Heating Oil vs Propane: Cost & Efficiency | heating.help
If your furnace or boiler is nearing the end of its life, or you just opened a fuel bill that made you flinch, you are probably weighing heating oil against propane and wondering which one actually costs less to run. The answer is not as simple as comparing price per gallon, because the two fuels pack very different amounts of energy into that gallon. Below is a side-by-side breakdown of real costs, BTU content, AFUE efficiency, equipment prices, and the hidden expenses that catch homeowners off guard.
Quick Answer: Which Fuel Costs Less?
In most US markets, propane and heating oil cost roughly the same to heat a home — within about 10% of each other — when you compare dollars per million BTU of delivered heat. Propane usually looks cheaper at the pump (per gallon) but delivers less heat per gallon. Heating oil costs more per gallon but burns hotter and longer per fill.
The deciding factors are almost always local:
- What you pay per gallon in your ZIP code, including delivery fees and contract pricing.
- The efficiency (AFUE) of the equipment — a 95% AFUE propane furnace uses far less fuel than a 30-year-old oil boiler at 78% AFUE.
- Tank, delivery, and service costs, which can swing the math by $500 or more per year.
Heating Oil vs Propane at a Glance
| Factor | Heating Oil (No. 2) | Propane |
|---|---|---|
| Energy per gallon | ~138,500 BTU | ~91,500 BTU |
| Typical US price (2026) | $3.70–$4.60/gal | $2.30–$3.50/gal |
| Typical AFUE — furnaces | 80%–90% (condensing oil units up to 95%) | 80%–98% (condensing) |
| Typical AFUE — boilers | 82%–88% (condensing up to 95%) | 84%–96% |
| Cost per million BTU (delivered heat)* | ~$33–$40 | ~$30–$40 |
| Tank size, typical home | 275 gal (aboveground) | 500 or 1,000 gal |
| Tank ownership | Usually homeowner-owned | Often leased from supplier |
| Equipment life | 20–30 years (furnace), 25+ (boiler) | 15–20 years |
| Availability | Mostly Northeast & Mid-Atlantic | Nationwide, strong in rural areas |
| CO₂ emissions | ~161 lb per MMBTU | ~139 lb per MMBTU |
*Assumes 85% AFUE for oil and 90%–95% AFUE for propane at mid-range fuel prices.
Energy Content: BTU per Gallon Matters More Than Price per Gallon
The single biggest mistake homeowners make in the heating oil vs propane debate is comparing sticker price per gallon.
- No. 2 heating oil: about 138,500 BTU per gallon
- Propane: about 91,500 BTU per gallon
Heating oil carries roughly 51% more energy per gallon. That is why a standard 275-gallon oil tank holds about 38 million BTU (MMBTU) at full capacity, while a 500-gallon propane tank — filled to the industry-standard 80% to allow for expansion — holds about 36.6 MMBTU. A smaller tank of oil can hold as much usable heat as a bigger tank of propane.
Cost per Million BTU: The Only Fair Comparison
Here is how the math works out for a typical 2,000 sq ft home in a cold climate that needs 75 MMBTU of delivered heat per season:
| Heating Oil @ 85% AFUE, $4.20/gal | Propane @ 95% AFUE, $2.75/gal | Propane @ 80% AFUE, $2.75/gal | |
|---|---|---|---|
| Fuel input needed | 88.2 MMBTU | 78.9 MMBTU | 93.8 MMBTU |
| Gallons required | ~637 gal | ~863 gal | ~1,024 gal |
| Annual fuel cost | ~$2,675 | ~$2,373 | ~$2,817 |
| Cost per MMBTU delivered | ~$35.70 | ~$31.60 | ~$37.60 |
The takeaway: efficiency moves the needle as much as fuel type. A high-efficiency condensing propane furnace can beat oil on annual cost even when propane costs more per MMBTU at the tank. A mid-efficiency oil boiler beats an old oversized propane unit every time.
Efficiency Ratings Explained (AFUE)
AFUE — Annual Fuel Utilization Efficiency — tells you what percentage of fuel energy becomes heat in your home instead of going up the flue. Look for it on the yellow EnergyGuide label.
- 80% AFUE means 20 cents of every fuel dollar escapes as exhaust.
- 95% AFUE means 5 cents escapes.
