One of the big decisions for EV owners is how much to rely on home charging versus public fast charging. Both options have their place:
- Home charging is usually cheaper and more convenient
- Public fast charging is faster and more flexible, especially on road trips or for people without a driveway
But what does the real cost per kWh and cost per 100 km look like in each case? And what is a realistic mix for most drivers?
In this guide, we’ll break down the cost differences, explain the hidden factors behind each option and help you decide on the best strategy for your situation.
1. The basic price difference: kWh at home vs kWh in public
Prices vary by country, city and charging network, but there are some common patterns:
- Home electricity price often ranges from 0.10–0.30 USD / kWh
- Public DC fast charging is commonly 0.30–0.70+ USD / kWh
So a kWh at a fast charger can easily cost 2–4 times more than the same kWh at home.
To understand how this affects you, we need to translate that into cost per 100 km.
2. Cost per 100 km: home vs fast charging
Let’s assume an EV with real-world energy consumption of:
18 kWh / 100 km
We’ll compare three different electricity prices:
- Cheap home rate: 0.12 USD / kWh
- Average home rate: 0.20 USD / kWh
- Typical fast charging rate: 0.50 USD / kWh
2.1 Home charging – cheap tariff (0.12 USD / kWh)
Cost per 100 km = 18 × 0.12 = 2.16 USD / 100 km
2.2 Home charging – average tariff (0.20 USD / kWh)
Cost per 100 km = 18 × 0.20 = 3.60 USD / 100 km
2.3 Public fast charging (0.50 USD / kWh)
Cost per 100 km = 18 × 0.50 = 9.00 USD / 100 km
Even with an average home tariff:
- Home: 3.60 USD / 100 km
- Fast charging: 9.00 USD / 100 km
Fast charging is about 2.5 times more expensive per kilometre.
If your home electricity is cheap (0.12 USD / kWh), the difference is even bigger:
- 2.16 vs 9.00 USD → Fast charging is over 4 times more expensive.
3. Translating that into yearly cost
Now let’s see how the mix between home and fast charging affects your annual “fuel” bill.
Assume:
- Annual distance: 15 000 km
- EV consumption: 18 kWh / 100 km
Energy needed per year:
15 000 ÷ 100 × 18 = 150 × 18 = 2 700 kWh
We’ll compare three scenarios with an average home price (0.20 USD / kWh) and fast charging at 0.50 USD / kWh.
Scenario A – Mostly home charging (90% home, 10% fast)
- Home energy: 2 700 × 90% = 2 430 kWh
- Fast charging energy: 2 700 × 10% = 270 kWh
Cost:
- Home: 2 430 × 0.20 = 486 USD
- Fast: 270 × 0.50 = 135 USD
Total yearly cost:
621 USD / year
Scenario B – Mixed usage (60% home, 40% fast)
- Home: 2 700 × 60% = 1 620 kWh
- Fast: 2 700 × 40% = 1 080 kWh
Cost:
- Home: 1 620 × 0.20 = 324 USD
- Fast: 1 080 × 0.50 = 540 USD
Total:
864 USD / year
Compared with Scenario A, this driver spends 243 USD more per year simply because they use fast charging more often.
Scenario C – Mostly fast charging (10% home, 90% fast)
This might be someone living in an apartment with no practical home charging.
- Home: 2 700 × 10% = 270 kWh
- Fast: 2 700 × 90% = 2 430 kWh
Cost:
- Home: 270 × 0.20 = 54 USD
- Fast: 2 430 × 0.50 = 1 215 USD
Total:
1 269 USD / year
Compared with Scenario A (mostly home charging), this driver pays about:
1 269 − 621 = 648 USD more per year
The car is the same. The distance is the same. The difference is where they get their energy.
4. Cost vs convenience: what are you paying for?
Given how much more expensive fast charging is, why do people use it at all?
Because cost isn’t the only factor. Public fast charging offers:
- Speed – charge from low to high state of charge in 20–40 minutes
- Flexibility – useful on road trips and long highway journeys
- Accessibility – essential for drivers without home or workplace charging
The higher price reflects the fact that fast charging networks:
- Require expensive hardware and grid connections
- Need maintenance, support and payment infrastructure
- Often pay high demand charges to the grid operator
In other words, you are not just paying for energy—you are paying for speed, location and convenience.
For most drivers, the smart strategy is:
Use home charging as your default, and treat public fast charging as a support tool for specific situations, not as your main energy source.
5. Hidden factors in the cost comparison
Beyond the basic price per kWh, there are several subtler factors that affect real cost per kilometre.
5.1 Charging losses
Every charging session has some inefficiency:
- Energy is lost as heat in cables and inverters
- The battery management system consumes power while managing the process
Typical efficiency:
- AC home charging: often 85–95% efficient
- DC fast charging: can be similar or slightly better/worse depending on hardware and conditions
In real life, the losses are already baked into your bill for home charging and into the network’s kWh meter for public charging. You don’t need to calculate them separately unless you want to be extremely precise.
However, slower, moderate-power home charging often stays in a very efficient range, especially when the battery is not extremely cold or hot—another small win for home charging in the long run.
5.2 Idle fees and parking charges
Some fast charging networks add:
- Idle fees – extra cost per minute if you stay plugged in after charging finishes
- Parking charges – per hour or per session
This can significantly increase the real cost of a charging stop, especially if you get distracted and don’t move your car promptly after reaching a high state of charge.
Home charging rarely has such penalties (unless you pay for parking in your own building).
