Electricity Calculator
Calculate electrical power, energy consumption, and utility costs with our comprehensive electrical calculator
Use 1.0 for resistive loads (heaters, incandescent); 0.8-0.95 for motors and electronics
Power
1.200 kW
Current
10000 mA
Voltage
0.120 kV
Resistance
0.012 kΩ
How it works
An electricity calculator relates power, voltage, current, and energy. Power (watts) is voltage times current; energy used over time is power times hours, measured in kilowatt-hours — the unit your utility bills.
Power and energy
P = V × I Energy (kWh) = (watts ÷ 1000) × hours
- P
- power in watts
- V, I
- voltage and current
- kWh
- energy used
Worked example
- A 1,500 W heater
- Runs 3 hours
- Energy = (1500 ÷ 1000) × 3
4.5 kWh consumed.
Good to know
- Watts measure the rate of use; kilowatt-hours measure total energy (rate × time).
- Multiply kWh by your rate to get cost.
- Power can also be found as P = I²R or P = V² ÷ R.
Related Calculators
Frequently Asked Questions
What is a kilowatt-hour (kWh) and how is it calculated?
A kilowatt-hour (kWh) is a unit of energy equal to using 1,000 watts for one hour. To calculate kWh, multiply power in kilowatts by time in hours. For example, a 100-watt bulb (0.1 kW) running for 10 hours uses 1 kWh. This is the standard unit utilities use for billing.
How do I calculate my electricity costs?
To calculate electricity costs: 1) Find your appliance's wattage, 2) Calculate daily usage hours, 3) Convert to kWh (watts × hours ÷ 1000), 4) Multiply by your electricity rate ($/kWh). For monthly costs, multiply by 30. Our calculator automates this process for accurate results.
What's the difference between watts, volts, and amps?
Volts (V) measure electrical pressure, amps (A) measure electrical current flow, and watts (W) measure electrical power. They're related by the formula: Watts = Volts × Amps. Think of it like water: volts are water pressure, amps are flow rate, and watts are total water power.
How can I reduce my electricity consumption?
Key strategies: 1) Replace incandescent bulbs with LEDs (75% savings), 2) Unplug phantom loads (5-10% savings), 3) Use smart power strips, 4) Optimize HVAC settings (3% per degree), 5) Upgrade to ENERGY STAR appliances, 6) Seal air leaks, 7) Use off-peak rates if available.
What wire size do I need for my electrical project?
Wire size depends on amperage and distance. For 15A circuits, use 14 AWG; for 20A, use 12 AWG; for 30A, use 10 AWG. Longer runs require larger wire to prevent voltage drop. Always consult local codes and consider hiring a licensed electrician for safety.
How do I use Ohm's Law for electrical calculations?
Ohm's Law states V = I × R (Voltage = Current × Resistance). Related formulas: Power (W) = V × I, Current (I) = V/R, Resistance (R) = V/I. Use these to calculate any electrical value when you know two others. Our calculator handles these conversions automatically.
What's the difference between AC and DC power?
AC (Alternating Current) reverses direction periodically and is used in homes (120V/240V in US). DC (Direct Current) flows in one direction and is used in batteries, electronics, and solar panels. AC is easier to transmit over long distances, while DC is more efficient for electronic devices.