Quick answer
Charging time = battery capacity × (target − start) ÷ (charger power × efficiency). Charging a 60 kWh battery from 10% to 80% on an 11 kW charger at 90% efficiency takes 4.24 hours and draws 46.67 kWh.
Enter usable capacity, start and target charge, charger power and efficiency. The calculator returns the time and the energy drawn. Use this ev charge time calculator to check your own figures.
Related tools: Battery Charge Time Calculator: Hours to charge a battery from a charger current. EV Charging Cost Calculator: Cost of charging between two battery levels. EV Range Calculator: Driving range from battery capacity and energy consumption.
How to use the EV Charge Time Calculator
- Enter usable battery capacity (kWh) (above 0).
- Enter starting charge (%) (between 0 and 100).
- Enter target charge (%) (between 0 and 100).
- Enter charger power (kW) (above 0).
- Enter charging efficiency (%) (between 0 and 100). It starts at 90.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Usable battery capacity | A number, in kWh | > 0 |
| Starting charge | A number, in % | ≥ 0, ≤ 100 |
| Target charge | A number, in % | ≥ 0, ≤ 100 |
| Charger power | A number, in kW | > 0 |
| Charging efficiency | A number, in % | > 0, ≤ 100, starts at 90 |
Formula and method
Formula
time = capacity × (target − start) ÷ (charger power × efficiency)
IEEE-754 double precision; shown to the decimals indicated.
Assumes a constant charging rate; real DC fast charging tapers above about 80%.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Usable battery capacity = 60; Starting charge = 10; Target charge = 80; Charger power = 11; Charging efficiency = 90.
| Result | Value |
|---|---|
| Charging time | 4.24 h |
| Energy drawn from the grid | 46.67 kWh |
Example 2
Inputs: Usable battery capacity = 75; Starting charge = 20; Target charge = 100; Charger power = 150; Charging efficiency = 90.
| Result | Value |
|---|---|
| Charging time | 0.44 h |
| Energy drawn from the grid | 66.67 kWh |
Example 3
Inputs: Usable battery capacity = 40; Starting charge = 0; Target charge = 100; Charger power = 7.4; Charging efficiency = 85.
| Result | Value |
|---|---|
| Charging time | 6.36 h |
| Energy drawn from the grid | 47.06 kWh |
The first line is the headline result (charging time). Below it the eV Charge Time Calculator lists energy drawn from the grid, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
The calculation
Energy to add: 60 × 0.70 = 42 kWh. Effective power: 11 × 0.90 = 9.9 kW. Time: 42 ÷ 9.9 = 4.24 hours, about 4 hours 15 minutes.
Why real charging takes longer
Charging slows as the battery fills and in cold weather, and the car's onboard charger may limit AC power below the wallbox rating. A fast DC charger tapers after about 80%, which is why charging to 80% is so common. Treat the figure as a planning estimate.
How the result changes with usable battery capacity
Holding every other input at the first worked example, this table changes only usable battery capacity. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Usable battery capacity | Charging time | Energy drawn from the grid |
|---|---|---|
| 30 | 2.12 h | 23.33 kWh |
| 60 | 4.24 h | 46.67 kWh |
| 120 | 8.48 h | 93.33 kWh |
| 240 | 16.97 h | 186.67 kWh |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Target charge: entering "40" shows "The target must be above the starting charge." beside that field and no result.
- Charger power: entering "0" shows "Charger power must be greater than 0." beside that field and no result.
Choosing between the EV Charge Time Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Battery Charge Time Calculator](/energy/battery-charge-time/) | battery capacity, charger current and charging efficiency | Charge time |
| [EV Charging Cost Calculator](/automotive/electric-vehicle-charging-cost-calculator/) | usable battery capacity, starting charge and target charge | Charging cost |
| [EV Range Calculator](/automotive/ev-range-calculator/) | usable battery capacity, energy consumption and consumption unit | Range |
| [Time Converter](/converters/time-converter/) | value, from and to | Day (d) → Hour (h) |
| [Time Duration Calculator](/time/time-duration-calculator/) | start time and end time | Duration |
Background: vehicle sizing and speed
A taller tyre travels farther per revolution, so the speedometer reads low and the effective gear ratio becomes numerically lower; a shorter tyre does the opposite. True speed is roughly the speedometer reading times the new tyre diameter divided by the old one. Verify with GPS over a known distance before changing parts.
Assumptions and limitations
- Charging slows near full
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for target charge and charger power to confirm this.
Frequently asked questions
What charger power can my car accept?
It is limited by the onboard charger; check the car's specification.
Does a bigger wallbox charge faster?
Only up to the car's limit.
Why not 100%?
The last 20% takes disproportionately long.
What does the EV Charge Time Calculator calculate?
Time to charge between two battery levels. It returns Charging time and Energy drawn from the grid.
What formula does the EV Charge Time Calculator use?
time = capacity × (target − start) ÷ (charger power × efficiency). Assumes a constant charging rate; real DC fast charging tapers above about 80%.
What do I need to enter in the eV Charge Time Calculator?
You enter Usable battery capacity (kWh), Starting charge (%), Target charge (%), Charger power (kW) and Charging efficiency (%).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Charging slows near full.
What is an example of a eV Charge Time result?
With usable battery capacity 60, starting charge 10, target charge 80, charger power 11 and charging efficiency 90, the charging time is 4.24 h.
Where does the method come from?
The method follows: OpenStax, University Physics Volume 2 (Rice University): electricity, circuits and thermodynamics: electric power and energy (E = P × t); Real charging slows near full charge and varies with temperature and charger, so treat the result as a lower bound.
Related calculators
- Battery Charge Time Calculator — Hours to charge a battery from a charger current.
- EV Charging Cost Calculator — Cost of charging between two battery levels.
- EV Range Calculator — Driving range from battery capacity and energy consumption.
- Time Converter — Convert seconds, minutes, hours, days, weeks, months and years.
- Time Duration Calculator — Elapsed time between two clock times, including across midnight.
- Time Card Calculator — Total hours, overtime and gross pay from daily start and end times.
- Time Dilation Calculator — Dilated time for a clock moving at relativistic speed.
- Mining Time Estimate Calculator — Expected time to find a proof-of-work block.
- Reading Time Calculator — Time to read a text at a reading speed.
Sources
- OpenStax, University Physics Volume 2 (Rice University): electricity, circuits and thermodynamics: electric power and energy (E = P × t)
- Real charging slows near full charge and varies with temperature and charger, so treat the result as a lower bound
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.