How EV Charging Cost Is Calculated in United States
How does this calculator estimate the cost and time to charge an electric vehicle (battery electric vehicle / BEV)? This page opens up the machine: the exact formula, the variables it uses, and where every electricity tariff comes from, including the date each was verified. The goal is transparency, so you can check for yourself every figure shown for United States.
By mht-dev, Frontend Engineer & Creator
A frontend engineer who bought a first electric car in March 2026 and built EV Charge Calculator while working out the real cost of charging it, writing every guide from an everyday new EV owner's perspective.
What does the calculator work out?
The core calculation is simple and country-agnostic: the calculator converts a battery-percentage difference into energy (kWh), then uses that energy to work out the cost and the time. There are no magic numbers, just three basic formulas run over the specific car data and the electricity tariff you pick. Because the logic is pure, the same inputs always produce the same result, and we can test it in isolation from the display.
The input variables are: the car's battery capacity (kWh), the current and target battery percentages (%), the charger power (kW), and the electricity rate per kWh. For an electric vehicle (BEV) already in the preset list, the battery capacity and peak DC charger power are filled in automatically; you only adjust the percentages and the rate. All of those values feed the formula below.
The formula we use
- Energy needed
- energy (kWh) = battery capacity × (target % − current %) ÷ 100
- Charging time
- time (hours) = energy ÷ charger power (kW)
- Cost
- cost = energy × electricity rate per kWh
Where do the tariff figures come from?
This calculator does not guess the electricity price. Every tariff comes from an official publication: the regulated electricity tariff for the residential rate, and the published public DC fast-charging tariff. Each value is stored together with the date it was verified. The table below shows the tariffs currently active for United States, with their source and date, so every cost estimate can be traced back to its origin.
Because this app is fully static and does not fetch tariff data live when you open it, rates are updated by rebuilding and re-publishing the site whenever an official value changes, usually at the quarterly tariff review. The latest update date is shown below the table so you know how current the figures are. Public DC fast charging sometimes adds a per-session service fee that this per-kWh calculator does not model.
Electricity tariff sources
| Tariff | Rate per kWh | Source | As of |
|---|---|---|---|
| US average residential | $0.18 | EIA Electric Power Monthly — US residential average | 2026-05-27 |
| California residential | $0.30 | EIA / Choose Energy — California residential | 2026-05-27 |
| Texas residential | $0.16 | EIA — Texas residential (deregulated) | 2026-05-27 |
| Public Level 2 (AC) | $0.30 | MyVoltCost / Recurrent 2026 network comparison | 2026-05-27 |
| Public DC fast charging | $0.48 | Electrify America / EVgo published rates (mid-market) | 2026-05-27 |
Rates updated 2026-05-27
A worked example: home vs public DC charging
To show the formula and tariffs above at work, the following table uses a popular electric vehicle in United States and charges from 20% to 80%, the most realistic everyday range. Compare the cost and time at home (residential tariff, AC charger) versus at a public DC fast charger (public DC tariff, fast charging). Every figure is computed with exactly the same formula explained above; nothing is written by hand.
| Scenario | Energy | Time | Cost |
|---|---|---|---|
| At home (AC) 20% → 80% | 46.8 kWh | 4 hours 15 minutes | $8.42 |
| Public DC 20% → 80% | 46.8 kWh | 11 minutes | $22.46 |
Frequently asked questions
How does the calculator work out EV charging cost?
- The calculator converts a battery-percentage difference into energy (kWh) using the car's battery capacity, then multiplies that by the electricity rate per kWh for the cost and divides it by the charger power for the time. For example, charging from 20% to 80% at home costs about $8.42, while at a public DC fast charger it is about $22.46.
Are the electricity tariffs used accurate and up to date?
- Yes. Each tariff is taken from an official, dated publication and stored with the date it was verified, shown in the sources table on this page. Tariffs are updated by rebuilding the site when an official value changes, typically at the quarterly review for United States.
Why is public DC charging faster but more expensive?
- Because the formula divides energy by charger power: public DC uses high-power fast charging, so 20% to 80% takes about 11 minutes, while a home AC charger takes about 4 hours 15 minutes. But the public DC rate per kWh is higher, so the cost is greater too.