Cost to Charge an EV Overnight UK: 2026 Tariff Maths

Every UK overnight-charging tariff combines a low off-peak rate with a higher peak rate, and a fixed off-peak window when the cheap rate applies. The off-peak rate is what you pay if you put a full charge through the meter between, typically, 11pm and 7am. Outside that window you pay the peak rate — usually somewhere between 24p and 31p per kWh — which is often worse than the Ofgem cap, so you only win if you stay inside the window.

Here's what a full 60kWh charge costs overnight on every major UK EV tariff in April 2026, ranked cheapest first:

Two numbers matter for any overnight-charging calculation: how many kWh you actually push through the meter, and your off-peak rate. The formula is the same one used for any electricity cost — cost (£) = kWh × pence per kWh ÷ 100. Everything below is a refinement of those two figures.

Overnight on a UK EV tariff doesn't mean "at night". It means "inside the off-peak window your supplier defines", and those windows are surprisingly short — most are five or six hours. Plug in before the window opens and you pay peak rates until it starts. Leave it plugged in after the window closes and you keep paying peak rates for whatever's left to add.

Three things shape the windows:

• Length — 5 hours (Octopus Go, British Gas, ScottishPower) to 7 hours (EDF GoElectric). A 7-hour window can comfortably handle a 60kWh charge at 7kW; a 5-hour window cannot (5 × 7 = 35kWh max).
• Start and end time — most run from somewhere between 11pm and 12:30am to somewhere between 5am and 6am. EDF's 11pm–6am is the earliest start and longest run.
• Whether you control scheduling — Intelligent Octopus Go shifts the start automatically based on grid demand (anywhere from 11:30pm), as long as your car or charger is on the supported list. Everything else requires you to schedule the charger yourself.

For a deeper look at how the windows differ by supplier — including PAYG-style tariffs like OVO Charge Anytime that ignore the clock and schedule your charging dynamically — see our best EV tariffs guide.

Battery size and depth-of-charge are the two levers that change your overnight bill the most. The numbers below assume an empty-to-full charge — most overnight sessions add 20–40 kWh in practice, not a full battery, so divide accordingly.

Two caveats worth knowing. First, every figure above is the cost at the meter. AC home charging loses around 10–15% to heat in the charger and onboard converter, so the energy that actually reaches the battery is slightly less than the meter reading suggests. For cost-per-mile maths this is already baked into the "4 miles per kWh" assumption.

Second, real-world charging sessions rarely go from 0% to 100%. Most overnight charges top up from 30–50% to 80–90%, which means you're putting 20–40 kWh through the meter, not 60–80. A typical commuter charging an Octopus IOG car from 50% to 90% on a 77kWh battery pays roughly £1.54 for the session.

If you want to budget what overnight charging adds to your monthly bill, work backwards from miles driven rather than full battery charges. UK average efficiency for current EVs is around 3.5–4.5 miles per kWh combined; we'll use 4.0 mi/kWh for round numbers.

The high-mileage scenarios are where smart tariffs earn their keep. A 150-mile-per-day driver on Intelligent Octopus Go pays about £56 a month for fuel; the same driver charging on the cap would pay £311. Annualised that's a £3,065 difference — more than enough to clear the cost of a new home EV charger in the first year of ownership.

From 1 April 2026 the Ofgem default cap stands at 27.7p/kWh. Charging an EV on that rate is roughly equivalent to filling a 40mpg petrol car at £1.27 per litre in fuel-cost terms — about the same as today's petrol pump. Charging the same car overnight on Intelligent Octopus Go at 5p/kWh is closer to 23p per litre.

The percentage savings come out as:

• Intelligent Octopus Go vs cap: 82% cheaper per kWh (87% at the cheapest regional rate).
• EDF GoElectric vs cap: 75% cheaper.
• E.ON Next Drive / British Gas EV Power vs cap: 69% cheaper.
• ScottishPower EV Saver vs cap: 68% cheaper.

None of these tariffs is free — you still pay a peak rate (usually 24–31p/kWh) for any electricity used outside the off-peak window. If your household uses more than about 5,000 kWh/year of non-EV electricity outside the window, the higher peak rate can eat back into the savings. Most single-EV households with sensible appliance scheduling don't hit that threshold.

The cheap rate is conditional. To pay 5p or 7p per kWh instead of 27p, three things need to be in place — and any one of them missing means you pay peak rates for the session.

1. You need a half-hourly smart meter (SMETS2 or compliant SMETS1). All UK EV tariffs require it. Suppliers can usually upgrade you for free, but the appointment can take 2–6 weeks. Without a smart meter, you cannot move onto an EV tariff at all.
2. You need to be on the EV tariff itself. Switching from a standard variable tariff to Intelligent Octopus Go, EDF GoElectric, or similar is a free supplier change but takes 14–21 days to complete. Until the switch lands, you're still paying the cap rate even if your charger and car are configured perfectly.
3. Charging has to happen inside the window. This is where it most often goes wrong. The supplier doesn't care whether you forgot to plug in, slept through the start time, or set the schedule wrong — anything outside the window is billed at peak. Set the charger schedule to match your tariff's window exactly (or, on Intelligent Octopus Go, let Octopus schedule it for you via the API).

If you have a smart-charging EV on the IOG compatible list, you can let the car and supplier handle scheduling between them. Otherwise, pick a smart charger that integrates with your tariff — see our best charger for IOG guide for what works with which tariff.

A 60kWh charge at a 7kW home charger takes about 8.5 hours. The longest UK off-peak window is EDF GoElectric's 7 hours; most are 5 or 6. So if you're charging an empty battery you will probably finish in peak hours, at peak rates.

Three practical responses:

• Top up nightly rather than charging empty-to-full. A 5-hour Octopus Go window handles 35 kWh — about 140 miles of range at 4 mi/kWh, which covers most commute days twice over.
• Cap the session at the window end. Most smart chargers let you set both a start time and an end time. Setting the end time to match your tariff's window means the charger stops the moment peak rates kick in.
• Use the Intelligent Octopus Go 6-hour cap. On IOG, Octopus guarantees up to 6 hours of off-peak charging per night even if the published window is shorter, as long as you've set the target time in the Octopus app.

Charging an EV overnight in the UK in 2026 costs as little as £2 for a full 60kWh battery on Intelligent Octopus Go, or as much as £17 on the Ofgem default cap — a 75-85% difference driven entirely by which tariff your meter is on. The price of the charger, the speed of the charger, and even the size of the battery matter far less than that single decision. Get the right tariff, schedule the charge inside the off-peak window, and the per-mile cost of running an EV drops to roughly 1–2p — territory no petrol car can reach.