Enter Current Data
Formula used
| Case | RMS relationship |
|---|---|
| Sine wave | IRMS = Ipeak / √2 |
| Square wave | IRMS = Ipeak |
| Triangle or sawtooth | IRMS = Ipeak / √3 |
| Rectangular pulse | IRMS = Ipeak × √D |
| Custom samples | IRMS = √[Σ(I²) / n] |
| Ohm relationship | IRMS = VRMS / Z |
| Single-phase real power | I = P / (V × PF × η) |
| Three-phase real power | I = P / (√3 × VLL × PF × η) |
| AC plus DC | Itrue,RMS = √(IAC,RMS² + IDC²) |
How to use this calculator
Select the calculation mode matching your available electrical data. Enter values with their units. Then choose the desired result precision.
Use waveform mode for peak, average, or sampled currents. Use power modes for electrical load estimates. Review warnings before applying results.
- Choose a waveform or electrical calculation mode.
- Enter all required values and correct units.
- Add optional resistance for power estimation.
- Press the calculation button.
- Copy, print, or export the results.
RMS, average, and peak current
RMS current represents equivalent resistive heating. Peak current shows the largest instantaneous magnitude. Average current describes a waveform’s mean behavior.
These values differ for most alternating waveforms. Distorted currents require true RMS processing. Sample mode supports those practical measurements accurately.
Example data table
| Example | Inputs | Expected RMS current |
|---|---|---|
| Sine wave | Peak = 10 A | 7.0711 A |
| Square wave | Peak = 10 A | 10.0000 A |
| Triangle wave | Peak = 10 A | 5.7735 A |
| 50% pulse | Peak = 10 A, D = 0.5 | 7.0711 A |
| Ohm relationship | 120 V, 10 Ω | 12.0000 A |
| Single phase | 1000 W, 230 V, PF 0.9 | 4.8309 A |
| Three phase | 10 kW, 400 V, PF 0.9 | 16.0375 A |
Important assumptions and limits
Power calculations assume balanced and steady electrical operation. Harmonics can increase conductor heating significantly. Confirm results against applicable engineering standards.
Sample accuracy depends on timing and measurement quality. Full cycles improve RMS reliability. Safety decisions require qualified professional review.
Frequently asked questions
What does RMS current mean?
RMS means root mean square. It represents equivalent heating current. A matching DC current produces similar resistive heating.
Why is sine-wave RMS lower than peak?
A sine wave reaches its peak briefly. Most values remain below that peak. Therefore RMS equals peak divided by square root two.
Can this calculator handle distorted waveforms?
Yes, use the custom sample mode. Enter measured values or timed pairs. The calculator computes true RMS from those samples.
What is AC-only RMS?
AC-only RMS removes the waveform’s mean component. It describes variation around the average. Total RMS includes both AC and DC.
What is crest factor?
Crest factor divides absolute peak by RMS. High values indicate sharp current peaks. Equipment may require extra peak-current capability.
What is form factor?
Form factor divides RMS by average absolute current. It describes waveform shape. A sine wave has about 1.11 form factor.
How should timestamps be entered?
Enter one time and current pair per line. Use seconds for time values. Times must increase without duplicates.
Why does duty cycle affect pulse RMS?
Shorter pulses conduct for less total time. Heating depends on squared current over time. RMS therefore scales with square root duty.
Which three-phase voltage should I enter?
Select line-to-line for common system voltage ratings. Select line-to-neutral when that voltage is known. The formula changes automatically.
Can results size wires or protective devices?
The calculator provides analytical estimates only. Codes require additional derating and safety factors. Consult qualified electrical professionals before final sizing.