5.3 Battery health and high SOC charging
Fast charging is especially hard on the battery when:
- The battery is cold
- You frequently charge to very high states of charge (e.g. 90–100%)
- You use high-power DC charging as your primary charging method
While the exact impact depends on the car and battery chemistry, many manufacturers recommend:
- Using AC home charging as your main method
- Reserving high-power DC fast charging for occasional use, like trips
Over many years, heavy reliance on fast charging may:
- Increase battery degradation
- Reduce your real-world range
- Potentially affect resale value
These “indirect costs” don’t show up in your charging bill, but they can influence the total cost of ownership.
6. Use cases: when each option makes sense
6.1 When home charging is clearly best
Home charging is almost always the best option when:
- You have a driveway, garage or assigned parking with power
- Your electricity price is reasonable and stable
- You drive a moderate or high annual mileage
- Your daily distance is well below what a full charge can deliver
In this case, your daily charging may look like:
- Plug in at home in the evening
- Charge overnight on a timer, often at off-peak rates
- Wake up every morning with a comfortable state of charge
Your cost per kilometre will be close to the home charging numbers we calculated earlier, and you’ll rarely need to think about energy mid-journey.
6.2 When fast charging is necessary
Public fast charging becomes necessary or very useful when:
- You live in an apartment without home charging
- Your job involves many long highway drives
- You take frequent long road trips beyond your car’s range
- You temporarily need extra fast charging during a move, renovation or tariff limitation
In these situations, your cost per kilometre will be higher than pure home charging, but the EV can still make sense:
- If your area’s public charging prices are reasonable
- If you still get some share of cheaper energy (workplace AC charging, etc.)
- If the non-financial benefits of EVs matter to you (quiet, performance, environment)
6.3 Hybrid strategy: the most common real-world pattern
For many EV owners, the real-world pattern is a hybrid of both:
- 90–95% of energy from slow, cheap home or workplace charging
- 5–10% from public fast chargers on long trips or occasional busy days
This strategy:
- Keeps average cost per kWh close to home charging
- Gives you all the convenience and freedom of fast charging when you actually need it
- Minimizes the impact of high DC charging prices on your yearly budget
Even if you increase your fast charging share to 20–30%, your average cost is still dominated by the cheaper home energy.
7. Example: mixed home + fast charging cost per 100 km
Let’s build one more concrete example.
Assumptions
- EV consumption: 18 kWh / 100 km
- Home price: 0.18 USD / kWh
- Fast charging price: 0.55 USD / kWh
- Charging mix: 80% home, 20% fast
7.1 Effective price per kWh
Effective price = (0.8 × 0.18) + (0.2 × 0.55)
= 0.144 + 0.11
= 0.254 USD / kWh
7.2 Cost per 100 km (mixed)
Cost per 100 km = 18 × 0.254 ≈ 4.57 USD / 100 km
If you used only home charging, you’d pay:
18 × 0.18 = 3.24 USD / 100 km
So with 20% fast charging, you’re paying:
- Around 1.33 USD more per 100 km than a pure home charger, but
- Still far less than a gasoline car in many countries
This shows that you don’t have to be “perfect” to keep EV running costs low. Even with some fast charging in the mix, the numbers remain attractive.
8. Home vs fast charging from a time perspective
It’s not just about money. Time also matters.
8.1 Time spent plugged in vs time spent waiting
Home charging:
- You plug in for several hours (often overnight)
- But you don’t sit there watching it—you sleep, work or live your life
- Real “waiting time” is close to zero
Fast charging:
- Charging stops are faster (20–40 minutes), but
- You must stay near the charger, move the car when done and resume your trip
- On a long journey, multiple stops add up
From a purely time-efficiency perspective:
- Home charging is best for day-to-day energy needs
- Fast charging is best for extending range mid-trip, where it replaces time you might spend at a gas station or rest stop anyway
The ideal approach is again a combination: fill most of your energy “slowly in the background” at home, and use fast charging only for the extra distance that home energy cannot cover.
9. How to choose the right balance for your situation
Here’s a simple process to decide how much you should rely on home charging vs public fast charging.
Step 1: Map your typical weekly driving
Ask yourself:
- How many km/miles do I drive on a normal weekday?
- How many km on a typical weekend?
- How often do I do long trips beyond my EV’s one-charge range?
If most days are well within your car’s range, home charging can handle almost everything.
Step 2: Check your home charging capability
Consider:
- Do you have a dedicated parking spot with access to power?
- What is your maximum charging power at home (e.g. 3.7 kW, 7.4 kW, 11 kW)?
- Is your household wiring and tariff suitable for regular EV charging?
If the answer is “yes” to these, home charging should be your main energy source.
Step 3: Estimate your fast charging needs
Estimate:
- How many long trips per year?
- How many kWh will you likely add via fast chargers?
Even a few big journeys may represent only 5–15% of your annual energy use.
Step 4: Calculate your expected average cost
Use:
- Home price per kWh
- Fast charging price per kWh
- Estimated percentage from each
Then:
Effective price per kWh = (Home share × home price) + (Fast share × fast price)
Cost per 100 km = EV consumption × effective price
This will give you a realistic mixed cost per 100 km and per year.
10. Key takeaways
- Home charging is usually the cheapest and most convenient way to power an EV, with typical costs of 2–5 USD per 100 km depending on electricity prices and consumption.
- Public fast charging is often 2–4 times more expensive per kWh than home electricity, pushing cost per 100 km closer to 7–15 USD in many markets.
- Fast charging offers speed and flexibility, not low cost—it’s perfect for long trips and occasional top-ups, but expensive as a primary energy source.
- The most common and efficient pattern is a hybrid strategy:
- Use home charging for 80–95% of your energy
- Use fast charging to extend range on trips or when home charging isn’t available
- Even with 20–30% fast charging in the mix, EVs often remain cheaper to run than gasoline cars, especially when you have reasonable home electricity rates.
If you understand the cost breakdown and plan your charging habits around it, you can enjoy both the convenience of fast charging and the low running costs of home charging—without any surprises on your energy bill.