How to choose the best energy supplier

Sticking with your current provider's variable tariff could be costing you. Use our advice to find the best energy firm for you.

There are around 20 energy firms to choose from at the moment. This is down from more than 50 at the end of 2020.

Switching could save you money, especially if you're currently on a supplier's price cap variable rate. We've found fixed deals that can save save around £200 compared to the price cap variable rates. And our research reveals big differences between customers' experiences with the best and worst energy providers. 

Keep scrolling for advice on how to find the best energy firm for you. Or see the best energy companies for 2026.

What to think about when choosing an energy supplier

• Quality of service: If you've got questions about your energy service, or something goes wrong, you want to know that your supplier will deal well with your queries or concerns. Our annual energy supplier assessments can help you choose a provider that will deliver.  
• Costs: Tariff prices remain high, so choosing a supplier that offers good value is likely to be many people's top priority. You'll need to factor in unit pricing, standing charges, and any fees.  
• Smart functionality: If you've got, or are planning to get, a smart meter, you may want to choose a supplier that offers innovative smart functionality and products. 
• Innovative tariffs: If you own an EV, or mainly use energy at off-peak times of day, you may be able to save money with a smart time-of-use tariff. 
• Bundled options: Some suppliers let you bundle in your energy with telecoms or boiler cover, which could save money or hassle compared with buying services separately. 
• Sustainability: We've analysed energy companies eco-credentials and made the greenest suppliers Which? Eco Providers. 

See the latest deals on the market: How to get the best energy deal

Are bigger energy suppliers better?

In January 2025, Octopus Energy announced that it was the biggest energy supplier in the UK. As of December 2025, it serves around 7.8m customers – or 1 in 4 households.

Four longstanding energy firms – British Gas, EDF Energy, E.ON Next and Scottish Power – make up a large portion of the rest of the energy market. Ovo has also grown considerably, after taking on SSE's customers in 2020. 

What do customers think of Octopus, British Gas, Ovo and other big suppliers?

Biggest isn't necessarily best, according to our research. While Octopus Energy is a Which? Recommended Provider again in 2026, several other big-name brands languish near the bottom of our results table.

Our energy company results give you a unique insight into what your fellow customers really think of their energy suppliers. Plus, we've gone behind-the-scenes to check if their policies and practices are in the best interests of customers.

Use the results of our latest energy survey, plus our expert advice, to cut through the marketing jargon and money-saving claims to find the best energy suppliers.

Should I choose a small energy supplier?

Several smaller energy companies, including 100Green, E (Gas & Electricity) and Good Energy, received high customer scores in our latest satisfaction survey. Some companies are too small for us to get enough responses to rate them in our annual assessments, but we've previously seen small firms that excel when we've had enough customers in our survey to rate them for the first time. 

However, choosing a very small company does increase the risk that it may go bust. Small supplier Tomato Energy, for example, ceased trading in November 2025 after finding its rapid growth unsustainable. 

Even larger companies aren't immune from this risk, though. And if a company you have a tariff with does go bust, regulator Ofgem has processes in place to transfer your account to a new supplier and ensure you won't be cut off.  

Looking for energy firms in Northern Ireland? Head to our guide to Northern Ireland electricity and gas companies.

Which is the cheapest energy supplier?

There's no categorical answer to this. There are around 20 domestic energy suppliers in the UK, each offering a range of tariffs. These tariffs are updated on a regular basis, usually in line with Ofgem's three-monthly energy price cap changes. 

What this means is that there is no overall cheapest supplier; it's all about the specific tariff. 

When you're choosing the cheapest tariff for your household, you'll need to consider:

• Tariff rates. A key choice you'll need to make is between a fixed or variable tariff. The majority of variable tariffs are closely aligned with the levels of the energy price cap. These are typically some of the most expensive options on the market, especially if you're on your supplier's default variable tariff. Fixed tariffs set your energy unit rates a year or more in advance, and our regular analysis of the cheapest energy deals has found that most fixed tariffs are cheaper than the corresponding price cap tariff. The downside of fixed tariffs is that if you want to leave your contract early, you'll usually (though not always) have to pay a hefty exit fee. 
• How much energy you use. Energy tariff costs are broken down into unit rates for the gas and electricity you actually use, and daily standing charges which are fixed regardless of how much energy you use. Providers can choose how they weight their tariffs; some tariffs have higher standing charges but lower unit rates, and vice versa. If you're a low energy user, you're likely to be better off with a tariff that has lower standing charges as a proportion of the total bill. Meanwhile higher energy users may be better off with a tariff that has higher standing charges and lower unit rates. 
• When you use your energy. If you have an electric vehicle that you mainly charge overnight, or if you're able to carry out energy intensive tasks at times of day or week when national demand for energy is lower, you may be able to benefit from smart time-of-use tariffs that charge less for energy used at off-peak times. You'll need a smart meter to take advantage of this type of tariff. 

