EV tools

EV charging time calculator

Charging time is the energy you need divided by the power the charger can actually deliver — including the losses that never reach the battery.

How long does it take to charge an EV from 20% to 80%?

Going from 20% to 80% on a 75 kWh pack needs 45.0 kWh in the battery, which means drawing 50.0 kWh at the wall. On a 7.4 kW home charger that is about 6 h 45 min; on a 3.7 kW supply it roughly doubles, and on a domestic 1.4 kW plug it takes most of two days. Real sessions run slightly longer than this because charging tapers as the pack fills and slows further in cold weather.

Charging time by charger power

75 kWh pack, 10% AC charging loss. Times assume constant power and therefore represent a lower bound.
Charger	Power	20 → 80%	10 → 100%
Domestic plug (1.4 kW)	1.4 kW	35 h 43 min	53 h 34 min
Single-phase 16 A (3.7 kW)	3.7 kW	13 h 31 min	20 h 16 min
Home wall charger (7.4 kW)	7.4 kW	6 h 45 min	10 h 8 min
Three-phase (11 kW)	11 kW	4 h 33 min	6 h 49 min
Three-phase 32 A (22 kW)	22 kW	2 h 16 min	3 h 25 min

Adjust for your car and charger

Your inputs

Usable battery capacity

Starting charge

Target charge

Charger power

Scenario: charger

Electricity rate

AC charging loss

Site default: 10%. Energy lost between the socket and the battery pack; measured AC efficiency is typically 85–93%.

Vehicle efficiency

Driving per month

6 h 45 min

to go from 20% to 80% at 7.4 kW

45.0 kWh into the pack, 50.0 kWh drawn from the wall

Calculated from your inputs

Energy to pack: 45.0 kWh
Energy from wall: 50.0 kWh
Charge cost: $9.00
Charging time: 6 h 45 min

Cost per mile

$0.057

Wall energy per mile × rate, so it reflects what the meter records.

Monthly charging cost

$57.14

Based on 1,000 miles per month at 3.5 mi/kWh.

Annual charging cost

$685.71

Distance × wall energy per mile × rate, scaled to 12 average months.

Pack energy and wall energy are different numbers

Your utility bills the wall figure. The extra 10% covers the onboard charger, cable losses and battery thermal management, which is why a 75 kWh pack costs more than 75 kWh to fill.

Method

75 kWh × 60% = 45 kWh added to the pack
45 kWh ÷ 0.9 = 50 kWh drawn from the wall
50 kWh × 0.18 = 9 USD
50 kWh ÷ 7.4 kW = 6.757 hours
Wall energy per mile: 1 ÷ 3.5 mi/kWh ÷ 0.9 = 0.317 kWh/mile
0.317 kWh/mile × 0.18 = 0.057 USD/mile
1000 miles ÷ 3.5 mi/kWh ÷ 0.9 = 317.46 kWh from the wall per average month
317.46 kWh × 0.18 = 57.143 USD per average month
57.143 × 12 average months = 685.714 USD per year

Assumptions

SnapEnergyLab default: 10% AC charging loss between the wall socket and the battery pack (editable). Measured AC charging efficiency typically falls between 85% and 93%.
Charging time is an idealized estimate based on constant charger power.
Real charging may be slower because of vehicle onboard-charger limits, thermal management, battery temperature and charging taper near high state of charge.
Electricity rate of 0.18 USD/kWh (editable).
Vehicle efficiency of 3.5 mi/kWh is measured at the battery pack, so the 10% charging loss is added on top of it to get energy drawn from the wall.

What can change the result?

Whether the vehicle's onboard charger can accept the full supply power — many cap at 7.4 kW on AC
Charging taper above roughly 80% state of charge
Cold weather, which slows charging while the pack warms
Circuit and supply limits, which may derate the charger below its rating
Load management systems that reduce charger power when the house draws heavily

The onboard charger is usually the limit

On AC charging, power is limited by whichever is smaller: the supply, the wall unit, or the vehicle’s onboard charger. Many cars accept a maximum of 7.4 kW single-phase, so installing an 11 kW or 22 kW unit changes nothing for those vehicles. Check the car’s AC charging specification before paying for a higher-power installation.

DC rapid charging bypasses the onboard charger entirely, which is why it is far faster — and why its published speeds cannot be compared with the home figures above.