Current through a 100Ω resistor at 3.3V
Worked answer for 3.3V applied across a 100Ω resistor, using Ohm's law (I = V/R) and power (P = V²/R).
Current 33.0 mA 3.3V ÷ 100Ω · dissipates 109 mW
| Voltage (V) | 3.3 V |
| Resistance (R) | 100Ω |
| Current I = V / R | 33.0 mA |
| Power P = V² / R | 109 mW |
Driving 3.3V through 100Ω gives 33.0 mA of current (I = V/R) and the resistor must dissipate 109 mW of heat (P = V²/R). Pick a resistor power rating comfortably above that figure.
Different values? Enter any two of voltage, current, resistance or power in the interactive tool:
Open the Ohm's Law Calculator →Disclaimer: This is a reference estimate using ideal Ohm's law. Real components have tolerance and self-heating; verify against your part's datasheet and power rating before building.