There are some suppliers that feature frequently in our regular round up of the cheapest fixed energy deals, including Ecotricity, EDF Energy, E.ON Next, Fuse, Outfox Energy, and So Energy. So if you're looking for a cheap supplier, these may be a good place to start. 

Or if you're looking for a balance of price and quality of service, Which? Recommended Providers Octopus Energy and Sainsbury's Energy usually offer fixed tariffs that are substantially cheaper than the price cap. 

What if I've got a prepayment meter?

Several energy suppliers focus on customers with prepayment energy meters, including Which? Recommended Provider E (Gas & Electricity), as well as Utilita. 

If you have a smart prepayment meter you can top-up using your provider's app, your online account or by phone.

Pre-payment customers may have less choice of tariffs than those who pay by monthly direct debit. For example, we've only found one provider – EDF Energy – that offers fixed tariffs for prepayment customers. 

If you have a PAYG energy meter, or are considering one, read our advice guide: Is a prepayment energy meter right for you?

What 'smart' technology is available?

All energy firms are installing smart meters. These replace your existing gas and electricity meters and use a wireless data network to send your usage figures straight to your energy supplier. More than 70% of UK homes now have smart meters installed. 

Smart meters usually come with an in-home digital display. The makes and models of these vary between suppliers but they have the same basic functionality of showing you your energy use and spend in near real-time.

A few monitors are now wi-fi-enabled, including the latest ones from Ovo and Utilita. This means meter readings can be collected in real-time and it's easier to update your monitor or diagnose any problems with it.

Octopus Energy offers the 'Octopus Home Mini' which uses wi-fi to transmit your usage and costs to your app and online account in a few seconds. As of January 2026, there's a waiting list to get a Home Mini. 

Most companies also let you see your smart meter data in an app or online account though their exact functions vary. 

Find out more about smart gas meters and smart electricity meters: What is a smart meter?

Smart energy apps

Most energy suppliers offer their own mobile apps through which you can monitor your energy usage.

These apps typically include the ability to:

• see historical usage, usually split by fuel and day/week/month depending on how often your smart meter sends data
• view your bills
• view account details and payment information
• send meter readings
• top up prepayment meters.

Digital-first suppliers

Some newer energy firms claim to be digitally focused and pride themselves on a slick online service, apps and user-friendly websites. 

When new supplier, Fuse Energy, launched it was an app-only provider. You can now sign up and manage your account online, but you'll get the best experience through its app. 

Meanwhile E (Gas & Electricity) and Utilita's customers with smart prepayment meters can top up via their apps. 

Several firms, including Scottish Power and Utilita, show customers how their electricity use and spend is split between different types of home appliances in their apps or online account.

Smart home products

Several suppliers sell smart-home products such as smart thermostats too, or include them free when you sign up to certain tariffs. They include:

• British Gas – sells smart products from its Hive brands, including smart thermostats, smart plugs and smart light bulbs.
• Ovo Energy – currently offers the Tado smart thermostat.
• Scottish Power – also sells Tado smart thermostats as well as smart radiator thermostats, which let you control the heat in each room separately, and smart hot water controls.  

To learn more about the power of smart home technology, check our guides to outdoor security cameras, indoor security cameras, smart thermostats and smart radiator valves.

Should I consider a smart tariff?

The majority of traditional tariffs are structured as:

• a daily standing charge
• a fixed rate for each unit of energy you use (unit rate). 

The charges and rates are different for gas and electricity. But there are different types of tariff if you look for them, many enabled by smart meters.

Read more about different types of energy tariff explained.

