Calculate watts from volts, amps, efficiency, and energy. Review usage, monthly costs, and device totals. Download polished reports and visualize consumption with interactive charts.
Choose a method, enter appliance details, and project energy use, startup load, and cost with one responsive calculator.
This sample table helps you compare common appliance loads and monthly electricity usage using an example tariff of $0.18 per kWh.
| Appliance | Watts | Quantity | Hours/Day | Days/Month | Monthly kWh | Monthly Cost |
|---|---|---|---|---|---|---|
| Refrigerator | 180.00 | 1 | 10.00 | 30 | 54.00 | $9.72 |
| LED TV | 95.00 | 1 | 5.00 | 30 | 14.25 | $2.57 |
| Microwave Oven | 1,200.00 | 1 | 0.50 | 30 | 18.00 | $3.24 |
| Ceiling Fan | 75.00 | 3 | 8.00 | 30 | 54.00 | $9.72 |
| Laptop Charger | 65.00 | 2 | 7.00 | 30 | 27.30 | $4.91 |
Efficiency correction is most useful when derived wattage describes useful output power rather than electrical input power.
Appliance wattage is the rate at which a device uses electrical power while operating. Higher wattage usually means higher energy demand, but total consumption also depends on usage time and quantity.
Power factor matters for many AC appliances, especially motors and compressors. It adjusts apparent power into real power, giving a more realistic wattage estimate than voltage and current alone.
Use efficiency when your starting power value represents useful output, not electrical input. If your appliance label already shows electrical watts, keep efficiency at 100 percent to avoid double adjustment.
Load factor reflects how hard the appliance usually works compared with its maximum rating. A refrigerator or air conditioner often cycles, so average operating watts can be lower than nameplate watts.
Many appliances with motors need extra power at startup. Surge watts help you size circuits, generators, or inverters more safely than using normal running watts alone.
Yes. It multiplies projected energy consumption by your tariff per kWh. Enter a realistic daily run time and monthly operating days for better cost estimates.
Choose the measured energy method. Enter total kWh and the number of hours over which that energy was recorded. The calculator converts that reading into average watts.
They are estimates. Actual wattage can vary with voltage swings, thermostat cycling, motor load, ambient temperature, and equipment condition. For exact values, verify with a watt meter.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.