- Federal minimum for new residential furnaces is in the low 80s AFUE; ENERGY STAR certification requires at least 95% AFUE for gas/propane furnaces and 85% AFUE for oil furnaces. In practice, most new oil-fired equipment sold today is non-condensing, while propane has a mature market of condensing, modulating units.
Oil-Fired Equipment
- Oil furnaces: typically 80%–86% AFUE; high-efficiency condensing oil furnaces reach 90%–95% but are a small share of the market and need ultra-low-sulfur fuel (15 ppm) or bioheat blends.
- Oil boilers: 82%–88% AFUE; condensing oil boilers top out around 95%.
- Strength: oil equipment is rugged. Heat exchangers and boilers routinely last 25–30 years with annual service.
- Weakness: efficiency gains have been incremental, and oil burners need annual nozzle, filter, and strainer service.
Propane Equipment
- Propane furnaces: 80%–98% AFUE; condensing modulating models with variable-speed blowers lead the market.
- Propane boilers: 84%–96% AFUE, with excellent modulation and outdoor-reset controls.
- Strength: clean-burning, low-maintenance, sealed-combustion options that draw air from outdoors.
- Weakness: shorter service life (15–20 years) and higher repair costs on complex condensing models.
Equipment and Installation Costs
| Project | Typical US Cost (Installed) |
|---|---|
| Replace oil furnace | $3,500–$8,000 |
| Replace oil boiler | $5,000–$10,000 |
| New aboveground oil tank (275 gal) | $1,500–$3,500 |
| Oil tank removal / disposal | $500–$1,500 |
| Replace propane furnace | $2,500–$6,000 |
| Replace propane boiler | $4,000–$8,500 |
| New propane tank (purchased, 500 gal) | $1,200–$2,500 |
| Propane tank leased | Often $0 with a supply contract |
| Oil-to-propane conversion (all-in) | $4,000–$9,000 |
| Propane-to-oil conversion (all-in) | $6,000–$12,000 |
Propane equipment and tank installation are generally cheaper up front, and you can often review available propane installation costs and rebates by region before committing to a conversion. Oil systems cost more to install — especially if a new tank, oil line, or chimney liner is needed — but the equipment tends to outlast propane appliances by five to ten years.
Hidden Costs Homeowners Forget
Tank Ownership and Replacement
A 275-gallon steel oil tank has a service life of roughly 20–30 years. Indoor tanks last longer; outdoor tanks in wet climates fail sooner. A leaking oil tank is an environmental liability that can cost $3,000–$15,000+ to remediate soil contamination. Budget for tank inspection annually and plan on replacement at some point.
Propane tanks are usually leased from the supplier, which shifts maintenance to the company — but it also locks you into that supplier for refills, sometimes at above-market rates.
Delivery, Contracts, and Minimum Orders
- Heating oil: common minimum delivery is 100 gallons; automatic delivery and pre-buy/cap-price contracts smooth out heating oil prices that spike in November and January. Cash-on-delivery discounts of 5–15 cents per gallon are common.
- Propane: typical minimum is 50–100 gallons, but small tanks mean more frequent fill-ups and a higher per-gallon “will-call” price. Automatic delivery and “keep-full” programs cost more per gallon than shopping around.
Maintenance and Service
- Oil: $150–$350 per year for an annual tune-up including nozzle, filter, and combustion test. Skipping it costs efficiency and reliability.
- Propane: $100–$250 per year. Fewer wear parts, but condensate traps on high-efficiency units need attention.
Insurance and Code Requirements
Many insurers require oil tanks to be indoors, on legs, or in a containment basin, and some require tank-test documentation. Propane requires clearance from ignition sources, proper relief valves, and in some jurisdictions a setback from property lines. Both need permits for installation and conversion.
Availability: Where You Live Often Decides for You
- Heating oil serves roughly 5 million US homes, heavily concentrated in the Northeast and Mid-Atlantic — New York, Pennsylvania, Massachusetts, Connecticut, Maine, New Hampshire, Rhode Island, and New Jersey. If you are outside that region, delivery may be expensive or unavailable.
- Propane reaches about 5–6% of US homes and is the dominant off-grid fuel in rural areas nationwide, from the Midwest to the South to the Mountain West.
