Enter any two of voltage, current, resistance and power to get the other two, with a recommended resistor power rating.
Ohm’s law links the voltage (V), current (I) and resistance (R) of a resistor: V = I × R, and power is P = V × I. Pick the two values you know; the calculator returns the other two and the power rating the resistor needs so it doesn’t burn (at least twice the dissipated power).
Cover what you want to find and read the rest: V = I × R, I = V / R, R = V / I. Power: P = V × I.
