What is Ohm's Law?

Ohm's Law is one of the first things you learn in electronics, and it never stops being useful. It describes the relationship between three quantities that show up in virtually every circuit: Voltage (V), Current (I), and Resistance (R).

The whole thing boils down to one formula: `V = I × R`

The Components Explained

• Voltage (V) is measured in Volts. It's the electrical potential difference between two points — the "pressure" that drives charge through a circuit. No voltage, no flow.
• Current (I) is measured in Amperes (A). It's how much charge is actually moving through the conductor per second — the flow rate, essentially.
• Resistance (R) is measured in Ohms (Ω). It's how much the conductor pushes back against that flow. Higher resistance means less current for a given voltage.
• Power (P) is measured in Watts (W). The calculator also figures this out for you using `P = V × I`. It tells you how fast electrical energy is being transferred — which matters a lot when you're sizing components.

How This Calculator Helps

Pick the value you want to solve for — Voltage, Current, or Resistance — then enter the two values you already know. The calculator finds the missing one instantly, and also shows the resulting power. It's the kind of thing you'd otherwise reach for scratch paper to figure out, and it comes up constantly when you're designing circuits or troubleshooting something that isn't behaving.

Hobbyists, engineering students, and working electricians all run these calculations regularly. Having a reliable tool for it just saves time.