Dual fuel simply means you buy your gas and your electricity from the same supplier, on one account and usually one bill. The alternative is to take each fuel from whichever company quotes the lowest rate for it, which can mean two suppliers, two accounts and two direct debits. For years a dual fuel discount made the combined deal an easy win, but that discount has shrunk, and the cheapest gas tariff and the cheapest electricity tariff in any given month are not always sold by the same company. This guide shows you how to decide which option is actually cheaper for your home, using your own usage rather than a headline claim.
The short answer. For most households the gap between dual fuel and two separate tariffs is small, often under £30 a year. Dual fuel discounts still exist but are now typically £20 to £60 a year, so the better question is which supplier offers the lowest overall annual cost. Compare the total estimated yearly cost of the best dual fuel deal against the best single-fuel deals added together, then pick whichever number is lower.
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What dual fuel actually means
A dual fuel account bundles your gas and electricity with one supplier. You get one online account, usually one monthly direct debit and one point of contact if something goes wrong. Many suppliers apply a small discount for taking both fuels, built into the unit rates or applied as a fixed annual amount.
With separate suppliers you treat gas and electricity as two distinct products. You might keep electricity with the company that happens to have the keenest electricity tariff, and put gas with a different company offering the cheapest gas. Nothing about the gas in your pipes or the electricity in your sockets changes. The energy is identical regardless of who bills you, because it all comes through the same national networks. The only differences are price, service and admin.
If you are new to how the charges break down, our guide to understanding your energy bill walks through unit rates and standing charges, which are the two numbers that decide the whole comparison.
How big is the dual fuel discount now?
The dual fuel discount was once a headline selling point. Today it is modest. Where it exists at all, it tends to sit somewhere between £20 and £60 a year, and it is often already baked into the advertised tariff rather than shown as a separate line. That matters, because a £25 discount is easily wiped out if the bundled tariff has a slightly higher unit rate than a rival single-fuel deal.
So the discount on its own is rarely the deciding factor. What decides it is the total annual cost. A supplier with no dual fuel discount but lower unit rates can beat a supplier that waves a discount at you while charging more per kilowatt hour. Always compare the full estimated yearly figure, not the size of any sweetener.
One real saving from dual fuel is the standing charge structure. You still pay a separate standing charge for gas and for electricity whether you bundle or split, so dual fuel does not remove a standing charge. If you want to understand why those daily charges are there and why they are so hard to avoid, see our guide to standing charges.
Working out the real cost for your home
The honest answer to which is cheaper is decided by arithmetic, not branding. You need four numbers: your annual gas use in kilowatt hours, your annual electricity use in kilowatt hours, and the unit rate plus standing charge each tariff charges for each fuel. Your last 12 months of bills, or your smart meter data, give you the usage figures.
For each option, the yearly cost of a fuel is: (annual kWh multiplied by the unit rate) plus (365 multiplied by the daily standing charge). Do that for gas and electricity, add them together, and you have the annual cost of that option. Repeat for the best dual fuel deal and for the best separate deals, then compare the totals.
The worked example below uses a typical medium home of roughly 2,700 kWh electricity and 11,500 kWh gas a year, priced at the current Ofgem cap so you can see the method. Slot in your own usage and your own quoted rates to get your answer.
| Charge | Rate used | Annual cost |
|---|---|---|
| Electricity units (2,700 kWh) | 26.32p per kWh | £704.97 |
| Electricity standing charge | 54.83p per day | £208.74 |
| Gas units (11,500 kWh) | 7.97p per kWh | £842.95 |
| Gas standing charge | 29.68p per day | £105.99 |
| Total per year | £1,862.65 |
At 26.32p per kWh electricity and 7.97p per kWh gas, Ofgem price cap 1 October to 31 December 2026 (GB direct-debit average standing charges of 54.83p and 29.68p per day).
That total is the same whether one supplier or two send the bills, because it is built only from rates and usage. A dual fuel discount of, say, £40 a year would shave the bundled total to roughly £1,823. Two separate deals beat that only if their combined rates come out more than £40 a year cheaper. Run both sums and the cheaper option is simply the lower number.
When separate suppliers win
Splitting can pay off in specific situations rather than as a blanket rule.
- One fuel has an unusually good standalone deal. In a competitive month, the cheapest electricity tariff and the cheapest gas tariff are sometimes sold by different companies. If the combined saving from splitting beats any dual fuel discount, splitting wins.
- You want a specialist electricity tariff. If you drive an electric car or run storage heaters, an electricity-only deal with cheap off-peak rates can save far more than any dual fuel discount. See our notes on Economy 7 and night rates and on time-of-use tariffs. Some of the keenest off-peak electricity tariffs are electricity-only by design, so pairing them with a separate cheap gas deal is common.
- You generate your own power. Households with solar and an export tariff sometimes keep electricity with the supplier that pays the best export rate, and buy gas elsewhere.
The trade-off is admin. Two suppliers means two accounts, two direct debits and two sets of customer service. For people who value one simple bill, that friction can outweigh a small saving.
When dual fuel wins
Dual fuel tends to come out ahead, or at least level, in these cases.
- The bundled deal genuinely has the lowest combined rates. Plenty of suppliers price their dual fuel tariff competitively across both fuels, so there is no cheaper split to find.
- You value simplicity. One bill, one account and one renewal date to track is worth something, especially if the alternative saving is only a few pounds a month.
- You want a single fixed deal. Fixing both fuels with one supplier locks your whole energy cost for the term. Our guide to fixed versus variable tariffs covers whether fixing suits you.
Whichever way you lean, the act of comparing is the saving. Households that never switch sit on a default variable tariff, and moving to the right deal, dual fuel or split, can save well over £100 a year compared with doing nothing. Our guide to switching suppliers covers the mechanics, and there is no exit-fee penalty for moving from a standard variable tariff.
The bottom line
For most homes the difference between dual fuel and two separate suppliers is small, frequently under £30 a year, because the dual fuel discount has shrunk to roughly £20 to £60 where it survives. That makes the real decision about total annual cost, not about the bundle itself. Get a comparison both ways: the best dual fuel deal, and the best gas-only and electricity-only deals added together, each shown as an estimated yearly figure for your usage.
Pick the lower number, and then weigh whether any small saving from splitting is worth running two accounts. If you have an electric car, solar panels or storage heaters, check the separate-supplier route carefully, because a specialist electricity tariff can be worth far more than any dual fuel discount. For everyone else, the difference is usually modest, and the bigger win is making sure you are not stranded on a default tariff at all.