Ohm's Law and Electrical Power Calculator
Calculate voltage, current, resistance and power for ideal DC resistive circuits from any two known values, with worked steps and a printable report. Runs locally in your browser.
Ohm's Law and Electrical Power Calculator
Select two known electrical quantities to calculate voltage, current, resistance and power for ideal DC resistive circuits.
Calculation setup
Results
Enter both values for the selected known pair to see a result.
Worked calculation
Enter valid values to see the worked calculation.
Formula
R = V ÷ I, P = V × I (selected)
I = V ÷ R, P = V² ÷ R
I = P ÷ V, R = V² ÷ P
V = I × R, P = I² × R
V = P ÷ I, R = P ÷ I²
V = √(P × R), I = √(P ÷ R)
Ohm's law and the power law together relate voltage (V), current (I), resistance (R) and power (P) for ideal DC resistive circuits.
Scope, assumptions and safety
For ideal DC resistive calculations only. Not for AC or reactive loads, mains installation design, cable sizing, protective-device selection, compliance work, or safety-critical decisions.
Never work on live circuits. Verify real-world results against measurements, component data and qualified professional advice.
Local processing
All calculations run locally in your browser. This tool does not upload or store the values you enter.
Assumptions and limitations
This tool is for ideal, steady-state DC resistive circuits only. It is not intended for AC or reactive loads, mains installation design, cable sizing, protective-device selection, compliance work or safety-critical decisions. Component tolerances, temperature effects, wiring resistance and non-ideal source behaviour are not modelled. Results are informational and should be independently checked for regulated, laboratory, engineering or safety-critical work.
Related tools
Ohm's Law and Electrical Power Calculator
Ohm's Law and Electrical Power Calculation Report
Generated 20 July 2026 at 02:57
Conversion summary
Formulas
V = I x R. I = V / R. R = V / I. P = V x I. P = I^2 x R. P = V^2 / R.
Worked calculation
- Enter both values for the selected known pair to see the worked calculation.
Assumptions and limitations
This tool is for ideal, steady-state DC resistive circuits only. It is not intended for AC or reactive loads, mains installation design, cable sizing, protective-device selection, compliance work or safety-critical decisions. Component tolerances, temperature effects, wiring resistance and non-ideal source behaviour are not modelled. Results are informational and should be independently checked for regulated, laboratory, engineering or safety-critical work.
Local processing
All calculations run locally in your browser. This tool does not upload or store the values you enter.
Informational use and independent verification
Never work on live circuits. Verify real-world results against measurements, component data and qualified professional advice.