How to Calculate EV Charging Cost (Simple UK Guide for Drivers & Businesses)

You’ve plugged in the car. The lights start blinking. But what is this actually costing you?

If you’re not totally sure, you’re in good company. Most drivers of a typical electric car know it’s usually cheaper than petrol, but couldn’t explain how to calculate EV charging cost if you asked them on the spot.

The reality? You only need a couple of numbers to work out the true cost to charge your vehicle:

• How much a home charge really costs
• Whether rapid chargers are worth the extra
• What you’re paying per mile and per month
• And, if you run a hotel, car park or attraction, what it costs to offer charging to your guests

ZOLB EV works with businesses and destinations across the UK every day, so turning those numbers into clear answers is what we do. In this guide, we’ll break it down in simple steps, so you can finally see what each kWh is really doing to your wallet.

Let’s dive in.

The basic formula for EV charging cost

At its core, calculating EV charging cost comes down to a simple formula:

Charging cost = Energy added (kWh) × Electricity price (per kWh)

Two terms really matter:

1. Battery size (kWh) – how big your “fuel tank” is.
2. Electricity unit rate (price per kWh) – what you pay for each unit of electricity.

If you fill a 60 kWh battery from empty at a home rate of roughly 26p per kWh, the cost is:

60 kWh × £0.26 ≈ £15–£16 for a full charge.

That’s the big picture. Now let’s walk through it step by step for real-world situations.

How to calculate EV charging cost at home

1. Find your battery size

Your car’s battery size is usually shown:

• In the owner’s manual
• On the manufacturer’s website
• In spec sheets or EV review sites, when you search “[your model] battery size”

Common sizes range from around 40 kWh on smaller cars up to 80–100 kWh on larger SUVs.

2. Look up your electricity unit rate

Next, take a recent electricity bill and find the unit rate for electricity, expressed as pence per kWh.

Under the current Ofgem price cap (late 2025), the average electricity unit rate is just over 26p per kWh, with a daily standing charge of roughly 54p per day.

For the purposes of per-charge maths, focus on that unit rate. The standing charge affects your total electric bill, but not the cost of one specific charging session.

If you’re on an EV or off-peak tariff, check whether your night-time rate is lower. Some off-peak tariffs offer overnight rates around 10–15p per kWh, sometimes even less.

3. Work out how much charge you’re adding

You rarely charge from 0–100%. A more typical pattern for electric cars is topping up, say, from 20% to 80%.

To account for that, use this version of the formula:

Cost = Vehicle battery size × % added × Price per kWh

Where % added is written as a decimal (so 60% becomes 0.6).

Example: 20–80% top-up at home

Imagine you have a 64 kWh battery. You arrive home at 20% and charge to 80%.

• Percentage added: 60% to 0.6
• Battery size: 64 kWh
• Home rate: 26p/kWh to £0.26

Cost of that charging session
= 64 × 0.6 × 0.26
= 64 × 0.156
≈ £10

So, that everyday top-up is roughly £10 on a typical home electricity tariff.

Standing charges and smart tariffs, do they matter?

Standing charges

In the UK, most tariffs include a daily standing charge (around 54p a day for electricity on the current cap).

That fee applies whether you charge an electric car or not. It does influence your total annual energy spend, but when you’re just asking “What did this charging session cost?”, you can safely ignore it and only use the unit rate per kWh.

Off-peak and EV tariffs

EV-friendly tariffs often have a cheap overnight window, for example, from midnight to 5 am at around 10–15p per kWh.

Using our 64 kWh, 60% top-up example on a 10p/kWh off-peak rate:

64 × 0.6 × 0.10 = 64 × 0.06 = £3.84

Simply moving your charging into a cheap overnight window can cut the same top-up from roughly £10 down to under £4.

How to calculate public EV charger cost

Public charging prices vary more because they’re influenced by a few different factors, but the formula stays exactly the same:

Cost = Energy used (kWh) × Price per kWh

Typical public charging prices in the UK are:

• Slow/fast AC (3–49 kW): around 50–57p per kWh
• Rapid/ultra-rapid DC (50 kW+): around 75–80p per kWh

Again, you’re mainly paying extra for speed and convenience.

Example: rapid top-up on a long journey

Take the same 64 kWh car, charged from 20% to 80% on a rapid charger at 76p/kWh:

• Battery: 64 kWh
• Percentage added: 60% to 0.6
• Price: £0.76 per kWh

Cost = 64 × 0.6 × 0.76
= 64 × 0.456
≈ £29

Compare that with the same top-up:

• Home standard tariff (~26p/kWh): about £10
• Home cheap overnight (~10p/kWh): roughly £4
• Rapid public (~76p/kWh): close to £29

Public rapid charging is brilliant for motorway journeys in an electric vehicle, but expensive if you depend on it all the time.

