Propane vs Kerosene Heater: Cost, Safety and Which to Buy

For most people, propane is the better pick. Indoor-rated propane heaters shut themselves off when oxygen runs low, and the fuel stays sealed in a cylinder you keep outside. At October 2026 prices it also costs less per unit of heat, unless your kerosene sells for under about $4 a gallon. Kerosene makes sense for a ventilated garage or workshop where you want many hours from one fill and can buy certified 1-K kerosene, but it smells more when something is off and the fuel goes stale between seasons.

Every figure in the table comes from a maker page or manual, the EIA, CPSC or NFPA, checked in October 2026.

Which costs less to run

Start with how much heat each gallon holds. The EIA's Btu conversion page puts propane at 91,452 BTU per gallon. For kerosene, the EIA uses 5.670 million BTU per barrel, a factor it lists in its heat content source notes. A barrel is 42 gallons, so that works out to about 135,000 BTU per gallon. A gallon of kerosene carries roughly 48 percent more heat than a gallon of propane.

Price is the other half. The EIA's weekly heating oil and propane update gives a US average residential propane price of $2.730 a gallon for the week of October 26, 2026, excluding taxes. The EIA does not publish a weekly kerosene price. The nearest series it publishes is residential heating oil, at $6.233 a gallon the same week. Heating oil is a different fuel from 1-K kerosene, so treat it as a stand-in, not the price you will pay at the pump.

Here is the arithmetic for 100,000 BTU of heat:

• Propane: 100,000 / 91,452 = 1.09 gallons, times $2.730 = about $2.99.
• Kerosene at the heating oil price: 100,000 / 135,000 = 0.74 gallons, times $6.233 = about $4.62.
• Break-even: kerosene matches propane at about $4.03 a gallon ($2.99 x 1.35).

So the quick test is your local kerosene price. Pay less than about $4 a gallon and kerosene heat is cheaper than bulk propane at the EIA average. Pay more and propane wins. Both heater types are unvented, so their exhaust and its heat stay in the space; we compare the fuel's heat content and make no efficiency adjustment.

Your fuel source changes the answer. The EIA price is for bulk residential propane, while 1 lb cylinders and tank exchanges cost more per gallon, so use what you pay. Our propane runtime calculator turns your heater's BTU and your tank size into hours and cost.

Indoor use: the rating, the sensor and the law

Propane

Indoor-rated propane heaters have an oxygen depletion sensor (ODS). CPSC's release on ODS heaters says the sensor closes the gas valve when oxygen drops below 18 percent, and that older heaters without one are for outdoor use only and must never be used indoors. Mr. Heater lists its Little Buddy, Portable Buddy and Big Buddy as indoor-safe, each with an ODS and a tip-over shut-off.

Indoor-safe still has limits. The Portable Buddy manual calls it a heater for recreational and emergency indoor use, asks for a vent of at least 9 square inches at the ceiling and at floor level, and says never to bring a refillable cylinder indoors. Mr. Heater's product rules page says Massachusetts and Canada do not allow propane heaters indoors, and that most cities do not allow gas heaters in high-rise buildings or apartments. Our guide on using a propane heater indoors covers those rules in more depth.

Kerosene

Sengoku lists no ODS on its kerosene heaters. It lists its HeatMate HMN-110 for indoor and outdoor use, with an automatic safety shut-off and a tip-over switch. Its manual warns that a shortage of oxygen can cause improper combustion and produce carbon monoxide.

The ventilation rule is in the HMN-110 operator's manual. If the room has less than 200 cubic feet of air for each 1,000 BTU of heater rating, keep the door to the next room open or open a window at least 1 inch. For a 10,000 BTU heater, that means a room under 2,000 cubic feet, or about 250 square feet with an 8-foot ceiling. The manual also rules out bathrooms and any small room with the door closed.

CPSC's kerosene heater safety sheet gives the same advice: run the heater with the door open to the rest of the house, and open a window about an inch if the door is closed or the house is tight. On the legal side, NFPA's 2026 fire safety desk reference says portable kerosene heaters are illegal in some communities, so check with your local fire department first. Our kerosene heater safety guide walks through the indoor routine.

Neither fuel gets a pass on carbon monoxide. NFPA notes that unvented gas heaters with an ODS still produce CO, carbon dioxide and nitrogen dioxide, and recommends them for emergency heat only. CPSC says kerosene heaters produce low levels of CO and nitrogen dioxide.

