A public EV charging price comparison is easy to get wrong from the driver’s seat. You see a headline rate, tap a card, charge just enough to get home and carry on. But the number that matters is not the advertised pence per kWh in isolation. It is what that session added to your actual running cost, including fees, subscription commitments and the miles you got from it.
Public charging is often the least tidy part of an EV budget. Prices vary by network, site, speed, payment method and time. A cheap-looking charger can become expensive if it involves a monthly membership you barely use. A high-rate rapid charger may still be the sensible choice when it prevents a long detour or gets a working day back on track. Honest comparison starts by separating the charging decision from the marketing figure.
What to compare in public EV charging prices
Start with the unit rate in pence per kWh, but do not stop there. This is the energy price shown on the charger or in the app, and it is the cleanest starting point when comparing two chargers on the same terms. If one network charges 59p per kWh and another charges 79p per kWh, the difference on a 40 kWh session is £8 before any other charges are involved. That is useful, but it is not yet your full cost.
Check whether the rate applies to contactless payment, app payment or a registered account. Some networks offer a lower rate through a subscription or partner tariff. Treat the membership fee as part of the energy cost, not as an unrelated expense. If a £7.99 monthly plan saves 10p per kWh, you need to buy roughly 80 kWh that month merely to break even. Below that point, the lower advertised rate is costing you more.
Then look for session, connection, parking and overstay charges. A fee that starts once charging finishes can turn an otherwise modest top-up into an expensive stop, particularly at stations where you are delayed by a meeting, a queue or a car park exit. Parking fees deserve the same attention. They are not electricity costs, but they are a real cost of obtaining that public charge.
Speed has value, but it should not be mistaken for value for money. A 150 kW unit will usually carry a higher unit price than an AC destination charger. If you need 20 minutes to continue a journey, paying more can be entirely rational. If you are parked for three hours anyway, the slower option may deliver the same useful energy for far less. Compare chargers against the time you genuinely have, not against their maximum advertised power.
Turn the price into cost per mile
Pence per kWh is a charger price. Cost per mile is a vehicle figure. You need both, because the same public rate produces very different outcomes in different cars and conditions.
Use the efficiency your car actually achieved on that journey. If your EV used 3.2 miles per kWh and you paid 72p per kWh, your energy cost was 22.5p per mile. At 4.0 miles per kWh, the identical charging price becomes 18p per mile. Winter heating, motorway speed, wet roads, load, wind and towing can all change the result materially.
For a simple calculation, divide the total session cost by the miles driven using that energy. Alternatively, divide the rate per kWh by your miles per kWh. The first method is better when a receipt includes a fixed fee; the second is useful for quick planning.
There is one practical complication: chargers bill for energy delivered to the vehicle, while your car’s trip display may measure energy used from the battery. Charging losses mean those figures will not always match. Do not force them to match. For financial records, use the kWh and amount on the charging receipt. For driving efficiency, use the vehicle’s miles and consumption data. Over time, the gap helps you understand your real wall-to-wheel energy use rather than hiding it behind a flattering dashboard number.
A worked example
Suppose you add 36 kWh at a rapid charger priced at 75p per kWh. The electricity line is £27.00. There is also a £1.50 session fee, so the charge cost is £28.50. If those 36 billed kWh support 110 miles of driving, the public-charging cost is 25.9p per mile.
That number is more useful than saying you paid 75p per kWh. It can be compared with your home charging, previous public sessions and a petrol baseline based on the fuel price and mpg you actually use. It also makes clear whether the rapid stop was an occasional travel cost or is becoming a routine expense that needs attention.
Why the cheapest displayed rate is not always cheapest
A public charging price comparison should include availability and reliability, even though neither appears on the receipt. A charger that is out of service, blocked or constantly queued has no useful low price when you need to travel. The alternative may mean extra miles, another paid car park or a more expensive charger later in the journey.
Location changes the arithmetic too. A 55p per kWh charger ten miles out of your way is not automatically cheaper than a 69p per kWh unit on your existing route. Count the energy used for the detour, the extra time and any parking cost. There is no need to invent a complicated formula for every journey, but repeated patterns are worth recording. If the same ‘cheap’ site repeatedly adds 25 minutes to your day, its saving may be smaller than it first appears.
Charging to 100% can produce a similar trap. On many rapid chargers, the final portion of a charge is much slower. If an idle fee starts shortly after charging ends, you may also face pressure to move promptly. For a long trip, stopping twice to charge quickly may be cheaper in time and no more expensive in money than holding a bay while the battery slows down. It depends on the route, the car and the next reliable charger.
Keep a record that can be checked later
The useful record for each public session is straightforward: date, location or network, billed kWh, total paid, unit rate, any separate fee, payment method and a receipt or screenshot where available. Add the odometer reading or mileage period, and the charge becomes part of a defensible cost-per-mile record rather than a line lost in a bank statement.
This matters when you use several payment routes. Contactless transactions, charging-network wallets, roaming apps and prepaid energy blocks can obscure the price paid per individual charge. A prepaid balance is not free electricity simply because the cash left your account earlier. Record the purchase, allocate energy as it is used and keep track of the remaining balance. That gives you a blended rate where appropriate and stops costs being counted twice.
For self-employed drivers and businesses, retain VAT information exactly as shown on the receipt. Public charging is generally charged at the standard VAT rate, while domestic electricity has different treatment, so blending everything into one undifferentiated ‘charging’ total can make reporting harder. The right reclaim treatment depends on how the vehicle is used and your tax position. Your records should provide the evidence; they should not guess the tax outcome.
Amperlo is built for this unglamorous but valuable job: logging the charge while you are still at the bay, attaching the receipt and turning scattered payments into real running-cost figures. The aim is not to prove that every EV journey is cheap. It is to show what your car actually costs to run.
Use comparison to make better charging decisions
After a month or two, review public charging by use case rather than hunting for one universal winner. Separate motorway rapid charging, supermarket or destination charging, workplace sessions and emergency top-ups. Each has a different acceptable price because each solves a different problem.
You may find that public charging is a small, predictable travel expense, even at relatively high rates. Or you may see that a particular subscription, habitual rapid stop or forgotten parking fee is raising your cost per mile. Both findings are useful because they are based on your driving, not a network advert or a generic EV saving claim.
The best charger is sometimes the fastest available one, sometimes the lowest priced one and sometimes the one that lets you get home without another stop. Keep the receipt, record the miles and let the numbers tell you which is which.
