The Real Cost of Charging an EV at Home vs. a Fast Charger (and How to Track It)
One of the more surprising things new EV owners learn isn't that charging is cheap — it's that charging can be cheap, but how cheap depends enormously on where you do it. The gap between charging overnight at home and topping up at a public fast charger on a road trip is often the difference between an EV that costs a fraction of a gas car to run, and one that's only modestly cheaper. Most people never actually calculate this gap for their own car. Here's how, and why it's worth tracking properly rather than estimating.
Why the cost per kWh varies so much
Home charging (Level 1 or Level 2) is usually billed at your regular residential electricity rate, sometimes with a cheaper overnight or off-peak rate if your utility offers time-of-use pricing. This is the cheapest way to charge for the vast majority of EV owners, often by a wide margin.
Public fast charging (DC fast charging) is priced differently — often per kWh at a noticeably higher rate than residential electricity, sometimes per minute instead, and frequently with an added cost for non-members of that network's subscription program. The convenience of adding 200+ km of range in 20 minutes comes at a real premium, which makes sense: the network is paying for high-power infrastructure and often a demand charge from the utility that residential customers don't face.
Level 2 public charging (the kind you find at shopping centres, workplaces, or hotels) usually sits somewhere in between — slower than fast charging, but often priced closer to (or sometimes even cheaper than) home rates, especially when it's free or included as an amenity.
Working out your own numbers
You don't need to guess at this — you can calculate it directly from your own charging sessions, which is far more useful than a generic "EVs cost X to run" estimate that doesn't reflect your actual rates, your actual vehicle's efficiency, or your actual mix of home vs. road charging.
- Step 1: Find your cost per kWh for each charging source. For home charging, check your electricity bill for your rate per kWh (note if you're on time-of-use pricing, since charging at 11pm vs. 6pm can mean a meaningfully different rate). For public charging, the rate is usually shown on the charger or in the network's app before you start.
- Step 2: Track kWh added and total cost for every session, not just occasionally. A single data point doesn't tell you much — efficiency and pricing both vary by season, by driving style, and by network. You want enough sessions logged to see a real pattern, separated by charging source.
- Step 3: Calculate cost per 100 km (or per mile) for each source separately, not blended together. If you charge 80% at home and 20% on road trips, blending the numbers hides how much of your spend the road-trip charging is actually responsible for — even though it's a small share of your charging events, it can be a disproportionate share of your cost.
- Step 4: Compare against your previous gas vehicle, if you have the numbers, using actual cost per 100 km rather than a rough fuel-economy memory. This is usually the number people are most curious about and least likely to have calculated properly, because it requires both fuel and energy history in comparable units.
What this actually looks like in practice
As a rough illustration (your actual numbers will depend on your local electricity and gas prices, and your vehicle's specific efficiency): home charging on an off-peak residential rate often lands well below the cost of running an equivalent gas car per 100 km. Public fast charging, especially at premium per-minute network pricing, can sometimes close most of that gap — particularly for road trips where you're fast-charging more often and for shorter, less efficient bursts. The household that only ever charges at home and the household that does a lot of long-distance fast charging can end up with quite different real-world savings, even with the same car.
If you're used to thinking in miles rather than kilometres, the same pattern holds: a US driver charging mostly at home on a typical residential rate will often see a cost per mile a fraction of what an equivalent gas car costs to run, while someone who leans heavily on DC fast charging for road trips — paying a per-minute or premium per-kWh rate at the plug — will see that per-mile cost climb, sometimes close to gas-car territory on the fast-charging portion alone. The math is the same whether you're logging kWh per 100 km or cost per mile; what matters is tracking the two charging sources separately rather than blending them into one average.
This is exactly why a single average "EVs save you $X a year" headline number is close to meaningless for any individual driver — the home/fast-charging mix matters more than the headline efficiency rating of the car itself.
Why this is hard to track with most tools
Most fuel-tracking apps weren't built with charging sessions in mind at all, so there's nowhere to log kWh, charger type, or location properly. Most EV-specific charging trackers handle this part well, but few distinguish cleanly between charging sources in their reporting — you might see total kWh and total cost, but not a clean breakdown of "home" vs. "fast charger" cost per 100 km side by side, which is the number that actually answers the question people are asking.
Carspel logs each charging session with location, cost, and kWh added, calculates kWh/100 km automatically, and includes a full breakdown in the Energy & cost summary report — so the home-vs-fast-charging split (and the comparison against a gas vehicle in the same household, if you have one) is something you can actually see, not something you have to reconstruct from memory and a stack of receipts at tax time.
The takeaway
Charging an EV is, for most people, genuinely cheaper than buying gas — but exactly how much cheaper depends on a mix of decisions (mostly: how often you charge at home vs. on the road) that's easy to lose track of without logging it properly. If you want a real answer instead of a marketing number, the only way to get one is to log every session, separate by source, and look at cost per 100 km rather than total spend. Once it's broken down that way, it usually becomes obvious — favourably or not — exactly how good a deal your charging habits actually are.