How to calculate EV charging cost per mile

For many people, the most useful figure is cost per mile, because it lets you compare directly with petrol or diesel.

The key is your car’s efficiency, measured in miles per kWh. Many modern EVs average 3–4 miles per kWh, depending on driving style, weather and road type.

The formula is:

Cost per mile = Electricity price per kWh ÷ Miles per kWh

Let’s assume your car averages 3.5 miles per kWh.

Home off-peak (10p/kWh)

• 10p ÷ 3.5 ≈ 2.9p per mile

Typical home rate (26p/kWh)

• 26p ÷ 3.5 ≈ 7–8p per mile

Public slow/fast (~52p/kWh)

• 52p ÷ 3.5 ≈ 15p per mile

Rapid / ultra-rapid (~76p/kWh)

• 76p ÷ 3.5 ≈ 22p per mile

Even with higher energy prices than a few years ago, home charging, especially off-peak, stays far cheaper per mile than rapid public chargers.

Estimating your monthly EV charging cost

Once you’ve got your cost per mile, working out a rough monthly figure is simple:

Monthly cost ≈ Miles driven per month × Cost per mile

Suppose you drive 800 miles a month and mostly charge at home at around 7.5p per mile (a 26p/kWh tariff with 3.5 miles per kWh efficiency):

800 × £0.075 = £60 per month

If you can push most of that charging into a cheap off-peak window at roughly 3p per mile, the same mileage costs around £24 per month.

Real figures will go up or down depending on your car, your tariff and your driving style, but the calculation stays the same.

For businesses: how to calculate the cost of offering EV charging

If you’re a hotel, resort, spa, attraction, retail park, workplace or other destination, your angle is a bit different. You want to know:

• What does each kWh cost you?
• What should you charge electric car drivers?
• What margin and extra revenue can you expect?

ZOLB EV specialises in commercial charging solutions across the UK, providing hardware, installation and software for businesses that want to attract EV drivers and generate new revenue.

1. Work out your true cost per kWh

Commercial electricity contracts vary, but average non-domestic prices (including taxes and levies) are often in the low-to-mid 20s p/kWh.

On top of that, add:

• Network or roaming fees
• Back-office software and payment processing
• Maintenance and support

If, for example:

• Your electricity costs you 24p/kWh
• Your software and transaction costs add another 5p/kWh

Then your total cost per kWh is about 29p.

2. Set a fair customer tariff and margin

Public prices for slow/fast AC chargers typically sit around 50–57p/kWh, with rapid chargers nearer 75–80p/kWh.

If your total cost is 29p/kWh, you might set a customer tariff like:

• 49p/kWh for destination AC charging at a hotel or attraction

That gives you a gross margin of 20p/kWh, while still being competitive and convenient for your guests.

If a visitor uses 40 kWh during an overnight stay:

• Customer pays: 40 × £0.49 = £19.60
• Your cost: 40 × £0.29 = £11.60
• Gross profit: £8.00

Many businesses offering EV charging see meaningful monthly revenue, especially when you include the indirect value of longer visits, increased dwell time, and better customer satisfaction.

Quick recap: your EV charging cost toolkit

To wrap up, here’s a short checklist you can come back to whenever you want to calculate EV charging cost:

At home:

• Find your battery size and electricity unit rate.
• Estimate the percentage you’re charging.
• Use Cost = Battery size × % added × Price per kWh.
• Repeat using off-peak rates if you have them.

Public charging:

• Look at the price per kWh on the charger or app.
• Multiply by the energy added.
• Expect rapid charging to cost significantly more.

Per mile & per month:

• Note your miles per kWh from your EV’s display.
• Use Cost per mile = Price per kWh ÷ Miles per kWh.
• Multiply miles per month for a rough monthly cost.

For businesses:

• Add energy + software + network costs for your true cost per kWh.
• Set a tariff that covers costs and delivers a fair margin.

Turn EV charging into an asset, not a headache

Right now, EV charging can feel like a box to tick. But for the right sites, it’s a reason for guests to choose you over the place down the road, and a new, reliable revenue stream on top.

Whether you’re a driver trying to get a grip on running costs or a business owner deciding how to offer charging, knowing how to calculate EV charging cost is the first step. The next step is putting that knowledge to work.

If you’re a hotel, spa, attraction, retail park or workplace and you want charging that’s easy to use, fairly priced and built to generate meaningful revenue, ZOLB EV can help you:

• Understand the best charger mix for your site
• Design and install a setup that fits your brand and your budget
• Keep everything running smoothly with ongoing maintenance and support
• Take payments seamlessly and set smart, flexible tariffs
• Model your revenue and ROI so you know what each charger can deliver

You bring the destination; ZOLB EV brings the charging.

Turn your car park into a reason guests stay longer, spend more and come back again, starting with one conversation.

For UK businesses planning charge points, see commercial EV charger installation, OZEV and grants and our installation guide.