SOLAR · CALCULATOR

EV charging time calculator

Free EV charging time calculator: get estimated charging time from battery capacity, starting charge, target charge, charger output and efficiency.

Written by Chameera Sampath · Not yet reviewed by a licensed electrician. See the methodology.

US (NEC) only · NFPA 70 / NEC — locally adopted editionDefaults are US values. Verify the locally adopted NEC edition and project data.Official reference ↗

Project inputs

Measurements

Battery capacity

kWh

Starting charge

Target charge

Charger output

Efficiency

Updates as inputs change. Unit changes preserve the same physical values.

THE MATH BEHIND THE ANSWER

Method & assumptions

t = capacity × (target − start) / (100 × power × η)

Constant power estimate; taper, battery temperature and vehicle limits extend charging time.

Results do not check every aspect of an electrical installation. The calculators follow US (NEC) practice only; a regional preset changes defaults such as voltage and units, and no result certifies NEC compliance.

Sources and validation →

Worked example

Battery capacity: 60 kWh · Starting charge: 20 % · Target charge: 80 % · Charger output: 7.2 kW · Efficiency: 90 %

Estimated charging time: 5.556 h

This example uses the stated inputs; results for the entered values appear above.

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Estimating and invoicing tool

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