Waveform RMS and Average Values
Full Wave Rectified
Half Wave Rectified
AC Superposed on DC
Periodic Half Sinusoids
Square Wave
Sawtooth Wave
Trapezoidal Wave
The standard formula for calculating the RMS (Root Mean Square) values for a waveform, I(t), is:
Equation for Determining the RMS Value of a Waveform
The tables below show equations for calculating the typical waveform RMS and average values.
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a Sine Wave RMS Calculation |
Sine Wave |
 |
0 |
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a (Full Wave) Rectified Sine Wave RMS Calculation |
Full Wave Rectified Sine Wave |
|
0.637Ipk |
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a Half Wave Rectified Sine Wave RMS Calculation |
Half Wave Rectified Sine Wave |
 |
0.318Ipk |
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a Sine Wave With a DC Offset RMS Calculation |
Direct Current with Superposed Sine Wave |
 |
Idc |
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a Repetitive Half Sinusoid Waveform RMS Calculation |
Half-Sinusoids of Duration T and Frequency f |
 |
(2fIpkT)/ p |
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a Repetitive Square Wave RMS Calculation |
Square Waves of Duration T and Frequency f |
 |
fIpkT |
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a Repetitive Sawtooth Waveform RMS Calculation |
Sawtooth Waveform of Duration T and Frequency f |
 |
0.5fIpkT |
| Current Wave Shape |
Configuration |
IRMS |
IAVG |
 Diagram for a Repetitive Trapezoidal Waveform RMS Calculation |
Trapezoidal Waveform of Frequency f |
 |
fIpk( d+T) |