Charging an electric car at home can be considerably cheaper than filling a petrol or diesel car, particularly if you have access to an overnight EV electricity tariff. But the amount you actually pay depends on your tariff, the car’s efficiency and how much electricity you need to put back into the battery.
As of October 2026, the average electricity unit rate under the Ofgem price cap is 26.32p per kWh for customers paying by Direct Debit in Great Britain. Dedicated smart EV tariffs can offer much lower off-peak prices, with some advertised from 7.6p per kWh. Check the rate available for your address before switching.
For an EV averaging 3.5 miles per kWh, those rates work out at approximately 8.3p per mile on a standard tariff or 2.4p per mile on the illustrative smart rate, allowing for some energy lost during home charging.
The difference is substantial, but there are a few things worth understanding before comparing the cost with petrol, diesel or public charging.
Is Home Charging Cheaper Than Petrol or Diesel?
For most drivers who can charge regularly at home, the answer is yes.
Electricity bought overnight on a dedicated EV tariff is usually much cheaper per mile than petrol or diesel. Charging on a standard domestic electricity tariff can also offer savings, although the gap is smaller.
Fuel prices and vehicle efficiency make a big difference. According to RAC Fuel Watch, UK petrol averaged approximately £1.75 per litre in early October 2026, while diesel reached around £2 per litre.
At those prices, a petrol car achieving 45mpg costs approximately 17.7p per mile in fuel. A diesel car achieving 50mpg costs around 18.2p per mile. These examples use imperial UK gallons.
An EV charging at the illustrative overnight rate of 7.6p/kWh would cost around 2.4p per mile at 3.5mi/kWh, including our allowance for home-charging overhead.
That does not mean every EV is cheaper to own overall. Purchase price, insurance, depreciation, servicing and the cost of installing a home charger also matter. But for drivers able to access inexpensive home electricity, energy costs remain one of the strongest arguments for switching.
Understanding EV Battery Size and Charging Costs
An EV battery serves a similar purpose to the fuel tank in a petrol or diesel car. Instead of storing litres of fuel, it stores electrical energy measured in kilowatt-hours (kWh).
Battery sizes vary considerably between models. As a simple guide:
- A smaller electric car might have a battery of around 40kWh.
- A medium-sized family EV might have approximately 60kWh.
- A larger or long-range EV could have a battery of 80kWh or more.
A larger battery can store more energy, but range also depends on the vehicle’s efficiency, driving speed, temperature and conditions.
The basic calculation for charging cost is:
Electricity drawn from the mains (kWh) × electricity unit rate (£/kWh) = charging cost
There is one important detail: the amount of electricity delivered through your home charger is not always the same as the energy stored in the vehicle’s battery.
Some electricity is used by the charging equipment and the vehicle itself, while some is lost as heat. The exact amount varies with the car, charger, charging power and conditions.
For the worked examples below, we have assumed that charging draws 10% more electricity from the mains than the energy added to the battery. This is an illustrative assumption rather than a fixed efficiency figure for every EV.
How Much Does a Full EV Charge Cost?
The following comparison uses two October 2026 electricity prices:
- Standard tariff: 26.32p/kWh, the Ofgem average electricity unit rate for default-tariff Direct Debit customers in Great Britain.
- Smart EV tariff: 7.6p/kWh, an illustrative advertised smart-charging rate reported for Intelligent Octopus Go in October 2026. The supplier’s current displayed quote and regional terms should be checked, as published prices may differ.
| Energy added to battery | Standard tariff (26.32p/kWh) | Smart EV tariff (7.6p/kWh) |
|---|---|---|
| 40kWh | £11.58 | £3.34 |
| 60kWh | £17.37 | £5.02 |
| 80kWh | £23.16 | £6.69 |
The difference becomes particularly noticeable with larger batteries. Adding 80kWh of energy would cost approximately £23.16 on the example standard tariff, compared with £6.69 at the smart rate.