Smart tariffs 

These require you to have a smart meter installed. Often they give lower prices for electricity used at specific times of day. For example:

• E.ON Next's 'Next Smart Saver' tariff offers cheaper electricity rates during off-peak hours, and higher rates during peak hours (4pm-7pm). 
• Octopus Energy's Intelligent Octopus tariff has six hours of cheaper electricity overnight. Its Agile Octopus tariff tracks half-hourly wholesale prices and updates its rates daily. 

The government expects smart tariffs to become more widespread as smart meters are further rolled out, more people have electric vehicles and electricity demand increases.

Find out more: Time of use tariffs explained

Electric vehicle tariffs

Most electric vehicle (EV) tariffs require you to have a smart meter, as well as an electric vehicle charger. Customers can get cheaper electricity for a number of hours – usually overnight – to help charge their car's battery for less.

A growing number of energy suppliers sell EV tariffs, including British Gas, Ecotricity, EDF Energy, E.ON Next, Fuse, Good Energy, Octopus Energy, Ovo Energy Scottish Power, So Energy, and Utility Warehouse. 

Smart export guarantee tariffs

Smart Export Guarantee (SEG) tariffs reward customers who generate their own energy and export any energy they don't use back to the national grid. The most common generation technology is solar panels, but you're also eligible if you generate energy from wind, hydro, micro combined heat and power (CHP), and anaerobic digestion. 

You'll need a meter that can transmit half-hourly readings. For most people, this will mean a smart meter, though there are some other advanced meter types that can transmit half-hourly readings. 

Find out more: Smart Export Guarantee explained

Is it worth bundling my energy with broadband or boiler cover?

Some firms bundle multiple home services together in one monthly bill. Utility Warehouse was the first firm to do this.

Utility Warehouse provides energy, broadband and mobile in one package. You can select one or both extra services to bundle with your energy. The firm says this allows customers to 'get on with the things that really matter in life.' During our latest energy supplier survey, we heard from several Utility Warehouse customers who appreciated the system.

Find out what customers think of Utility Warehouse broadband.

Boiler cover and insurance

Several larger energy companies sell boiler cover that often comes with call-out repair services if yours breaks. Often they're a partnership with an insurance provider:

• British Gas's HomeCare packages include boiler servicing and repairs, depending on the package. It also sells appliance and home electrics cover.
• EDF Energy sells boiler maintenance and insurance plans from Domestic & General.
• E.ON Next sells boiler cover, central heating cover, electrics and plumbing cover from HomeServe.
• Ovo Energy's boiler cover includes servicing and breakdowns.
• Scottish Power sells boiler cover from Domestic & General.

To save money and avoid being charged over the odds, explore our guide to how to choose the best boiler cover.

Should I choose a renewable energy company?

Several energy companies, and more tariffs, are branded as ‘green’. But there’s no set definition of what ‘green’ means, so it’s worth checking before you sign up to make sure you’re getting what you expect.

We asked energy companies for information on a range of sustainability criteria in August 2024. Then we awarded them points based on their responses and information published on their websites. 

As a result, we named 100Green, Ecotricity, Good Energy and Octopus Energy as Eco Providers for 2025. 

Our scoring looked at:

• Buying and selling renewable power
• Generating renewable power
• Fossil fuel links
• Green gas
• Time of use and Smart Export Guarantee tariffs, plus EV tariffs. 
• Low carbon installations
• Greenhouse gas emissions.

Find out more about our scoring for the Eco Providers for energy 2025.

Fully 'green' energy suppliers

Ecotricity was the first company to offer ‘green electricity’ made from renewable sources. It sits alongside 100Green and Good Energy as one of the most longstanding renewable energy companies.

All three firms only sell tariffs backed by 100% renewable electricity and supply a proportion of ‘green gas’ (from biomethane). Ecotricity uses money from its customers' bills to fund new renewable generation. Good Energy, meanwhile, buys its electricity from more than 1,700 independent renewable generators. Which? Recommended Provider 100Green is the only company to sell 100% green gas.  

Other energy suppliers selling 100% renewable electricity tariffs (alongside standard tariffs) include E.ON Next, Octopus Energy, Outfox the Market, Ovo Energy and So Energy. 

You'll also find other energy firms selling 'zero carbon' tariffs. These include EDF Energy. This usually means their electricity comes from either renewables or nuclear power. 

Additionally, some suppliers sell a proportion of green gas (usually from biomethane) and invest in carbon reduction or carbon offset schemes for their gas tariffs.

Find out more with our guide: What's the difference between green energy suppliers?