If you are in the Northeast and already have a tank and a burner, sticking with heating oil heating systems is usually the path of least resistance. If you are building or replacing equipment far from oil-delivery routes, propane almost always wins on logistics.
Environmental and Safety Comparison
| Heating Oil | Propane | |
|---|---|---|
| CO₂ per MMBTU | ~161 lb | ~139 lb |
| Sulfur content | 15 ppm (ultra-low sulfur) in most states | Essentially sulfur-free |
| Particulate matter | Low with modern burners | Very low |
| Renewable options | Bioheat blends (B5–B20), up to B100 in some systems | Renewable propane (limited availability) |
| Leak risk | Slow leaks, soil/groundwater contamination | Fast leaks, explosive vapor range (2.1%–9.5% in air) |
| Odorant | Distinctive oil odor | Ethyl mercaptan added |
Propane is the cleaner-burning fuel and produces about 14% less CO₂ per unit of heat. Heating oil’s risk profile is about slow leaks and tank corrosion; propane’s is about gas accumulation in basements and crawl spaces, which is why propane detectors and proper venting are non-negotiable. Neither fuel is inherently unsafe in a well-maintained system installed to code.
Which Fuel Should You Choose?
Lean toward heating oil if:
- You live in the Northeast with established delivery routes and a service contract.
- You already own a tank in good condition and your boiler has life left.
- You value long equipment life and straightforward, low-tech repairs.
- You want access to bioheat blends that lower your carbon footprint without new equipment.
Lean toward propane if:
- You are outside oil-delivery territory or building new construction.
- You want a high-efficiency condensing furnace or boiler (95%–98% AFUE).
- You prefer leasing a tank rather than owning one.
- You also want propane for cooking, water heating, or a generator.
Consider a heat pump instead if you are replacing equipment anyway — modern cold-climate heat pumps plus federal incentives can undercut both fuels on annual operating cost, especially in mild climates.
Can You Switch? What a Conversion Involves
Switching fuels is a mechanical project, not a fuel-order change. An oil-to-propane conversion typically includes:
- New propane furnace or boiler (or a burner/ orifice conversion kit, rarely practical).
- New propane tank, regulator, and gas line to the appliance.
- Oil tank pump-out, cleaning, and removal (or abandonment in place per local code).
- Permit, inspection, and often a new vent or chimney liner.
Budget $4,000–$9,000 for oil-to-propane and $6,000–$12,000 for propane-to-oil. Expect 5–10 years of fuel savings to pay back a conversion, so most homeowners only switch when the existing equipment fails.
Frequently Asked Questions
Is propane cheaper than heating oil?
Per gallon, yes — typically $2.30–$3.50 versus $3.70–$4.60. Per unit of delivered heat, they are close. A gallon of heating oil holds about 138,500 BTU versus about 91,500 BTU for propane, so the gap narrows to roughly 10% once you factor in AFUE. High-efficiency propane systems often win; oil wins when propane is bought at small-tank will-call prices.
How many BTU are in a gallon of heating oil versus propane?
No. 2 heating oil contains about 138,500 BTU per gallon; propane contains about 91,500 BTU per gallon. Heating oil is roughly 51% more energy-dense, so oil tanks can be smaller and deliveries less frequent for the same heat output.
Do I need a new furnace to switch from heating oil to propane?
Yes. Oil and propane appliances use different burners, orifices, fuel lines, and venting. A full conversion — new equipment, tank, fuel line, oil tank removal, and permits — generally runs $4,000–$9,000 in the US before incentives.
Conclusion
Heating oil and propane are closer in real operating cost than either fuel company wants you to believe. Propane wins on price per gallon, cleaner combustion, higher achievable AFUE (up to 98%), and nationwide availability; heating oil wins on energy density, equipment longevity, and stable delivery infrastructure in the Northeast. The honest answer is that your local fuel price and your equipment’s AFUE matter more than the fuel name on the tank. Run the cost-per-million-BTU math with your own recent fuel bills and your equipment’s rating plate, then factor in tank ownership, maintenance, and conversion costs. If your existing system is 80% AFUE or better and your tank is sound, staying put usually beats switching. If you are facing a full replacement anyway, compare a high-efficiency propane system and a cold-climate heat pump against a new oil unit — that is where the real savings in 2026 and beyond will come from.