EV Charging Cost

Features

• Home, public level 2 and DC fast side by side, the same energy priced three ways
• ⚠️ Charging losses on their own line: 42 kWh into the battery, 47.7 kWh out of the meter; AC and DC losses are separate, because DC bypasses the on-board charger
• ⚠️ Public service fees counted per kWh, listed apart from electricity and added to the total
• Peak vs off-peak compared: overnight charging is priced as the money it saves
• Cost per km and per 100 km (based on the range actually added, not the full-charge range)
• Enter a yearly distance and you also get the cost of a year, and how much more a year of fast charging costs
• Vehicle presets (city car / compact / mid-size sedan / large SUV) fill in battery size and range in one click
• Every field is a dropdown of typical values, with a custom option when yours is not listed
• ⚠️ A target below the current charge gives 0, never a negative
• Computed locally, with no network requests

How to use

1. Pick a vehicle preset, or leave it on custom and type the battery size and range yourself
2. Choose the current charge and the level to charge to
3. Enter your peak and off-peak home rates (pick “no time-of-use rate” if you do not have one)
4. Enter the public rates and service fees from the charger; leave the losses at their defaults if unsure
5. The three columns show the cost of each method, and a yearly figure appears once you enter a yearly distance

FAQ

Why does 42 kWh into the battery draw 47 from the meter?

Because charging has losses. AC charging runs through the on-board charger, which converts AC to DC at less than perfect efficiency, and current entering and leaving the battery heats its internal resistance. Together that is typically 10–15%, so 42 kWh into the battery draws roughly 47–49 kWh from the grid. DC fast charging bypasses the on-board charger and loses less — which is why this tool asks for the AC and DC losses separately. Those losses are real money and must not be omitted from a cost calculation, so they get their own line here.

How much cheaper is home charging than public charging?

Same car, same charge window — the whole difference is price and fees. Home charging is on a domestic tariff (and can use an off-peak rate) with no service fee. Public level 2 is usually a commercial tariff plus a service fee, commonly around twice the home cost. DC fast charging is dearer still, often three to five times home. That is what the three columns are for: change a few numbers and you can see the real gap where you live. Note that what you buy with fast charging is time, not energy — a daily commute rarely needs it.

How much does an EV save compared with a petrol car?

Two steps. Take the yearly figure from this tool as the EV’s annual energy cost, then use fuel consumption calculator with the same yearly distance and your litres per 100 km to get the petrol car’s annual fuel cost. The difference is what you save at that mileage. The gap comes almost entirely from cost per km: an EV on an off-peak home rate is often a few cents per km, while a petrol car is usually several times that — over 15,000 km a year the difference is substantial.

What if my tariff has no peak and off-peak rates?

Set the off-peak rate to “no time-of-use rate”. The tool then prices everything at the peak rate, drops the “saved overnight” row and omits the off-peak scenario entirely — rather than computing with a rate you do not have. If you do have one, enter it and the tool tells you straight away how much overnight charging saves you.

I picked a vehicle preset and changing the battery size does nothing?

When a preset is active the battery size and range come from the preset, and those two dropdowns are greyed out — otherwise the screen would contain an input that appears to do nothing. Pick custom to type your own values and both dropdowns become editable again. The presets only go as far as vehicle class (city car / compact / mid-size sedan / large SUV): with three languages and a currency-neutral English page, a per-model database would go stale and could never cover every market.