Odor, soot and air quality

This is the biggest day-to-day difference. Propane has an odorant added on purpose so you can smell a leak, and the Portable Buddy manual says any gas odor is your signal to act at once. For other smells, Mr. Heater's Buddy series FAQ puts them down to chemicals in the air being drawn into the burner, and suggests trying a different tank.

Kerosene heaters smell when the fuel or the burn is wrong. The Sengoku manual lists the causes of smoke or odor as a flame set too high, a draft, a burner that is not level, carbon or tar on the wick, and contaminated kerosene. Running below the minimum wick setting can produce odor or CO, and poor combustion leaves soot. A slight smell on a new heater is normal for the first 3 to 4 hours, Sengoku says, while anticorrosion oil burns off. If yours smells all the time, our list of ways to stop kerosene heater smell starts with the fuel.

Fuel grade matters more with kerosene. CPSC says to use only water-clear 1-K grade, bought from a dealer who can certify it, because other grades release more pollutants and can look the same.

Fuel storage and shelf life

Propane stays in a sealed steel cylinder. NFPA 1, as summarized in NFPA's outdoor heater fact sheet, says cylinders must not be stored inside a building. None of the maker or government pages we checked gives a shelf life for propane itself.

Kerosene needs more care. Sengoku says to store it in a container clearly marked "Kerosene", never red, outside the living area, in a cool, dark place out of the sun. CPSC adds that kerosene cans are usually blue and should be kept apart from gasoline. Sengoku also says not to keep kerosene over from the previous season, because old fuel deteriorates, and to empty the tank before you store the heater for summer.

Refueling follows the same outdoor rule on both. The Buddy manual says to attach or detach a cylinder outdoors, away from flames, with the heater cool. Sengoku and CPSC say to refuel a kerosene heater outdoors, only after it is off and cool.

Heat output and power needs

Indoor-rated portables are small on both sides. Mr. Heater's indoor-safe Buddy heaters run from 3,800 BTU (Little Buddy, 95 square feet) to 18,000 BTU (Big Buddy, 450 square feet). Sengoku's indoor-rated kerosene heaters are 10,000 BTU for the HMN-110 (400 square feet) and 23,500 BTU for the HeatMate HMC-23K (1,000 square feet). Treat maker coverage figures as a best case in a mild, insulated space.

Run time favors kerosene. Sengoku rates the HMN-110 at 14 hours on its 1.2-gallon tank. The Portable Buddy runs about 3 hours on high from a 1 lb cylinder, and the Big Buddy up to 11 hours on two.

For job sites, both fuels come in forced-air heaters that are not indoor-safe. Mr. Heater's MH60QFAV propane model runs from 30,000 to 60,000 BTU, needs a 110-volt outlet, and is for outdoors or well-ventilated areas. Its kerosene line runs from the 50,000 BTU MH50KR to the 210,000 BTU MH210KTR, needs electricity, and burns kerosene, diesel, home heating oil or JP-8. All five kerosene models showed as sold out on Mr. Heater's store in late October 2026. Our torpedo heater picks compare more of them.

Ignition is simple on the indoor units. The Buddy heaters use a Piezo igniter. The Sengoku heaters light with a battery-powered push button and need no matches or mains power.

Which one to pick

• A power cut or a cold room for a few hours: an indoor-safe propane heater with an ODS.
• A garage or workshop you heat all day: kerosene if your local price is under about $4 a gallon and you can ventilate; propane otherwise.
• A job site or open barn: a forced-air heater on either fuel, outdoors or in a well-ventilated space.
• An apartment: neither until you check the local code, since Mr. Heater says most cities ban gas heaters in apartments.

Whichever you choose, never run it while you sleep. CPSC's carbon monoxide Q&A says never to run unvented fuel-burning appliances in a room where people are sleeping. Both makers say never to leave the heater unattended while it burns, and NFPA says to keep anything that can burn at least 3 feet away. For the full propane lineup, see our propane heater picks.

If you smell gas or a CO alarm sounds

If you smell gas near a propane heater, do not light it or touch any switches. Get everyone out, close the cylinder valve if you can do it safely, and call your propane supplier and the fire department from outside. That is the order the Portable Buddy manual gives, and NFPA says to call 911 and the gas company for a strong gas odor.

Fit a CO alarm on every level of the home and outside sleeping areas, as CPSC advises. If it sounds, do not look for the source. Move outside to fresh air, call 911, and stay out until responders say it is safe.