AC/DC Electrical Calculator
Enter any two values among voltage, current, and resistance. The tool solves the missing value and estimates power for DC or AC circuits.
RMS / Peak / Peak-to-Peak Converter (Sine Wave)
Fill one voltage value and convert the others instantly.
If you work with batteries, power supplies, solar systems, wall outlets, amplifiers, motors, or electronics projects, you regularly switch between AC and DC concepts. This AC DC calculator is designed to make those calculations fast and less error-prone.
What this AC DC calculator can do
- Solve Ohm’s Law: find the missing value from voltage, current, and resistance.
- Estimate power for DC circuits.
- Estimate apparent, real, and reactive power for AC circuits when power factor is known.
- Convert RMS, peak, and peak-to-peak voltage for sine waves.
AC vs DC: quick refresher
DC (Direct Current)
DC current flows in one direction with constant polarity. Typical sources include batteries, USB power adapters, and many solar-storage systems. In basic DC analysis, power is straightforward: P = V × I.
AC (Alternating Current)
AC current changes direction periodically. Grid electricity is AC, commonly 50 Hz or 60 Hz depending on region. For sinusoidal AC, we usually work with RMS values because they represent effective heating/power equivalence to DC.
Core formulas used
Ohm’s Law
- V = I × R
- I = V / R
- R = V / I
Power equations
- DC real power: P = V × I
- AC apparent power: S = V × I (VA)
- AC real power: P = S × PF (W)
- AC reactive power: Q = √(S² − P²) (VAR)
Sine-wave relationships
- VPEAK = VRMS × √2
- VPP = 2 × VPEAK
- VRMS = VPEAK / √2
How to use the calculator correctly
Ohm + Power section
Select DC or AC first. Enter any two of the three base values (voltage, current, resistance), then click Calculate. The tool solves the missing value and displays the relevant power metrics.
For AC, add power factor when available; this gives a realistic real-power estimate for non-resistive loads like motors or switch-mode supplies.
Wave converter section
Enter one voltage format (RMS, peak, or peak-to-peak) and click Convert. The calculator computes the other two values for a sinusoidal waveform.
Practical examples
Example 1: DC load sizing
You have a 24 V system and a heater drawing 6 A. Enter V and I. The calculator returns R = 4 Ω and P = 144 W. This helps choose wire gauge, fuse size, and power supply headroom.
Example 2: AC appliance estimate
You measure 230 V RMS and 5 A RMS on a motor with PF = 0.8. Apparent power is 1150 VA, real power is 920 W, and reactive power is about 690 VAR. This shows why VA can be much higher than watts in inductive loads.
Common mistakes to avoid
- Mixing RMS and peak values in the same equation.
- Ignoring power factor for AC loads.
- Entering more than one inconsistent value in the waveform converter.
- Using ideal equations as a substitute for electrical safety checks.
Safety note
This calculator is for estimation and learning. Real systems include tolerance, harmonics, temperature effects, startup surges, and code requirements. If you are working on mains voltage or high-energy systems, follow local regulations and use qualified electrical guidance.