How to use (3 steps)
- Choose the mode: single Ohm's law, series, or parallel.
- Enter the known values and units. The solved field stays locked and is filled automatically.
- 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.
Resistors in series
Resistors in parallel
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.
What is a good first check after I enter values?
Confirm the selected units first, then check whether the solved value satisfies V = I·R or P = V·I before moving on to the circuit tables.
How to read the circuit summary
Single-value mode
Check the solved quantity first, then verify the matching power or Ohm's law relation underneath. This is the fastest way to catch a unit mistake. For another formula-first physics workflow, compare with Snell's Law, Ideal Gas Law, and Simple Harmonic Motion.
Series mode
In series, the same current should appear everywhere. Read the table by checking whether the voltage drops add back up to the supply after rounding.
Parallel mode
In parallel, the branch voltages stay the same while the currents split. The total current should match the sum of the branch currents.
Equivalent resistance
Use R_eq to compare the whole network with a single resistor. For a parallel circuit it should always be lower than the smallest branch resistance.
Share and study workflow
Copy the URL when you want to reopen the same inputs later. Use the step list and summary cards together if you are preparing notes or checking a homework solution.
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