How many hours can a generator run for?

eastern generator hire type of generator

A generator is a great way to ensure that you have access to reliable power when needed. Generators can be used for a wide range of purposes including during a power outage, on construction sites, for events and even outdoor camping activities.

Whether you are looking for a portable generator or one that is permanently installed, it’s important to know how many hours the generator can run on a single tank of fuel. How long your generator will last will depend on the size of the generator, what type of power it is running off of and how much load the appliance being powered by the generator has.

Portable Petrol Generators

There are many types of portable generators that vary in terms of the type of fuel, load size and functionality. These generators are amongst the most portable and common generators that support small loads such as power tools in your shed, outdoor camping situations or electrical appliances for emergencies at home.

As generators go they are the smallest compared to other generators because of their fuel tank and limited run time. Depending on the size of your generator, you can expect portable petrol or propane generators to run for a couple of hours up to 12 hours or more based on the size of the fuel tank.

Since fuel tanks are usually smaller, you’ll need to refuel portable propane generators more often as you continue to use it. This might be inconvenient especially if you are using a portable generator for an extended period of time. Smaller generators such as petrol or propane models might not run more than 12-15 hours before requiring refuelling. How long it lasts before refuelling will depend on the size of the fuel tank. Larger models can run for up to 18 hours with one full load of petrol depending on its wattage.

Prime Power and Standby Power Generators

If you’re looking to run large power loads continuously for long durations, prime power diesel generators are the best option. Industrial diesel generators generally have larger fuel tanks, are not as portable (you can’t just put it in the back of your truck or boot), able to power larger multiple devices or loads at once and are capable of longer run times. Similar to petrol generators with propane tanks, the run time of diesel generators depends on the size of their fuel tank.

You can buy or hire small, medium or large generators with varying fuel tank sizes. You can expect larger diesel generators to run for 500 hours at a time which is equal to three weeks of continuous use, however where possible it is recommended that you turn off your generator when not in use. This might be a bit difficult for standby generators as they turn off automatically.

The difference between prime power and standby generators is that standby generators operate automatically when the system detects the main power source has been cut off. This makes it ideal for home back-up power solutions when your home or business loses power from a blackout and then you’ll immediately be connected to an alternate power source. Prime power generators can be turned on or off when you need it to, so they’re capable of running for longer periods of time continuously.

Diesel generators have larger fuel tanks, which means that they can run longer before requiring refuelling. If you require the generator to provide power for your business, this will make a huge difference in terms of costs and management. How many hours a diesel generator can run on one tank of fuel depends entirely on how much it’s being used, its size and type.

If you need a diesel power generator immediately for emergency or other purposes, get in touch with our friendly team and we’ll assist with choosing the right diesel generator for your power solutions.

How to Choose the Right Generator

If you want to know what generator is best, you should ask yourself a couple of key questions before choosing the right generator for your power needs. How long your generator will last depends on the size of it and how you’re going to use it. You don’t want to hire or buy a generator that has too much capacity for your requirements.


What are you using your generator for?

  • Do you need it immediately for a temporary or permanent power solution?
  • Did you want to purchase or hire a generator?
  • Where or what are you planning on using it for? i.e. events, construction sites, commercial buildings, schools, aged care centres, shopping centres, businesses

How long do you need to have your generator run for?

  • Do you need it to run continuously?
  • How long is the duration that you need to run it for?

What do you need to power using the generator? (Sizing your generator)

  1. Make a list of all the appliances and equipment you may be using
  2. Check what unit of measurement your generator might be sized in such as kilowatts (kW) or kilo-volt-amperes (kVA)
  3. Provide the unit of measurement (such as voltage, wattage) for the appliances or equipment you’ll need to power and convert them if necessary into the same unit of measurement. Make a note of both starting and running voltage/wattage.
  4. Convert these units into the same unit your generator is sized in
  5. Determine how many devices you’ll need to run at any given time. This will make you aware of the highest starting wattage equipment and what else you’ll likely need to run. 
  6. Adding up all these devices will give you an estimated power outage you’ll need.

If you’re still unsure about the right diesel generator for your power needs, get in touch with our friendly team. We’ll be able to help you choose the best option based on your requirements. You’ll be able to get access to our comprehensive service by our qualified and experienced technicians who’ll take care of any installation, handling, and delivery when you need it 24/7.

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Contact us now to discuss your generator and power requirements and we will provide you with a customised quote.