The Best Propane Generators
The best propane (LP) generators compared — portable dual-fuel and whole-house standby picks, with real runtimes per tank, the wattage you lose against gasoline, and what propane actually costs to run.
Propane’s one decisive advantage over gasoline is that it keeps. A generator that sits in the garage eleven months of the year fails to start for one overwhelming reason — stale fuel in the carburetor — and propane simply removes that failure mode. The trade is about 10% fewer watts than the same engine makes on gas, plus tanks to store. That is why almost every propane generator worth buying is a dual-fuel unit: propane for readiness, gasoline for the day you need every last watt.
| Model | Best for | Running watts on propane | Notes |
|---|---|---|---|
| Westinghouse WGen9500DF | Best for home backup | 8,500 running on propane (9,500 on gas) | Transfer-switch-ready with remote start — covers a home’s essentials on either fuel. |
| DuroMax XP13000EH | Best high-output | 10,500 running on propane | The most running watts per dollar in the dual-fuel class; heavy, and louder than an inverter. |
| Champion 100519 (201157) | Best value | 7,500 running on propane | Champion’s US support network behind a mid-size dual-fuel at a lower price. |
| Champion 2500-watt dual-fuel inverter | Best quiet & portable | 1,850 running on propane | Light and quiet enough for a campsite, and enough for a fridge during an outage. |
| Generac Guardian 22 kW (LP) | Best whole-house standby | 19.5 kW on propane (22 kW on natural gas) | Permanently installed, starts itself, runs off a 250–500 gallon tank. Dealer-installed. |
How long a propane generator runs per tank
Runtime is the question buyers actually ask, and the honest answer is a range, because it depends almost entirely on load. The figures below assume a mid-size portable of 5,000–7,500 running watts at heavy load, and the same unit running a light essentials load — fridge, furnace blower, lights, Wi-Fi. A whole-house standby burns roughly two to three times as much per hour, so halve the essentials column again for a 22 kW unit.
| Tank size | Heavy load | Essentials load |
|---|---|---|
| 20 lb tank (≈4.6 gal) | 5 hours | 8–10 hours |
| 100 gal tank (≈80 gal usable) | ~40 hours | 100–130 hours |
| 250 gal tank (≈200 gal usable) | ~80 hours | 200+ hours |
| 500 gal tank (≈400 gal usable) | ~160 hours | 400+ hours |
How to choose a propane generator
- Size it on the propane rating, not the gas rating. Manufacturers lead with the gasoline number because it is the bigger one. If you plan to run on propane, use the propane figure — work out what you actually need with the sizing calculator first.
- Match the tank to the outage you are planning for. A 20 lb grill tank buys you an evening. Anything longer means a 100 gallon tank or a permanent 250–500 gallon tank, which is also what makes a standby unit practical.
- Plan for cold. Propane vaporizes more slowly in deep cold, so a small tank feeding a hard-working generator can starve. Larger tanks have more surface area and handle winter far better — worth knowing before a January outage.
- Sort the connection out before you need it. To run household circuits you need a transfer switch or interlock fitted by an electrician, not an extension cord through a window.
Propane, natural gas or dual-fuel?
If your house has a gas line, natural gas beats propane on convenience and running cost — there is no tank to fill and the runtime is effectively unlimited. Propane wins where there is no gas service, and it is the only one of the two that works with a portable you can take to a job site or a campsite. Want all three options in one machine? See the best tri-fuel generators. Comparing the fuels head-on is covered in the portable versus standby guide.
Watts, runtimes and prices are planning estimates that change by model and load — confirm current specs on the manufacturer’s or retailer’s page. Run a generator outdoors only, well away from doors, windows and vents: the exhaust contains carbon monoxide. Propane tanks must be stored and connected to the manufacturer’s instructions. As an Amazon Associate we earn from qualifying purchases.
Frequently asked questions
How long will a 20 lb propane tank run a generator?
A standard 20 lb (grill-size) tank holds about 4.6 gallons of propane. A mid-size portable of roughly 5,000–7,500 running watts burns about 0.5–1 gallon per hour depending on load, so expect roughly 5 hours at heavy load and 8–10 hours at a light essentials load. Two or three tanks is the practical minimum to carry a household through an overnight outage without a refill run.
What are the downsides of a propane generator?
Three real ones. You lose roughly 10% of the rated wattage against gasoline, because propane carries less energy per unit burned. You have to store and handle tanks — a 20 lb tank only buys you hours, so meaningful backup means a 100 gallon tank or larger. And in deep cold, tank pressure drops as the liquid struggles to vaporize, which can starve a generator running hard off a small tank. Against that: propane stores for years without going stale, which is exactly what gasoline cannot do.
How long will 100 gallons of propane last for a generator?
For a portable running a home’s essentials, roughly 4–6 days: at about 0.75–1 gallon per hour at half load, 100 gallons is 100–130 running hours, and few people run a generator around the clock. A whole-house standby is thirstier — a 22 kW unit at half load burns closer to 2–2.5 gallons per hour, so the same 100 gallons is about 40–50 hours, or two days of continuous running.
How long will a 250 gallon propane tank run a Generac generator?
A 250 gallon tank is filled to about 80% — roughly 200 usable gallons. A 22 kW Generac at half load burns in the region of 2.4 gallons per hour, which works out to about 80 hours, or three to three and a half days of continuous running. Careful load management stretches that considerably; running central air the whole time shortens it. For longer outages, a 500 or 1,000 gallon tank is the usual answer.
Is propane or gasoline better for a generator?
For a generator that sits unused between outages, propane wins — it stays usable for years, so it will not gum up a carburetor, which is the single most common reason a stored generator will not start. Gasoline wins on raw output (about 10% more watts) and on availability if you have no tank. That is why dual-fuel is so popular: store propane for readiness, keep gas on hand for the days you need every last watt.