Buying guide · Fuel types
Which fuel
fits your home.
Two generators can be identical on the spec sheet and still feel completely different the night the power goes out. Fuel is why. It decides how long you run, how much you store, what you pay over a decade, and whether you ever have to think about it at all. Here is how the four choices really compare.
01 — At a glance
The four fuels, side by side.
Every generator we sell runs on one of these — or, in the case of dual-fuel, two of them at once. Start here to narrow the field, then read the deep-dive on whichever column you keep coming back to.
Gasoline Portable |
Propane Portable · standby |
Hands-off Natural gas Standby only |
Diesel Standby · commercial |
|
|---|---|---|---|---|
| Runtime per fill | 8 – 18 hr | 1 – 7 days | Unlimited | 1 – 3 days |
| Shelf life | 3 – 6 months, stabilized | Indefinite | Piped in — none to store | 6 – 12 months, treated |
| Refueling | By hand, with cans | Swap or refill tanks | Never | By hand or fuel service |
| Upfront cost | Lowest | Highest | ||
| Running cost | Cheapest to run | |||
| Clean burn | Cleanest | |||
| Best for | Occasional outages, lowest budget | Flexible backup, clean storage | Whole-home, set-and-forget | High-hour & commercial loads |
02 — In depth
Each fuel, on its own terms.
The matrix tells you where they differ. These tell you what it is like to live with each one.
Gasoline
The fuel almost everyone starts with. Gas generators are the most affordable to buy, the easiest to find on a shelf, and the simplest to understand — pour it in, pull the cord, you have power. The trade-off is that gasoline goes stale in a few months and you will be refilling by hand, can by can, through the length of any long outage.
- Lowest price to get into backup power
- Fuel is sold on every corner
- Light, portable, jobsite-friendly
- Stale in 3–6 months without stabilizer
- Stations close when the grid does
- Hand-refueling every 8–18 hours
Propane
Propane is the patient one. It sits in a tank for years without going bad, burns cleaner than gasoline, and is there the moment you need it — no trips to a closed gas station. You can run a portable off a barbecue cylinder or a standby off a buried 500-gallon tank. The cost is a small power derate versus gasoline and the need to keep tanks on hand.
- Stores indefinitely — buy once, keep for years
- Cleanest-burning of the liquid fuels
- Works portable or whole-home standby
- ~10% less output than gasoline
- You manage and swap the tanks
- Pressure can drop in deep cold
Natural gas
If your home already has a gas line, natural gas turns backup power into something you stop thinking about. A standby unit is plumbed straight to the utility, so it runs as long as the outage lasts — hours or weeks — with no refueling, no storage, and no tanks. It starts itself the instant the grid drops. The trade is that it is a fixed installation, never portable, and you depend on the gas main staying up.
- Truly unlimited runtime
- Nothing to store, refill, or stabilize
- Starts automatically — even when you are away
- Needs a gas line and professional install
- Permanent — never portable
- Relies on the gas main staying pressurized
Diesel
Diesel is the workhorse — the fuel you choose when the generator has to run long, hard, and often. Diesel engines are the most fuel-efficient under heavy load and built to log thousands of hours, which is why they back hospitals, farms, and job sites. For a typical house they are overkill: heavier, louder, pricier upfront, and the fuel can gel in hard cold without treatment.
- Most efficient under heavy, sustained load
- Engines built for thousands of hours
- Fuel stores longer than gasoline
- Highest upfront cost
- Heavier and louder than the rest
- Fuel can gel in deep cold
03 — Runtime & storage
How long it actually lasts.
Same load, four fuels, one mid-size generator. This is roughly what a tank or a connection buys you before you have to do something about it.
The honest headline: storage is the real variable, not the engine. A portable can technically run forever — if you can keep feeding it. A standby on natural gas needs nothing from you at all. Match the fuel to how long your outages run and how much fuel you are willing to keep on hand.
04 — The short answer
Which one is right for you.
Four common situations and the fuel that tends to win each one. Find the one closest to yours.
It starts itself, runs unlimited, and asks nothing of you. The premium upfront buys you a backup system you will forget exists until it saves your week.
For a handful of short outages a year, a gas portable is the most power per dollar. Keep stabilizer in the tank and a couple of full cans in the garage.
Propane stores for years and is ready the day you need it. A dual-fuel unit hedges your bet, running on propane normally and gasoline if you run short.
When the generator is a tool that works for a living, diesel efficiency and engine life pay back the higher sticker. Built to log the hours without complaint.
Size it first, then pick fuel.
Fuel is the second question. The first is how many watts you need. Run the numbers in two minutes and we will show you the right models — in every fuel that fits.
Not sure gas reaches you?
Whether natural gas is even an option comes down to your address and your meter. Tell us where you are and a specialist will sort out what is possible — same day.