Solve for Current: 12V, 100Ω Resistor
Enter any two of voltage, current, resistance, and power, and the page fills in the other two.
🔒 Processed entirely in your browser — nothing you enter here is ever uploaded.
The result appears on this page after you run the tool. Nothing you enter is uploaded.
Result
About this tool
This page opens the Ohm's law calculator with a 12V supply and a 100Ω resistor already filled in — the result below is live, computed the moment the page loads, not a static example.
Solving for current is the most common Ohm's law question when you know the supply voltage and the resistor you are about to place in a circuit: I = V / R gives 12V / 100Ω = 0.12A, or 120mA. The calculator also derives power (P = VI), which here comes out to 1.44W — enough that a standard quarter-watt (0.25W) resistor would overheat, so this combination calls for at least a half-watt part.
Change either field above and the current, resistance, voltage and power all re-solve together — the tool works from any two known values, not just voltage and resistance, so it doubles as a check for whatever pair of numbers you actually have on hand.
Example. Voltage 12 V and resistance 4 Ω return current 3 A and power 36 W. Voltage 9 V and current 20 mA return resistance 450 Ω and power 180 mW.
Limit. At least two of voltage, current, resistance, and power must be strictly positive. A later power-and-resistance step overwrites current and voltage when power is also filled in.