However, very few EV owners regularly charge from completely empty to full.
Most drivers replace the energy they have used rather than paying for a full battery charge every night.
What About a Normal Overnight Top-Up?
Imagine a car with a usable battery capacity of 60kWh arriving home at 20% charge.
Charging it to 80% adds approximately 36kWh to the battery. Assuming the same 10% additional electricity consumption, the home charger would draw around 39.6kWh from the mains.
That would cost approximately:
- £10.42 on the example standard tariff.
- £3.01 on the example smart EV tariff.
A smaller daily top-up would cost less again.
Battery size alone therefore does not determine your weekly charging bill. The number of miles driven, the car’s efficiency and the electricity tariff are usually more useful measures of running costs.
What Does EV Charging Cost Per Mile?
Cost per mile is one of the simplest ways to compare electric cars with petrol and diesel vehicles.
Most EVs display efficiency in miles per kWh, usually shortened to mi/kWh. The higher this number, the further the car travels using the same amount of electricity.
Assuming an EV averages 3.5mi/kWh, with 10% additional energy drawn during charging:
| Energy source | Approximate cost per mile |
|---|---|
| Home charging at 26.32p/kWh | 8.3p |
| Smart home charging at 7.6p/kWh | 2.4p |
| Petrol at £1.75/litre and 45mpg | 17.7p |
| Diesel at £2/litre and 50mpg | 18.2p |
For a driver covering 10,000 miles annually, the electric car in this example would cost approximately £827 in electricity on the standard tariff or £239 using the lower smart rate throughout.
That compares with roughly £1,768 in fuel for the example petrol car.
These figures cover electricity or fuel only, not total ownership costs.
Seasonal efficiency also matters. An EV that achieves 3.8mi/kWh during summer might return noticeably less during winter, particularly on short journeys or at motorway speeds.
Our Peugeot E-3008 long-term ownership update explores how everyday use and seasonal conditions affect real-world efficiency.
Standard Electricity Tariffs vs Smart EV Tariffs
The electricity tariff you choose can make a bigger difference to charging costs than the size of the car.
A standard single-rate tariff charges the same unit price throughout the day. Time-of-use tariffs, including specialist EV tariffs, offer cheaper electricity during particular periods.
Intelligent Octopus Go is one example. It works with compatible vehicles or charging equipment and allows drivers to set charging requirements through the supplier’s app.
The system then schedules charging around eligible cheaper periods.
The tariff also offers six hours of discounted electricity for the home between 11:30pm and 5:30am, with eligible smart charging potentially scheduled outside that window under the supplier’s conditions.
Other energy suppliers offer their own EV tariffs, with different prices, charging windows and eligibility requirements.
Are Smart EV Tariffs Always Worth It?
Not automatically.
An EV tariff may have a higher daytime electricity price or a different standing charge compared with your existing deal.
Before switching, compare the total expected cost of electricity for your home, not simply the cheapest advertised charging rate.
Consider how much electricity you use during the day, how regularly you need to charge and whether your car or charger meets the tariff’s compatibility requirements.
It is also important to check when discounted electricity applies. Charging outside the agreed off-peak or smart-charging arrangements may be charged at the normal daytime rate.
Drivers using a compatible smart charging setup can often save significantly, but the actual benefit depends on their household usage and charging habits.
If you already use a smart tariff, our guide to auditing an EV smart charging electricity bill explains how to check your charging sessions against your supplier’s half-hourly electricity data.
Can You Charge an EV From a Three-Pin Plug?
It is possible to charge some electric cars using manufacturer-approved portable charging equipment connected to a suitable domestic socket.
However, a normal three-pin household socket should generally be treated as an occasional or emergency charging option rather than a routine substitute for a dedicated EV charger.
Charging an electric vehicle places a sustained electrical load on the socket and wiring for several hours.
