What This Calculator Does
This tool estimates how long it will take to charge a VinFast electric vehicle based on your charger's power output in kilowatts (kW), the battery capacity in kilowatt-hours (kWh), and the percentage you want to add. It gives you a quick, easy-to-read estimate in both hours and minutes, plus the total energy added.
How to Use It
Enter your battery capacity in kWh (for example, the VinFast VF 8 Eco has roughly an 82 kWh pack). Enter your charger's power in kW — typically 7.4–11 kW for a home AC wallbox or 50–150 kW+ for a DC fast charger. Then set your current charge level and your target charge level as percentages. The calculator returns the estimated time.
The Formula Explained
The math is straightforward: first find the energy you need to add, which is the battery capacity multiplied by the percentage gap divided by 100. Then divide that energy by the charger power to get the time in hours: $$\text{Hours} = \frac{\text{Battery (kWh)} \times \left( \text{Target \%} - \text{Start \%} \right)}{100 \times \text{Charger (kW)}}$$.
Worked Example
Suppose you have an 82 kWh battery, an 11 kW home charger, and you want to go from 20% to 80%. The energy needed is $$82 \times \frac{(80 - 20)}{100} = 49.2 \text{ kWh}.$$ Dividing by 11 kW gives 4.47 hours, or about 268 minutes.
FAQ
Why is real charging slower than this estimate? This is an idealized calculation. Real charging loses energy to heat, and DC fast charging slows down significantly above ~80% to protect the battery, so actual times are usually a bit longer.
Does this work for any EV? Yes — although tuned for VinFast models, the formula is universal. Just enter the correct battery capacity for your vehicle.
What charger power should I use for fast charging? Use the lower of your car's max charge rate and the station's rated power, since charging is limited by whichever is smaller.
