Watt‑hour Calculator
Energy consumption
Enter voltage, current and operating time; energy appears live.
Energy
How to use this calculator
Energy is power times time, and power is voltage times current: Wh = V × I × hours. Enter the voltage, the current (A or mA) and the operating time in hours, and the energy appears live in watt‑hours (Wh), kilowatt‑hours (kWh) and joules (J), with the power (W) shown for reference. For example, a 12 V, 1 A load running for 10 hours uses 120 Wh, which is 0.12 kWh or 432,000 J.
What it means in a real circuit
This is how you work out how much energy a load actually consumes — the number you need to size a battery, a generator, or a solar array, and the same basis your electricity bill uses (in kWh). Use it to compare appliances, budget a campsite's power use, or check whether your battery has enough watt‑hours to run a device for the time you need.