Most EV cost chat focuses on pence per kWh, but what you actually feel day to day is pence per mile.
In April 2026, Ofgem’s latest energy price cap update gives us a useful baseline: if you are on a standard variable (default) tariff and pay by Direct Debit, electricity is 24.67p per kWh on average (plus a daily standing charge).
That number does not mean everyone pays exactly that. Plenty of EV drivers use smart tariffs with much cheaper overnight rates, and public charging can be much more expensive. But it is a solid reference point for the “what does normal home electricity cost right now?” question.
The key conversion: kWh to miles
To convert a home electricity rate into a cost per mile, you need one more number: your EV’s efficiency.
- Cost per mile = (pence per kWh) ÷ (miles per kWh)
Typical real-world EV efficiency varies a lot, but as a quick rule of thumb:
- Good conditions: 4.0 miles/kWh
- Mixed driving: 3.5 miles/kWh
- Motorway + cold weather: 3.0 miles/kWh (or lower)
Example: April to June 2026 price cap electricity into pence per mile
Using Ofgem’s average electricity unit rate of 24.67p/kWh:
- At 4.0 miles/kWh: about 6.2p per mile (24.67 ÷ 4.0)
- At 3.5 miles/kWh: about 7.0p per mile (24.67 ÷ 3.5)
- At 3.0 miles/kWh: about 8.2p per mile (24.67 ÷ 3.0)
That 3.5 miles/kWh example landing at roughly 7p per mile is a nice sanity check. It is also why a lot of “home charging” reimbursement policies end up looking like single-digit pence per mile.
Why smart EV tariffs can change the maths
If you charge mostly overnight on a smart EV tariff, your marginal unit rate can be dramatically lower than the price cap baseline.
For example, Octopus Energy’s Intelligent Octopus Go marketing currently references 8p/kWh for smart charging.
At 3.5 miles/kWh, that works out at:
- About 2.3p per mile (8 ÷ 3.5)
Even if your real blended rate is higher (because you do some top-ups outside the cheap window), it shows why it is worth knowing which rate you are actually paying for EV charging, not just what your “headline tariff” is.
What about the standing charge?
Ofgem’s price cap also includes a daily standing charge (an average of 57.21p/day for electricity on default tariffs during the same period).
Should you include that in your EV pence-per-mile?
- If you are trying to estimate the marginal cost of charging the car, most people ignore standing charge, because you pay it whether you charge the EV or not.
- If you are trying to understand your true household electricity cost, you might want to allocate some standing charge across total kWh usage, then treat that as a slightly higher effective p/kWh.
There is no single “correct” answer. The important thing is to be consistent, especially if you are comparing month to month.
Public charging: treat it as a separate bucket
Public charging prices vary wildly by network, location and charger speed. For practical tracking, it is often easiest to treat public charging as a separate cost bucket from home charging, rather than trying to blend everything into one number.
That is especially true if you drive for work. A month of mostly home charging plus one long motorway trip with rapid chargers can make your average “pence per mile” jump noticeably.
What to record (so you can calculate it later without guesswork)
You do not need perfect data to get useful numbers, but you do need repeatable data. A simple approach is:
- Mileage (business vs personal)
- Charging type (home, public, mixed)
- Notes when something is unusual (hotel charging, rapid charging on a long trip, reimbursed charging card, and so on)
Once you have that, you can apply the right electricity rate for the right period (and update it when Ofgem reviews the cap again).
How Mileage Tracker helps
Mileage Tracker is built for the boring part, the part that saves you hours later:
- Log journeys as you go (and keep business vs personal miles separate).
- Export totals when you need to claim mileage or understand running costs.
- Add lightweight notes so you can spot “that was the rapid-charging week” instantly when you look back.
Practical takeaway: pick one baseline (for example, Ofgem’s price cap unit rate for the quarter), then track your mileage cleanly. If you later switch to a smart EV tariff or your driving efficiency changes seasonally, you will be able to see the impact immediately.
Sources
- Ofgem: Changes to energy price cap between 1 April and 30 June 2026 (unit rates and standing charges)
- Octopus Energy: Intelligent Octopus Go (example of an EV smart charging rate)
Track every mile with less faff
Ready to keep your EV mileage, trips, and running costs tidy?
Mileage Tracker helps you log journeys, stay on top of costs, and keep cleaner records for work or personal driving.