How Long Can A Generator Run On A Tank Of Gas?

How Long Can A Generator Run On A Tank Of Gas

How long can a generator run on a tank of gas? A generator can be a proper lifeline in an emergency. Generator manufacturers usually provide the runtime projected for a full gas tank. However, several variables might alter this. You can get the most use out of your generator by keeping an eye on these aspects and making the most of the gas tank.

How Long Can A Generator Run On A Tank Of Gas?

Manufacturers of generators always state how long they anticipate their products will operate on a full tank of gas. The following other factors can also impact runtimes:

Cold Weather

Most generators will use more fuel per hour during cold weather than they would under normal circumstances. The generator’s engine must run faster to compensate for the decreased efficiency, which consumes more gas. Suppose you live in a cold region and have a generator. In that case, it is a good idea to test it out before an emergency by running it on a full tank to see how long it will run over the winter.

High Altitude

Air pressure decreases with elevation. As a result, the generator’s engine has limited access to oxygen (the same principle applies when breathing at high altitudes). Due to the decreased oxygen supply, more fuel must be used each hour to sustain power production. Generators operate less efficiently and use more fuel than they would at sea level. Unburned gases are returned to the air intake for burning in specific generators’ exhaust gas recirculation loops, which can be installed as a workaround (reducing exhaust emissions).

High Load

A generator’s engine must use more fuel to produce the same power. Expect shorter runtimes if your household appliances are more significant than typical or use numerous devices simultaneously (for instance, using several power tools). If pushed over their continuous load rating, most generators will see some loss in efficiency. The circuit breakers on your generator might not be able to handle the current drawn by running air compressors and other high-load devices, necessitating the purchase of higher amperage units.

Low Fuel Level

The lowers the level in your generator’s tank when you try to restart it; the more complex its engine must work to suck up gas from the tank. Running a nearly empty tank dry can harm most generators’ engines irreparably (you should always follow the manufacturer’s suggested low-fuel-level protocol); this stresses the generator’s engine with no benefit. If you plan to store a generator long-term during a power outage, fill it with a stabilizer/conditioner like Sta-bill to prevent the fuel from degrading.

New vs. Old

Newer model generators are more effective than previous, less sophisticated versions. They generate cleaner emissions and utilize less fuel per watt of energy generated. However, these benefits come at a price because modern generators are sometimes more expensive.

How To Calculate How Long Your Generator Will Run On A Tank Of Gas

To determine how long your generator will run on a full tank of gas, you need to know its wattage and the fuel tank’s capacity. The formula is:

$((tank size in gallons x estimated output watts) / 30)) = hours of runtime

If you have a 500-watt generator with a six-gallon tank, the formula works out to:

$((6 x 500)) / 30 = 4.2 hours of runtime

So a six-gallon tank should provide you with about four and a half hours of power. Remember that many factors affect how long your generator runs on a full gas tank. It’ll also enable you to calculate the approximate runtime of your generator. However, it may change based on the gas quality and other factors.

How To Maximize Your Generator’s Runtime On The Gas Tank?

You can get the most runtime from your generator by doing the following:

  • Regular oil changes and checking for junk in the air filter and carburetor are good ways to maintain an engine. Make sure the fuel filter is clean if your generator has one.
  • Maintain a full tank of gas. Even though a full tank won’t keep the engine running any longer than one empty, it will help you make the most of every drop of fuel. (Prolong the life of your generator, too!)
  • Ensure all vents are free of debris, particularly around the fuel cap area.
  • If at all feasible, fill your generator with premium gas. Although it costs a bit extra, it offers higher performance and increases the lifespan of your generator.

How To Get The Most Out Of Your Generator’s Gas Tank?

You can improve your generator’s run time by learning how to conserve its power.

  1. A defective generator will consume more fuel to perform the same task, so be sure it is in good operating condition.
  2. You risk overloading your generator by using too many appliances at once or utilizing a large load, such as an oven.
  3. Avoid using extension cables and, if possible, plug appliances directly into your generator to take advantage of its power.
  4. To utilize tiny appliances that require a plug, use a DC-to-AC power inverter or adaptor.
  5. To lessen engine issues from using old gasoline, consider adding a gas stabilizer.
  6. If you aren’t using your generator for an extended time, put it somewhere cool and dry.
  7. To avoid being shorthanded, keep an eye on the level of your petrol tank.

What Factors Can Affect How Long You Run A Generator?

Generators are an excellent resource for emergency electricity. But before you can decide wisely, you must know how long it will last on a tank of gas. The following variables will impact how long a generator runs:


Because a generator only has so much power, the more work you ask it to accomplish, the shorter its runtime will be.


Low fuel efficiency and decreased engine power are two ways cold weather impacts a generator’s ability to produce power.

Fuel type

Up to 91,500 BTUs may be produced by one gallon of propane. One gallon of gasoline may provide about 124,000 BTUs. Since gasoline and propane generators use the same energy, the former will operate 36% longer.

 Manufacturer’s specs

Your generator’s manufacturer will provide an approximate runtime, which might change based on the load and outside conditions like temperature and fuel type.


Which Generators Are The Most Fuel-Efficient?

In generators, less fuel means more money saved. Similar to how you don’t want a gas-guzzling automobile, you don’t want a generator that spews pollutants. Our most fuel-efficient options were the cheapest vehicles. Let’s look at generator torque and wattage to determine power production relative to consumption.
When buying a generator, consider what appliances or tools it will power.
Check your owner’s handbook or contact the manufacturer to see what devices may operate on your portable generator.

How To Store Gasoline For Your Generator?

Gasoline lasts 6-12 months. Storing gasoline outside prevents humidity from causing corrosion. Clean your generator. Dusty equipment might create gasoline and engine difficulties. You’ll also need a way to charge your generator without depleting its fuel.
Once a month for 10 minutes, operate your generator. New gasoline may grow sour. Keeping generator gas for over six months might cause complications. Stale gas makes it hard to start your generator.
Keep your generator clean for proper operation. Dusty equipment might hinder motor performance, so clean your generator between usage.

How Long Will A Generator Run On 5 Gallons Of Gas?

Your generator will run on 5 gallons of gas for at least 6 to 8 hours. The duration typically relies on the size of the generator, the load it is under, and the fuel type (gasoline vs propane).



Misajidali is an exceptionally proficient electrician, possessing specialized knowledge in the realm of generators. With an extensive background spanning several years, he has solidified his reputation as a proficient authority in all facets of generator work, encompassing installation, upkeep, diagnostics, and restoration. Misajidali's profound understanding of electrical systems, coupled with his unwavering dedication to staying abreast of the latest industry innovations, render him a dependable and in-demand expert.

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