Please enter all required values.
Formulas & Mathematical Logic
Step 1: Read RMS Voltage, DC Voltage and Peak Voltage from the input fields.
Step 2: Form Factor = RMS Voltage / DC Voltage.
Step 3: Crest Factor = Peak Voltage / RMS Voltage.
Step 4: The calculator displays both ratios as dimensionless electrical waveform factors.
Step-by-Step Example
Example: RMS Voltage = 230 V, DC Voltage = 207 V, Peak Voltage = 325 V.
Step 1: Form Factor = 230 / 207 = 1.111.
Step 2: Crest Factor = 325 / 230 = 1.413.
Step 3: RMS / DC Ratio displays the same value as form factor.
Step 4: Peak / RMS Ratio displays the same value as crest factor.
About This Calculator
Analyze waveform shape using RMS, average DC and peak voltage values.
The CalcBoy Form Factor and Crest Factor Calculator calculates form factor and crest factor from RMS voltage, DC voltage and peak voltage.
Form factor and crest factor are important in electrical waveform analysis because they describe how a waveform behaves beyond a simple voltage reading. RMS voltage tells you the heating or effective value, DC voltage represents average or rectified value, and peak voltage shows the highest instantaneous amplitude. Comparing these values helps identify whether a waveform is close to a sine wave, square wave, rectified waveform or pulse-heavy signal.
Form factor is commonly used in rectifier, charger, transformer, inverter and AC measurement work. Crest factor is especially useful when checking signals with spikes or narrow pulses because high peak voltage can stress components even when RMS voltage appears moderate.
This calculator is useful for electronics repair, oscilloscope measurements, waveform testing, AC power analysis, inverter output checks, rectifier output review and true-RMS meter comparison. For accurate results, use measured RMS, average and peak values from a proper meter or oscilloscope.
Best UseElectrical waveform shape and ratio analysis.
Supported InputsRMS voltage, DC voltage and peak voltage.
Helpful ForAC testing, rectifiers, inverters, power supplies and oscilloscope measurements.
Design ReminderHigh crest factor can reveal hidden peak stress in circuits.
Tip: If RMS value looks safe but crest factor is high, check peak voltage rating of capacitors, diodes, MOSFETs, transformers and insulation.
Frequently Asked Questions
What is form factor?
Form factor is the ratio of RMS voltage to DC or average voltage.
What is crest factor?
Crest factor is the ratio of peak voltage to RMS voltage.
What is the crest factor of a sine wave?
A pure sine wave has a crest factor of about 1.414.
Why is crest factor important?
It shows how high the peak value is compared with RMS value, which helps identify spike-heavy or pulse-heavy waveforms.
Can this calculator be used with current instead of voltage?
The same ratio concept can apply to current waveforms, but this calculator labels inputs as voltage.
What happens if DC voltage or RMS voltage is zero?
The original source logic displays “Not defined” when the calculation is not finite.