What an electric mile actually costs in 2026

Ask what a petrol mile costs and there is one answer within a few pence, because every forecourt in the country charges about the same. Ask what an electric mile costs and the honest answer is "where did you charge?" The same car, on the same road, can cost three times as much per mile depending on which socket it was plugged into the night before. That is the whole reason an electric log needs more than a single fuel price.

Three prices, not one

From 1 October to 31 December 2026 the Ofgem price cap puts a typical direct-debit electricity unit at 26.32p per kWh, with a standing charge of 54.83p a day. That is the price of a home charge on a standard tariff, and the standing charge is paid whether you charge the car or not, so the marginal cost of a mile is the unit rate alone.

Most electric car owners are not on a standard tariff. The big suppliers sell EV tariffs with a cheap window overnight, and an owner who sets the car to charge inside that window pays a fraction of the cap rate for most of their driving. The tariff pages publish the rate and the hours; the only number that matters is the one on yours.

Public charging is the other end. Zapmap's price index for September 2026 puts the weighted average pay-as-you-go price at 54p per kWh on standard chargers and 79p per kWh on rapid and ultra-rapid units, with the ten biggest rapid networks ranging from 59p to 92p.

What that does to a mile

Take a family-sized electric car returning 3.5 miles per kWh, which is a fair real-world figure for mixed driving outside the coldest months. A kWh moves it 3.5 miles, so the cost of a mile is the price of a kWh divided by 3.5:

For comparison, a petrol car at 45 mpg and 145p a litre costs about 14.6p a mile in fuel. An electric car charged at home on the cap rate undercuts it by half. The same car on rapid chargers costs more than the petrol one. Both statements are true at once, which is why "electric is cheaper" and "electric is a rip-off" are both common and both incomplete.

Winter matters too. Cold batteries and cabin heating can push 3.5 miles per kWh down towards 2.5, and every figure in the table rises by 40% with it. A log that measures your real efficiency month by month shows this happening; a brochure figure never will.

Knowing which price your car runs on

The practical problem is that nobody charges in one place. A week might be five nights at home, one top-up at work and one rapid charge on a long trip. Your real cost per mile is a blend, and the blend changes with the week.

Milometry's approach is to log each charge with where it happened, keep a tariff book with your home, off-peak, work and public rates so a charge prices itself from the kWh, and measure your efficiency from the battery readings between charges. The cost of each journey comes from that measured efficiency and the price your car is usually charged at, which is your cheapest home rate when you have one. A public rapid charge is counted in what you spent, but it is never the rate a year's driving is costed at, because one motorway stop is not what the car normally costs you.

That gives a figure you can defend: the real cost per mile of your car, this winter, charged the way you actually charge it. For a business mile it also makes the comparison honest. HMRC's approved mileage rate is the same for an electric car as for a petrol one, 55p for the first 10,000 business miles, so the gap between what the mile costs you and what the rate pays is a number worth knowing.

CO₂, since people ask

An electric car has no tailpipe, but the electricity came from somewhere. The UK Government's 2025 conversion factors put grid electricity at about 0.177 kg of CO₂e per kWh, so our 3.5 miles per kWh car emits about 50 g per mile at the grid average, against roughly 230 g per mile for the 45 mpg petrol car. Milometry counts electricity at that generation rate rather than reporting zero, because zero is not the honest number either.

These figures are estimates to help you keep a record, not tax advice. Check your own tariff for the rate that applies to you.

Sources

• Energy price cap unit rates and standing charges, Ofgem. The 1 October to 31 December 2026 figures.
• UK EV charging price index, Zapmap. The September 2026 weighted averages for standard and rapid charging.
• Intelligent Octopus Go, Octopus Energy. An example of an EV tariff with an overnight window; the rate is on the page.
• Greenhouse gas reporting: conversion factors 2025, DESNZ. The electricity generation factor.
• Expenses and benefits: business travel mileage, rules for tax, GOV.UK. The approved mileage rate applies to electric cars.