Energy (Wh) = (mAh x V) / 1000 / Efficiency
Enter your phone's battery capacity (found in specs), the nominal voltage (typically 3.7V for lithium-ion batteries), charger efficiency (usually 80-90%), how often you charge, and your electricity rate. The calculator computes the actual energy drawn from the wall per charge and projects costs daily, monthly, and yearly.
A Phone Charging Cost Calculator estimates how much electricity your smartphone uses and what it costs to charge it. While the cost per charge is typically very small (fractions of a cent), it adds up over a year -- especially if you have multiple devices in your household.
Understanding your charging costs can help you appreciate the energy efficiency of modern smartphones compared to other household appliances, and gives you a realistic picture of the true cost of keeping your devices powered.
Start by finding your phone's battery capacity in milliamp-hours (mAh) -- this is listed in your phone's specifications or settings. The default voltage of 3.7V works for most modern smartphones with lithium-ion batteries.
Set the charger efficiency (typically 80-90% for modern chargers; fast chargers may be slightly less efficient). Enter how many times you charge your phone per day and your local electricity rate per kWh. The calculator will show you the cost breakdown from per-charge to yearly totals.
No charger converts 100% of wall power into stored battery energy. Some energy is lost as heat during charging. The efficiency percentage represents how much of the electricity drawn from the outlet actually makes it into your phone's battery.
Standard Chargers (5W)
Typically 85-90% efficient. These older, slower chargers waste less energy as heat and are the most efficient option for overnight charging.
Fast Chargers (18W-65W+)
Typically 75-85% efficient. The higher power delivery generates more heat, reducing overall efficiency. However, the convenience trade-off is minimal in cost terms.
Important Note
This calculator provides estimates based on typical charging conditions. Actual costs may vary based on battery health, temperature, charger type, and whether you charge from 0% or top up partially. The electricity rate can be found on your utility bill.