How this tool works
The prices come live from the public Octopus Energy Agile tariff feed, which publishes a price for every half hour of the day, region by region.
- Pick your region or enter a postcode and we load today’s prices, plus tomorrow’s once they publish
- The green band on the chart marks the cheapest continuous 3 hour window, which suits most home chargers adding a solid overnight top up
- The dashed line is the standard variable price cap rate, so you can see exactly when smart charging beats doing nothing
New prices for the next day are published around 4pm each afternoon. Before then the chart shows today only.
Why half hourly prices matter for EV drivers
An electric car is usually the biggest single electricity load in the house, and it is also the most flexible: it does not matter when the energy goes in, only that the car is ready when you leave.
On an agile style tariff, prices in the small hours are routinely a third of the evening peak, and on windy nights they can fall below zero. Shifting a 40kWh charge from the evening peak into the cheapest overnight window regularly saves several pounds per charge, which adds up to hundreds of pounds a year for a high mileage driver.
Even without changing tariff, the chart shows the shape of a typical day: expensive from 4pm to 7pm, cheap after midnight. A charger scheduled for the small hours captures most of the benefit on any time of use tariff.
A regular health check keeps charging cheap
Charging cost depends on efficiency as much as price. A car that is down on efficiency because of dragging brakes, poor alignment or worn tyres uses more kWh for the same miles, and every one of those extra kWh costs money.
If your consumption creeps up or your range drops without a change in your driving, it is worth having an EV specialist take a look. The directory lists garages with the training and equipment to work on high voltage systems safely.
Assumptions and accuracy
Prices are the public Octopus Agile import rates for your region, including VAT, refreshed hourly. The 80% charge cost assumes 90% charging efficiency. The comparison line uses the standard variable price cap rate of about 25p per kWh.
These figures are estimates, not a guarantee. Last updated 2026-07-18.