EV Charging Cost Calculator — Cost Per Mile, Per Charge & Per Year

What this computes

"EVs are cheap to run" is true with home charging and optimistic without it. This calculator gives the honest number: it includes charging losses, blends your home/public split, and converts everything into cost per mile, per full charge, and per year — the figures you actually budget with.

The math

wall kWh/mi  = (1 / efficiency) / (1 − loss)
blended rate = home·(1 − publicShare) + public·publicShare
cost/mile    = wall kWh/mi × blended rate
annual cost  = annual miles × cost/mile

The (1 − loss) term is the part casual estimates skip; it's why the wall draws more energy than the battery stores and why a "full charge" costs more than battery size times the rate.

The EV's running-cost advantage lives almost entirely in the home electricity rate. Public-only charging can erase it.

How to use this

Use real-world efficiency, not the EPA rating — speed, cold, and climate control all reduce mi/kWh.
Be honest about the public share. No home charger means a high public share and a very different cost.
Keep loss around 10% for home Level 2; raise it for cold climates or heavy fast-charging.
Run the gas comparison against the specific car you'd otherwise buy, not a worst-case guzzler.

Why charging losses matter

Charging is not 100% efficient. The gap between wall energy and battery energy is real money over a year:

Conversion. AC from the grid is converted for the battery; the onboard charger isn't lossless.
Thermal management. Battery heating/cooling during charging draws extra energy, more so in extreme temperatures.
Trickle and overhead. Slow Level 1 charging is proportionally less efficient than Level 2.

What this calculator doesn't model

Time-of-use tariffs. Off-peak overnight rates can cut home cost substantially — use your effective off-peak rate.
Charging subscriptions / idle fees. Network membership and connection fees aren't separated out.
Battery degradation. Efficiency drifts slightly over the pack's life; not modeled here.
The rest of ownership. Energy is one line — see True Cost of Ownership and Gas vs Electric.

Frequently asked questions

How is EV charging cost calculated? +

Energy per mile is one divided by your miles-per-kWh efficiency. That battery-side figure is grossed up by charging losses to get the energy actually billed at the wall, then multiplied by your electricity rate. Cost per year is simply that per-mile cost times annual mileage. Home and public rates are blended by how much charging you do at each.

What are charging losses and how big are they? +

Not all energy drawn from the wall reaches the battery — some is lost to AC/DC conversion and thermal management. Home Level 2 charging typically loses about 8-12%; it can be higher in cold weather or on slow Level 1, and DC fast charging has its own losses. Estimates that multiply battery size by the rate and ignore this understate real cost by roughly 10%.

Is home or public charging cheaper? +

Home is almost always far cheaper — residential electricity is commonly $0.12-0.22/kWh, while public DC fast charging often runs $0.40-0.60/kWh. The blended-rate input captures this: an EV that's cheap to run on home charging can cost as much as a gas car if you rely heavily on public fast charging.

Why doesn't a full charge equal battery size times the rate? +

Because of losses, charging a 75 kWh battery pulls more than 75 kWh from the wall. This calculator divides battery size by (1 − loss) before applying the rate, which is why the full-charge figure is higher than the naive estimate.

How does this compare to a gas car? +

Enter a comparison MPG and gas price to see the annual difference. The EV advantage is largest with cheap home electricity and an inefficient gas comparison; it shrinks with heavy public charging or against an efficient hybrid. The calculator shows the honest, losses-included number rather than the optimistic one.

Is this an exact figure? +

It's a solid planning estimate. Real efficiency varies with speed, climate, and terrain; charging losses vary by charger and temperature. AutoMath is an educational tool — use conservative (lower) efficiency and (higher) loss figures for budgeting.

Related calculators

Fuel Cost — the gas equivalent of this math.
Gas vs Electric Total Cost — lifetime cost, not just energy.
True Cost of Ownership — energy plus depreciation and the rest.

Including the losses nobody counts: what it really costs to charge an EV.

AutoMath is an educational tool. The numbers above depend entirely on assumptions you provide and are not financial advice.