to 97 percent | 82,000 to 89,000 |
The same gallon math applies beyond the furnace. A mid-size propane generator burns roughly one gallon per hour under a typical household load, and the consumption guide to how much propane a generator uses and what affects fuel consumption shows how quickly load, temperature, and generator size change the burn rate.
Why Efficiency Changes the Comparison
Propane appliances run hot and clean, so condensing propane furnaces routinely hit 95 percent AFUE or better. Oil equipment traditionally sat in the low to mid 80s, though condensing oil boilers now reach the low 90s. The usable BTU figures in the table reflect those differences: efficiency narrows the gap between the fuels, but oil still delivers more usable heat per gallon in almost every installation.
Appliance Efficiency Ratings
AFUE, or annual fuel utilization efficiency, measures how much of the fuel’s energy becomes heat over a typical season. A 95 percent AFUE furnace turns 95 cents of every fuel dollar into heat. Compare AFUE ratings, not just fuel prices, when you price replacement equipment.
Cost per Million BTU
Prices swing with crude oil markets, winter weather, and regional supply, so any comparison needs a common unit. The standard is cost per million BTU: divide the price per gallon by the BTU content, then multiply by one million. At $3.60 per gallon, oil costs about $25.9 per million BTU. At $2.90 per gallon, propane costs about $31.7 per million BTU.
| Price per gallon | Cost per million BTU |
|---|---|
| Oil at $3.20 | $23.1 |
| Oil at $3.60 | $25.9 |
| Oil at $4.00 | $28.8 |
| Propane at $2.60 | $28.4 |
| Propane at $2.90 | $31.7 |
| Propane at $3.20 | $35.0 |
Because oil packs about 1.5 times the energy per gallon, oil remains cheaper per BTU whenever its price stays below about 1.5 times the propane price. If propane sells for $2.90 and oil for $3.60, oil wins on energy cost even though the propane price looks lower at the pump. Over a full winter, a northern home burning 800 gallons of oil at $3.60 spends $2,880, while the same heat from propane at $2.90 lands closer to $3,600, and that gap is exactly what a fuel cost calculator exposes.
Equipment Costs and Dual-Fuel Options
Equipment costs tip the scale the other way. A new propane furnace typically costs less to install than an oil furnace, and propane tanks can be leased for a small annual fee, while oil tanks are usually owned and eventually replaced. A basic oil tank runs $300 to $500; owning a 500-gallon propane tank outright runs $1,200 or more, which is why many homeowners lease it instead. On the high end, a dual-fuel HVAC air-source heat pump plus propane backup provides electric heat in mild weather and switches to propane when temperatures drop, a configuration that can cut winter fuel use substantially and one that JLC Online covers in detail.
Break-Even Price
To find your break-even price, divide the oil price by 1.516, the energy ratio between the two fuels. If oil costs $3.60, propane matches its energy cost at about $2.37 per gallon. Any propane price above that means oil delivers more heat per dollar.
How to Use a Fuel Cost Calculator
A fuel cost calculator converts fuel prices, equipment efficiency, and annual consumption into an apples-to-apples number. The method works for any fuel pair, including the same comparison you would run when comparing energy output, cost, and safety of natural gas versus propane for home use; both gas fuels share the delivery-and-metering model, while oil stands apart with its own tank and truck logistics.
- Pull a full year of delivery or billing records and total the gallons
- Note the AFUE of your furnace or boiler, or plan for the efficiency of the replacement you are pricing
- Enter today’s delivered price per gallon for each fuel
- Compare cost per million BTU and projected annual cost
- Add equipment, tank, service, and maintenance costs before deciding
Inputs That Move the Number
- Degree days: colder winters mean more fuel, and NOAA publishes heating degree day data by location
- Home size and insulation: a leaky 2,000-square-foot house can burn half again as much fuel as a tight one
- Water heating: typically 15 to 25 percent of the annual load
- Appliance efficiency: a 10-point AFUE difference changes annual cost by roughly 10 percent
Reading Degree-Day Data
Heating degree days measure how far the average daily temperature falls below 65 degrees Fahrenheit. A location with 6,000 degree days needs roughly twice the heat of one with 3,000, before building differences are considered. Weather services publish degree-day totals so you can compare your winter to a normal winter.
Estimating Annual Consumption
Consumption estimates start from a simple baseline. A reasonably insulated 2,000-square-foot home in a northern climate burns about 700 to 900 gallons of heating oil per winter, or 1,000 to 1,300 gallons of propane. The propane number is larger because the fuel carries less energy per gallon, not because the house needs more heat.
The input-driven logic behind these estimates is the same one you would use with a concrete calculator when estimating materials for a slab or a driveway: define the surface, apply a per-unit rate, and multiply. Garbage in produces garbage out for fuel budgets just as it does for concrete orders.
Adjusting the Baseline
- Add 20 to 30 percent for older, poorly insulated homes
- Subtract 10 to 20 percent for recent window, attic, and air-sealing upgrades
- Add 15 to 25 percent when the same fuel heats domestic water
- Adjust for the thermostat: each degree of setback saves roughly 1 percent of heating fuel
Emissions, Safety, and Storage
Both fuels are hydrocarbons, but they are not equal at the chimney. EPA emissions factors put heating oil near 161 pounds of carbon dioxide per million BTU, while propane releases about 139 pounds, roughly 14 percent less. Propane also burns with far fewer particulates and leaves no soot in the appliance, which is why propane equipment stays cleaner between service visits.
Storage and safety differ too. Heating oil is a liquid that will contaminate soil if a tank leaks, and cleanup can cost more than the fuel ever did. Propane is stored as a pressurized liquid that vaporizes into a gas heavier than air, so it pools in low spots and carries an odorant that makes leaks easy to smell. Federal agencies publish estimating tools for environmental planning as well: the EPA’s stormwater calculator helps property owners and planners size green infrastructure for runoff management, a different problem but the same spreadsheet discipline.
Emissions by the Numbers
| Fuel | Pounds of CO2 per million BTU |
|---|---|
| Heating oil | about 161 |
| Propane | about 139 |
| Natural gas | about 117 |
The figures come from EPA emissions factors and work well for comparing fuels, though they are not the whole story: delivery, manufacturing, and tank lifecycle emissions add to both totals.
Choosing Between Oil and Propane
- Delivery reliability: which fuel has the more dependable supplier network in your area
- Tank ownership: leased propane tanks avoid capital cost; owned oil tanks avoid lease fees
- Equipment age: replacing an old oil system is the moment the comparison flips
- Price volatility: oil prices track crude more directly, while propane follows its own regional market
- Service network: confirm a technician who services the fuel you choose
- Environmental goals: propane’s cleaner burn and lower emissions per BTU may matter to you
Both systems are capable, and over time the cost gap between the fuels tends to wash out as prices cycle. Whatever you decide, run the numbers the same way you would for any major home project. A concrete calculator prices slab, beam, column, and footings with the same input-driven method a fuel calculator applies to a heating season; the only difference is the material. Fuel choice, like concrete design, rewards homeowners who measure before they spend.