# Find amperage, voltage or resistance

This calculator will help you calculate the amperage (I), voltage (U) and resistance (R) in a circuit. The calculation is based on Ohm’s law. Select a value and calculate it according to known parameters.

### Determine current

**Voltage (U) Volt:**

**Resistance (R) Ohm:**

### Determine the resistance value

**Voltage (U) Volt:**

**Amperage (I) Amp:**

### Find voltage

**Current (I) Ampere:**

**Resistance (R) Ohm:**

## Definitions and formulas

**Amperage**— a physical quantity equal to the ratio of the amount of charge passing through a surface over a period of time to the value of this period of time.- Electrical
**resistance**— physical quantity characterizing the property of a conductor to impede the passage of electric current and equal to the ratio of the voltage at the ends of the conductor to the strength of the current flowing through it **Voltage**— it is an electromotive force that pushes free electrons from one atom to another in the same direction