Transport

EV Charging Cost Calculator

Estimate the electricity and cost to charge an electric car from its battery size, charge window, efficiency losses, and electricity price — at home or on a public charger with session fees. An energy-cost estimate, never a range promise.

Last updated: September 30, 2026

Your result · Total charging cost

$6.00

Grid energy drawn: 40kWh
Energy cost: $6.00

Energy added to battery: 36kWh
Session feesFlat fees across all sessions.: $0.00

Free · No signup · Math stays in your browser

What your result means

Total charging cost is the headline: grid energy at your price plus any public markups and flat session fees, across all sessions. Grid energy shows what the meter (or charger) actually measures.

Energy added to battery is smaller than grid energy — the gap is charging loss. A 10% loss on every charge adds up across a year of driving.

How the calculation works

Multiply battery capacity by the charge window to get energy stored in the battery.
Divide by efficiency to get grid energy — at 90%, 36 kWh stored draws 40 kWh from the wall.
Multiply grid energy by price plus any public adder, then add flat session fees across all sessions.

Formula

stored = capacity × (target − current) ÷ 100; grid = stored ÷ efficiency; cost = grid × price (+ fees)

Energy storedbattery kWh × (target % − current %) ÷ 100
Grid energystored ÷ (efficiency ÷ 100)
Energy costgrid × (price + public adder)
Totalenergy cost × sessions + session fee × sessions

Worked examples

Example: 60 kWh pack, 20→80%, 90% efficiency at 0.15/kWh
batteryKwh: 60currentSoc: 20targetSoc: 80rate: 0.15efficiency: 90sessions: 1
Result: Energy added to battery 36 · Grid energy drawn 40 · Energy cost $6.00 · Session fees $0.00 · Total charging cost $6.00
Example: public charging with 0.10 adder + 2.00 session fee
batteryKwh: 60currentSoc: 20targetSoc: 80rate: 0.15efficiency: 90sessions: 1publicFee: 0.1sessionFee: 2
Result: Energy added to battery 36 · Grid energy drawn 40 · Energy cost $10.00 · Session fees $2.00 · Total charging cost $12.00

Assumptions

What this calculation takes for granted — check these before relying on the result.

Assumptions:

Default values are an example starting point — use your car’s usable capacity.
Efficiency is treated as constant across the session; it actually varies with charge level.
Battery capacity entered is usable capacity, not the nominal pack rating.
Sessions repeat identically; driving between charges is not modelled.

Limitations

Why your real figure may differ:

Nominal pack size exceeds usable capacity — buffers at top and bottom mean 60 kWh rated is not 60 kWh usable.
Cold weather, battery preconditioning, cabin heating, and DC fast-charge taper all raise real consumption.
Public pricing varies wildly: per-kWh, per-minute, idle fees, and subscriptions change the math per network.
This estimates charging cost only — never driving range, which depends on speed, weather, and terrain.

Frequently asked questions

What are charging losses?

Energy lost as heat in the charger, cables, battery management, and cooling. Level 2 home charging typically loses 5–15%; DC fast charging and cold weather lose more.

Nominal vs usable battery capacity?

Manufacturers quote the full pack; software locks buffers at the top and bottom to protect the battery. Always enter usable capacity — often 5–10% less than nominal.

Why does public charging cost more?

Networks add per-kWh markups, per-minute billing, session or idle fees, and sometimes subscriptions. Home charging at your residential rate is usually the cheapest option.

Does cold weather change charging cost?

Yes — battery heating and preconditioning draw extra energy, efficiency drops, and DC charging slows (which matters on per-minute billing). Winter sessions cost measurably more.

How many kWh do I need for a full charge?

Roughly (target − current)% of usable capacity, divided by efficiency. A 60 kWh car from 20→80% at 90% needs about 40 kWh from the grid.

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