Phone Charging Cost Calculator

About this calculator

The energy a phone battery actually stores is its capacity in milliamp-hours converted to watt-hours using its nominal voltage: Energy (Wh) = (Capacity in mAh / 1000) × Voltage (V), then divided by charging efficiency to account for the energy lost as heat during charging (chargers typically run somewhere around 80–90% efficient). Multiplying that per-charge energy by how many times you charge per day and by your electricity rate gives the running cost.

Because phone batteries are small — typically in the range of 10–20 Wh — the actual electricity cost of charging one, even daily over a full year, is usually just a small fraction of a typical electricity bill, which is why this kind of calculation is mostly useful as a curiosity or a way to compare charging habits and rates rather than a meaningful budgeting line item. This calculator takes your battery capacity, voltage, daily charge count and electricity rate and estimates the cost per charge and per year.