Enter the base bias voltage (volts), the base-emitter volt drop (volts), and the base input resistor (ohms) into the calculator to determine the Transistor Base Current.

## Transistor Base Current Formula

The following formula is used to calculate the Transistor Base Current.

Ib = ( Vb - Vbe) / Rb
• Where Ib is the Transistor Base Current (amps)
• Vb is the base bias voltage (volts)
• Vbe is the base-emitter volt drop (volts)
• Rb is the base input resistor (ohms)

To calculate the transistor base current, subtract the base-emitter volt drop from the base bias voltage, then divide by the base input resistor.

## How to Calculate Transistor Base Current?

The following example problems outline how to calculate Transistor Base Current.

Example Problem #1

1. First, determine the base bias voltage (volts). In this example, the base bias voltage (volts) is determined to be 18 .
2. Next, determine the base-emitter volt drop (volts). For this problem, the base-emitter volt drop (volts) is measured to be 17 .
3. Next, determine the base input resistor (ohms). In this case, the base input resistor (ohms) is found to be 9.
4. Finally, calculate the Transistor Base Current using the formula above:

Ib = ( Vb – Vbe) / Rb

Inserting the values from above and solving yields:

Ib = ( 18 – 17) / 9 = .11 (amps)

Example Problem #2

Using the same method as above, determine the variables required by the formula. For this example problem, these are:

base bias voltage (volts) = 8

base-emitter volt drop (volts) = 7

base input resistor (ohms) = 3

Enter these given values into the calculator or above yields:

Ib = ( 8 – 7) / 3 = .333 (amps)