Electrical Safety First warns that ordinary sockets and wiring may not be suitable for extended EV charging loads.
For regular charging, a properly installed dedicated home charge point is the recommended option.
If portable charging is necessary, follow the vehicle and charging-equipment manufacturers’ instructions and have the electrical installation assessed by a suitably qualified electrician. Avoid extension leads and unsuitable adaptors.
A dedicated 7kW home charger can also charge substantially faster than a typical portable three-pin arrangement, provided the car supports that charging power.
Home charger installation introduces an upfront cost, so this should be considered alongside the potential savings from cheaper electricity.
Home Charging vs Public Charging
Public charging remains essential for longer journeys, drivers without suitable home charging and anyone needing to recharge away from home.
But public charging can be substantially more expensive.
According to the Zapmap Charging Price Index, the weighted average UK pay-as-you-go prices for September 2026 were:
- 54p/kWh for standard and standard-plus public chargers.
- 79p/kWh for rapid and ultra-rapid public chargers.
Those prices are far higher than the example 7.6p/kWh overnight home rate.
At 3.5mi/kWh, a public charging price of 79p/kWh works out at approximately 22.6p per mile based on electricity delivered by the charger, before considering any additional vehicle-side losses or fees.
Public charging prices vary between networks and locations. Subscriptions, roaming services and promotional tariffs may offer lower rates than standard pay-as-you-go prices.
For drivers who complete most of their charging at home, occasional public charging is unlikely to remove the overall cost advantage. However, someone relying heavily on public rapid chargers may face a very different running-cost calculation.
The important comparison is therefore not simply electric versus petrol or diesel. It is where you charge, what you pay and how efficiently your vehicle uses that electricity.
Three Simple Ways to Reduce EV Charging Costs
There are several practical ways to keep electricity costs under control without making everyday ownership complicated.
1. Use Cheaper Charging Periods
If your home and vehicle are suitable, a dedicated EV tariff can provide a much lower unit rate during eligible charging periods.
Make sure the vehicle or charging app is configured correctly and check that your electricity supplier has billed the charging sessions at the expected rate.
2. Precondition Your Car While Plugged In
During colder weather, warming the cabin before leaving can reduce the energy required from the battery once you start driving.
This can be particularly useful on shorter winter journeys, although preconditioning itself consumes electricity and its benefit depends on the vehicle and conditions.
Battery preconditioning for rapid charging is a related but different process. Our guide to why EV battery preconditioning matters explains the distinction.
3. Pay Attention to Efficiency, Not Just Battery Percentage
An EV’s estimated range changes with temperature, speed, driving style and recent energy consumption.
Watching your average miles per kWh can give you a clearer picture of running costs than simply relying on the dashboard’s estimated remaining range.
Our EV Guess-o-Meter ownership feature explains why those range estimates can change so noticeably between journeys.
Tech Torque Verdict
Charging an EV at home remains one of the most affordable ways to cover everyday mileage, especially for drivers with access to a suitable overnight electricity tariff.
The difference between a standard domestic rate and a dedicated EV tariff can be substantial. In our October 2026 examples, adding 60kWh of energy to a battery costs approximately £17.37 on the standard tariff and £5.02 at the example smart rate.
But the cheapest advertised unit rate does not tell the whole story. Charging losses, vehicle efficiency, electricity used elsewhere in the home and the wider tariff conditions all affect the real cost.
Drivers relying on public rapid charging will face considerably higher energy prices, while households without off-street parking may have fewer opportunities to benefit from low-cost home charging.
For those able to install a dedicated charger and use a competitive overnight tariff, however, the financial case remains compelling.
The biggest advantage is not simply owning an electric car with a large battery. It is being able to charge that car efficiently, conveniently and at the right electricity price.
Price reference: 10 October 2026. Electricity and fuel prices are subject to change. The examples use published UK reference rates and clearly stated assumptions rather than guaranteed costs for every household or vehicle.
