How Much Does It Cost to Run a Generator?

July 22, 2025 | Nate Cord

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More than 1 in 5 of us in the UK experience a power cut every year, with the leading cause being windstorms. If you need to keep the electricity on in case of a power cut, or you’re working or staying in an area without mains connection, generators are invaluable.

That said, a big question customers will ask us when it comes to buying a generator is: How much do they cost to run?

In this guide, we’ll break down generator running costs for you, from what type you need to factoring in service costs, plus some money-saving tips.

Generator Fuel Types

When it comes to calculating how expensive a generator is to run, a big factor will be the fuel type you choose. Here are the three main fuel types:

1. Petrol

If you’re looking for a generator as a backup for your home, for an outdoor event or commercially for farming and construction, petrol generators are generally cheaper upfront. However, with fluctuating petrol prices, these generators can have higher running costs in the long term.

2. Diesel

While diesel can be slightly more expensive than petrol, these generators can be more fuel-efficient and longer-lasting than petrol. This makes diesel generators a great investment long-term, particularly if you need a hard-working generator for industrial and commercial operations.

3. LPG or Natural Gas

LPG or natural gas generators are another fuel-efficient option, particularly for smaller-scale uses, such as a backup for your home or business. Running costs can be more stable for these generators, and they’re more eco-friendly and quiet as well.

While diesel generators may need more upfront investment, they can deliver fuel-efficient savings long term.

How to Calculate Your Generator Fuel Cost

As you’ll now know, some kinds of generator fuel are more efficient than others. When it comes to running your generator, fuel consumption is going to be your main cost.

So, let’s calculate it. Here’s how to estimate the fuel cost of your generator in four steps:

Find the fuel efficiency of your generator. You can usually find this stated as litres per hour (L/h) in the generator’s specifications. If not, divide the fuel capacity by the run time in hours.
Find the fuel price in your area per litre. Here’s a handy tool to find yours.
Multiply the fuel price per hour by the cost per litre.
This is your approximate cost per hour.

For example, say you’re considering the Evopower UKC300ECO 3-phase Diesel Generator, which is generally for industrial use:

The fuel capacity is 460L
The run time is 15.5 hours
The fuel efficiency is 460 ÷ 15.5 = 29.68L/h
The diesel price in your area is £1.28/L
The cost per hour is 29.68 x 1.28 = £37.99/h

If you need support calculating the generator power you need, our calculator can help. You can browse our complete range of generators here and, for additional advice, call us on 01639 849847.

The Evopower UKC300ECO 3-phase Diesel Generator is an example of a diesel generator for commercial use, with a greater cost per hour than, for example, a smaller generator for camping or home backup.

Generator Maintenance Costs

Now you know your generator’s fuel cost, you’ll have a much better idea of how much it costs to run. Now, let’s cover the maintenance your generator will need to keep it running efficiently and for longer.

As a rule of thumb, your generator will need regular oil changes and air filter replacements. For petrol generators, you’ll also need to replace spark plugs.

If you’re running a small to mid-size generator for your home or small business, your maintenance costs will depend on how often you use the generator and whether you decide to carry out the work yourself or bring in an expert.

By comparison, large commercial generators can cost a lot more to maintain, especially as you’ll need to factor in routine load testing, coolant checks and automatic transfer switch (ATS) systems by manufacturer-certified technicians.

If you use a generator for your home or small business, maintenance costs will depend on how often you use the generator and whether or not you feel confident carrying out the work yourself.

Examples of Generator Running Costs

As you might have noticed, the cost of running a generator will vary hugely depending on your needs. Generators vary in size, which is measured in kilowatts (kW) or kilovolt-amperes (kVA).

To give you an idea of how generator size affects your running costs, here are a few examples:

Small generators (up to 3kW) for camping or DIY will cost about £1.50 to £3 per hour to run, depending on the load.
Medium generators (3-7 kW), which you might use for outdoor events, usually cost around £2.50 to £6 per hour.
Large generators (above 7kW) for home or small business backup can cost £5 to £15 per hour or more, or upwards of £38 per hour as we’ve seen for industrial sites.

Understanding Generator Running Costs

We hope you now have a much better idea of how much it costs to run a generator, whether it’s as a backup for your home or for commercial purposes.

To learn more about generators, read our blog, including ‘How Quiet Are Silent Generators?’ and ‘Inverter Generators vs Traditional Generators’.

If you’re looking for a generator, we can help you find the ideal option tailored to your requirements. Explore our comprehensive range of generators here.

For expert advice on choosing your generator, contact our team using this form or via phone at 01639849847.