Which Generator Is Best: Petrol or Diesel​? Your Guide

June 17, 2025 | Nate Cord

If you’re on the hunt for a generator, you’re likely going to come across two types of fuel – petrol and diesel. But if you’re scratching your head trying to figure out which one is better for your needs – don’t worry, you’re not alone.

Whether you’re prepping for a power outage at home, setting up a remote worksite, or just want some backup for your next camping trip, picking the right generator can make a huge difference.

In this expert guide, we’ll break down the pros and cons of petrol vs. diesel generators, helping you know exactly which type suits your needs best.

What is a Petrol Generator and How Do They Work?

As it says in the name, a petrol generator runs on petrol and uses an engine to turn it into electricity.

These generators are great for things like powering tools on a building site, providing backup power at home during blackouts, or running equipment outdoors where there’s no mains supply.

In technical terms, a petrol generator works by burning petrol to create mechanical energy, which it then turns into electricity. When the generator is turned on, the engine draws in air and petrol, mixes them together, and ignites the mixture inside the engine’s cylinders. This controlled explosion pushes pistons up and down, which spins a crankshaft.

That spinning crankshaft is connected to an alternator, and the electricity produced can then be used to power anything from power tools to household appliances.

Key Benefits of a Petrol Generator

1. Quick Starting

One of the biggest benefits of using a petrol generator is how quickly and smoothly they start. Unlike other types of generators, petrol engines generally don’t need much warming up and respond well even in colder weather, meaning you can get power going almost immediately after turning it on.

This is especially handy in emergencies or when you’re on a tight schedule and need things powered fast (like for catering or farming industries).

2. Petrol is a Widely Available Fuel

One super convenient benefit of choosing a petrol generator is that this is one of the most common fuels around, so it’s easy to get hold of almost anywhere.

This naturally makes refuelling your generator quick and hassle-free, especially compared to fuels that might be harder to source. This convenience is a big plus if you need reliable power on the go or during emergencies.

Petrol is also cheaper to buy than diesel here in the UK, so you will likely save money in running costs using a small petrol generator over a diesel one.

3. Lightweight and portable

Another reason why many opt for petrol is that these generators tend to be relatively smaller and lighter than diesel models, making them easy to carry around or move where you need them.

This is especially useful if you need to shift your generator between different locations – whether that’s around a worksite, between events, or simply from your garage to your garden. Many petrol models even come with built-in handles or wheels to make transport even more convenient.

Check out our range of high-performance petrol generators from leading brands, including the Senci SC1400i Inverter Petrol Generator, Pramac PX4000 Petrol Framed Mounted Generator and the Hyundai HY6500SEi Petrol Inverter Generator Electric Start.

Potential Drawbacks of a Petrol Generator

Generally speaking, petrol generators are often less fuel-efficient than diesel models once you go above 4-5kW, which means they burn through more fuel to produce the same amount of electricity. This might not seem like a big deal if you’re only using the generator occasionally, but over time, especially if you’re running it for several hours a day, those extra litres can really add up.

For example, if you’re using a generator for home backup power during long outages or to run equipment daily, you’ll find yourself refuelling more often and spending more on petrol than you would with diesel.

Another drawback is that petrol generators are more likely to encounter issues that require maintenance or part replacements.

What is a Diesel Generator?

Again, as the name suggests, a diesel generator runs on diesel fuel.

Diesel generators are known for being tough, reliable, and fuel-efficient, especially when running for long periods. Due to their size and output, diesel generators are typically better for installations requiring more extensive power, such as on work sites, in businesses, hospitals, and anywhere that needs dependable backup power.

As these engines are built to be more robust and durable than petrol engines, they can typically last a little longer with proper maintenance.

Key Benefits of a Diesel Generator

1. They are Better for Heavy-Duty Use

One of the standout benefits of diesel generators is their ability to handle heavy electrical loads without breaking a sweat. This is because they’re built with stronger engines and more efficient cooling systems than petrol models, meaning they can run powerful machinery, large appliances, or even multiple devices at once.

This makes this type of generator a go-to choice for commercial and industrial settings, like construction sites, factories, hospitals, or large events, where consistent and reliable power is critical.

2. Great Fuel Efficiency

Diesel generators are known to be more fuel-efficient than their petrol counterparts, especially when running for long hours.

Because they burn less fuel to produce the same amount of electricity, this can ultimately lead to lower running costs over time, which is of course great if you’re using it regularly or for long periods.

3. Stable Power Output

A huge benefit of diesel generators is that they are known for producing a consistent and stable flow of electricity, which is a major advantage if you’re powering sensitive equipment like computers, medical devices, servers, or communications systems.

This makes diesel generators a popular choice for hospitals, data centres, and businesses where even a small power glitch can cause serious problems.

Shop our quality selection of diesel generators here, offering long-lasting and fuel-efficient power for heavy-duty applications and long-term use. Some of our most popular options include the Senci SCD9000Q Canopied Diesel Generator, Stephill SE4500DYES Diesel Generator Electric Start and the Pramac P11000 230V Only Super Silent AMF Diesel Generator.

Potential Drawbacks of Diesel Generator

One potential drawback for some is that diesel generators usually come with a higher upfront price tag compared to petrol models. As well as the cost of the generator itself, diesel fuel, (as touched on further up in the blog), costs more than petrol in the UK, so that’s an important thing to consider also.

Diesel generators are also generally larger and heavier than their petrol counterparts, and because of this, diesel generators often need a more thorough installation, which means moving them isn’t exactly easy.

That said, there are portable diesel generators available that, while still heavier than petrol ones, give you the flexibility to move them between sites, which is a great middle ground for when you really need diesel power but still want some mobility.

The Stephill SSG6000D is a great example of a quality portable diesel generator, providing super silent and versatile power for demanding applications.

So, Which Generator Is Best: Petrol or Diesel​?

As you’ve probably guessed by now, it really comes down to what you need the generator for.

If you’re after something light, portable, and affordable for occasional use, a petrol generator might be all you need. But if you’re powering heavy-duty equipment, running it for long hours, or want something built to last, a diesel generator is probably the smarter choice.

Think about how often you’ll use it, what you’ll be powering, and how much you’re willing to spend – that’ll be sure to point you in the right direction.

Do you have any other questions about generators or require additional advice? Don’t hesitate to get in contact with our experts using this form or via phone at +441639849847.

And if you’re on the hunt for a quality generator, at Generators Direct, we offer a range of single and three-phase generators, power stations and power banks for your specific needs.

All of our products are manufactured, tested and certified to industry standards, and come with a price promise – you won’t find prices cheaper anywhere on the web, but if you do, we’ll match them. In addition to this, all orders come with free mainland UK shipping and after-sales support from our experts.