EV Savings Calculator

EV Savings Calculator

Use this EV savings calculator to compare the annual running cost of a petrol or diesel car with an electric car.

Enter your annual mileage, fuel economy, petrol or diesel price, EV charging rate and electric car efficiency to compare the cost per mile and yearly running cost.

You can also include the new 2028 electric vehicle mileage charge to see how that could change the comparison.

Compare Petrol vs Electric Car Running Costs

Use the calculator below to compare your current petrol or diesel car with an electric car.

The EV figure is based on the electricity price you actually expect to pay for charging, so you can compare anything from a normal household electricity tariff to a cheap overnight EV tariff.

EV Charging Time and Cost Calculator

How long does it take to charge an electric car?

The answer depends on the size of the battery, how much charge you need to add and the power available from the charger.

Use this EV charging calculator to estimate:

• how many kWh you need to add
• how long charging could take
• how much the charge will cost
• how many miles of driving that energy could provide

You can compare 3 kW charging and a typical 7 kW home EV charger, or enter your own charging speed.

The charging time is an estimate. Your car can only charge at the maximum rate it supports, and charging speeds can vary during a session.

This becomes especially important with rapid public charging, where a charger may be capable of much more power than your car can actually accept.

EV Tariff Break-Even Calculator

Is a cheap overnight EV tariff actually cheaper for your whole household? Enter the tariffs available to you and compare annual electricity costs.

These are illustrative starting rates, not live tariff quotes. Enter your own electricity prices, household consumption and EV mileage.

How Much Does It Cost to Charge an Electric Car?

The cost of charging an EV depends mainly on two things:

How much electricity you use and how much you pay per kWh.

For example, an electric car averaging 4 miles per kWh would cost:

• 2p per mile at 8p/kWh
• 4p per mile at 16p/kWh
• 7p per mile at 28p/kWh

That is why the electricity tariff you use can make such a big difference to EV running costs.

If your car averages 4 mi/kWh, every 1 kWh of electricity gives you roughly 4 miles of driving.

Real-world efficiency will vary with the car, speed, journey type, weather and temperature.

Home EV Charging and Cheap Overnight Tariffs

For many EV drivers, home charging is where the lowest charging costs are available.

Time-of-use electricity tariffs can offer much cheaper electricity during certain hours, allowing you to charge the car overnight instead of paying the normal daytime rate.

This can reduce the cost per mile considerably.

I track and write about several Octopus smart tariffs, including:

• Intelligent Octopus Go
• Octopus Go

Intelligent Octopus Go uses smart charging to schedule the car, while Octopus Go provides a fixed cheaper charging period.

Tariff prices and rules change, so check the individual tariff pages for the latest rates and charging times.

Need a home EV charger?

If you’re looking to install a home EV charger, Octopus Energy currently offers a £25 referral reward after an eligible charger installation.

Register through my referral link before requesting your quote and use the same email address throughout the process.

Get £25 with an Octopus EV charger

I also receive a £25 gift card if your installation qualifies, which helps support Energy Stats UK.

Charging an EV Away From Home

You will not always be able to charge at home.

Public EV charging is useful for longer journeys, holidays and times when you simply need more range while you are out.

Public charging prices can vary considerably between charging networks and locations, and rapid charging will normally cost more than cheap overnight charging at home.

This is why I treat public charging and home charging as two different parts of EV ownership rather than assuming every mile costs the same amount.

Find Public EV Chargers with Octopus Electroverse

I use Octopus Electroverse when I need to charge away from home.

Electroverse lets you find public EV chargers, check charging prices and availability, plan journeys and access chargers across a large number of charging networks through one account.

If you sign up using my referral link, we currently receive £5 of charging credit each once the qualifying referral conditions have been met.

New to Octopus Electroverse?

Use my referral link to sign up. After the qualifying charging requirements are completed, we currently receive £5 of Electroverse charging credit each.

Sign up to Octopus Electroverse

Referral offers can change, so check the Electroverse sign-up page and terms for the current offer.

What Is the 2028 Electric Vehicle Mileage Charge?

From 1 April 2028, the UK government is introducing Electric Vehicle Excise Duty, or eVED.

Fully electric cars will initially pay 3p per mile, in addition to the normal Vehicle Excise Duty system.

That means an electric car travelling 8,000 miles a year would initially pay:

8,000 miles × 3p = £240 per year

The EV savings calculator above includes an optional switch so you can see how the new mileage charge could affect your own running-cost comparison.

The initial eVED rate is due to increase with inflation from 2029/30.

EV Cost Per Mile: What Should You Compare?

When comparing an electric car with petrol or diesel, it is better to compare the cost of actually driving a mile rather than simply looking at the price of electricity or fuel.

For a petrol or diesel car, that depends on:

• fuel price per litre
• your real-world mpg
• annual mileage

For an electric car, it depends on:

• electricity price per kWh
• real-world miles per kWh
• annual mileage
• where and when you charge
• from April 2028, the eVED mileage charge

The cheapest EV charging can be very cheap per mile, but someone relying heavily on rapid public charging will get a very different result.

That is why the calculators on this page let you enter your own figures rather than assuming one fixed EV running cost.