⚡ AC Wattage Calculator
Calculate AC power consumption
Enter RMS voltage (e.g., 120V for US, 230V for Europe)
1.0 for resistive loads, 0.8-0.9 for motors, 0.5-0.7 for heavily inductive loads
How to Use This Calculator
Enter RMS Voltage
Input the RMS (Root Mean Square) voltage of your AC circuit. Common values: 120V (US), 230V (Europe), 240V (UK/Australia).
Enter RMS Current
Input the RMS current flowing through the circuit in Amperes. This is typically measured with an ammeter or clamp meter.
Enter Power Factor
Input the power factor (0 to 1). Use 1.0 for purely resistive loads like heaters and incandescent bulbs. Use 0.8-0.9 for motors, and 0.5-0.7 for heavily inductive loads.
Calculate
Click the "Calculate AC Power" button to get real power (wattage), apparent power (VA), and reactive power (VAR).
Formula
P = V × I × cos(φ) = V × I × Power Factor
Where:
- P = Real Power / Wattage (Watts, W)
- V = RMS Voltage (Volts)
- I = RMS Current (Amperes)
- cos(φ) = Power Factor (dimensionless, 0 to 1)
- φ = Phase angle between voltage and current
Additional Formulas:
- Apparent Power (S) = V × I (VA - Volt-Amperes)
- Reactive Power (Q) = V × I × sin(φ) (VAR - Volt-Amperes Reactive)
Example Calculation:
For a motor operating at 230V, 5A, with a power factor of 0.85:
Real Power = 230 × 5 × 0.85 = 977.5 W
Apparent Power = 230 × 5 = 1,150 VA
Reactive Power = 230 × 5 × sin(arccos(0.85)) = 605.7 VAR
About AC Wattage Calculator
The AC Wattage Calculator determines the real power consumption in alternating current (AC) circuits. Unlike DC circuits where power is simply voltage times current, AC power calculation must account for the power factor, which represents the phase difference between voltage and current waveforms. This calculator helps you understand actual energy consumption and electrical billing.
When to Use This Calculator
- Electrical Engineering: Calculate power consumption in AC circuits and electrical systems
- Energy Management: Estimate electricity costs and energy usage for appliances and equipment
- Motor Sizing: Determine actual power requirements for motors and industrial equipment
- Circuit Design: Size wires, breakers, and protective devices based on real power consumption
- Energy Audits: Analyze power consumption and efficiency of electrical systems
Why Use Our Calculator?
- ✅ Complete Power Analysis: Calculates real power, apparent power, and reactive power
- ✅ Power Factor Awareness: Accounts for phase differences in AC circuits
- ✅ Accurate Billing: Get real power consumption for electricity cost estimation
- ✅ Free Tool: No registration or payment required
- ✅ Easy to Use: Simple interface for quick calculations
Common Applications
Home Appliances: Calculate actual power consumption of refrigerators, air conditioners, washing machines, and other household appliances to estimate electricity bills and optimize energy usage.
Industrial Motors: Determine real power requirements for electric motors, which typically have power factors between 0.8 and 0.9, helping in proper motor sizing and energy management.
Electrical System Design: Size circuit breakers, wires, and transformers based on real power consumption rather than just apparent power, ensuring safe and efficient electrical installations.
Tips for Best Results
- Always use RMS values for voltage and current in AC circuits
- Power factor of 1.0 means purely resistive load (no phase difference)
- Lower power factors indicate more reactive power and less efficient energy usage
- Motors typically have power factors between 0.7 and 0.9
- Real power (W) is what you pay for in electricity bills, not apparent power (VA)
Frequently Asked Questions
What is the difference between real power and apparent power?
Real power (W) is the actual energy consumed and is what you pay for on your electricity bill. Apparent power (VA) is the product of voltage and current but doesn't account for power factor. Real power = Apparent power × Power factor.
Why is power factor important?
Power factor indicates how efficiently electrical power is being used. A lower power factor means more reactive power is required, which can increase energy costs and require larger electrical infrastructure. Utilities may charge penalties for low power factors.
What is a good power factor?
A power factor close to 1.0 (or 100%) is ideal, indicating efficient power usage. Most utilities require power factors above 0.85-0.90. Power factors below 0.70 are considered poor and may result in penalties.
How do I find the power factor of a device?
You can measure power factor using a power quality meter or clamp meter with power factor measurement. Alternatively, you can estimate: resistive loads (heaters, bulbs) = 1.0, motors = 0.7-0.9, heavily inductive loads = 0.5-0.7.
Can I use this for DC circuits?
For DC circuits, power is simply P = V × I, and power factor is always 1.0. While you can use this calculator with power factor = 1.0, a simple DC power calculator would be more appropriate.
What is reactive power?
Reactive power (VAR) is the power that oscillates between the source and load without being consumed. It's needed to establish magnetic fields in inductive loads but doesn't contribute to actual work. High reactive power increases apparent power and system losses.