Ohm's law · Series · Parallel

Ohm's law and simple DC circuit calculator

Solve voltage, current, resistance, power, and equivalent resistance for simple series or parallel DC circuits.

Built on V = I·R and P = V·I with narrated steps for study.

Everything runs in your browser; inputs are normalized to SI units automatically.

How to use (3 steps)

  1. Choose the mode: single Ohm's law, series, or parallel.
  2. Enter the known values and units. The solved field stays locked and is filled automatically.
  3. Press Compute to see the solved quantities, tables, and narrated steps. Copy URL shares your setup.

Everything runs in your browser; inputs are normalized to SI units automatically.

Inputs

The greyed-out field is solved automatically.

Results

Calculation steps

    FAQ

    How are different units handled?

    Use the unit selector (V/mV/kV, A/mA, Ω/kΩ/MΩ, W/mW/kW). The calculator converts everything to SI internally before solving and formats the output using your chosen units.

    What is the difference between series and parallel?

    In a series circuit the same current flows through every resistor and the voltage splits according to the resistance values. In a parallel circuit the voltage is shared, branch currents split according to the inverse of each resistance, and the currents add up.

    How many resistors can I add?

    You can add up to six resistors to keep the table readable and the calculations stable. For larger networks, break the circuit into smaller series or parallel blocks.

    Can real components differ from these results?

    Yes. Real resistors have tolerance and temperature drift, and wiring or meter resistance can change readings. This tool assumes ideal resistors and provides textbook values for quick checks and study.

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