Electrical fundamentalsMVP
Power dissipation
Compute resistive (real) power from any two of voltage, current, and resistance.
Inputs
Result
Enter values and calculate to see the result.
Interpretation
Choose which two quantities you know. All three forms (P = V·I, I²·R, V²/R) are algebraically equivalent for an ohmic device.
Formula
P = V · I = I² · R = V² / R
Three equivalent forms for an ohmic device.
Variables
| Symbol | Variable | Unit |
|---|---|---|
| P | Power | W |
| V | Voltage | V |
| I | Current | A |
| R | Resistance | Ω |
Assumptions & validity
This tool assumes:
- Resistive (real) power; no reactive/AC phase effects.
- DC / steady-state, ohmic device.
Worked example
A device drops 3.3 V while drawing 100 mA.
P = 3.3 V × 0.10 A = 0.33 W