LM317 Calculator

Find the output voltage of an LM317 regulator.

Output voltage (V) 5

Formula: Vout = 1.25 * (1 + R2 / R1)

Step-by-step with your numbers:

1. Values used:

2. R1 = 240 ohm

3. R2 = 720 ohm

5. Output voltage = 5V

Did we solve your problem today?

The LM317 adjustable regulator sets its output with two resistors.

The math behind it

Vout = 1.25 x (1 + R2/R1). The 1.25 V is the regulator's reference voltage.

R1 240, R2 720 gives 5 V.

What is R1 usually?

240 ohms is the typical recommended value.