🔌 RMS to Watts Converter
Compute AC power from RMS measurements in multiple scenarios.
Helpful for audio engineering, electrical design, and verifying lab measurements.
Speaker impedance or circuit load.
Power: 1,800 W
Implied Current: 15 A RMS
How to Use This Calculator
Select your known values
Choose the calculation mode based on what RMS values you measured.
Enter the measurements
Provide voltage, current, resistance, and power factor as required.
Read the real power
Use the computed watts to size equipment, estimate heat loss, or balance loads.
Formula
P = Vrms² ÷ R
P = Irms² × R
P = Vrms × Irms × PF
Where PF (power factor) is 1 for purely resistive loads.
Use the formula breakdown to confirm the calculation logic or perform the conversion manually if needed.
Full Description
RMS measurements represent effective voltage and current in AC circuits. Converting them to watts lets you quantify real power—the energy actually consumed or dissipated as heat.
Choose the formula that matches the measurements you have. Audio engineers often know speaker impedance (resistance), while industrial electricians use RMS voltage, current, and power factor from meters.
Keep in mind that inductive or capacitive loads reduce power factor; include it for accurate real power, especially in AC power systems.
Frequently Asked Questions
What is power factor?
It describes phase difference between voltage and current. For purely resistive loads it is 1; for motors it may drop below 1.
Can this calculator find RMS voltage from watts?
Yes. In voltage/resistance mode the reverse values display below the main result.
Does it handle DC?
For DC circuits, RMS equals the DC value. Use the voltage/resistance or current/resistance modes directly.
What units should I use?
Voltage in volts RMS, current in amps RMS, resistance in ohms, power factor between 0 and 1.