LM317 Adjustment Calculator

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This page allows you to calculate the size/value or resistor required to run an LM317 at the correct voltage.
Click on any of the links at the top of the page to reveal (or hide) more information about this calculator.


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Output Voltage of the circuit.
Value of Resistor between Vout and Vadj pins, typically specified as 220Ω
Value of Resistor between Vadj and circuit ground.


V = 1.25 * (1 + R2 / R1)


  1. Enter a value into each text-box in the form below.
  2. Choose appropriate unit-sizes for each value from each drop-down list.
  3. Hit the ENTER or RETURN key on your keyboard, or press the 'CalcResult' button below the input fields.
  4. A results area will appear at the bottom of the page, showing the required resistance value.
  5. Press the 'Clear Results' button if you wish to discard the current results list, otherwise further calculations will be added to the bottom of the current results list.

See Also:

Enter Data Here
Optional Data
Basic LM317 circuit diagram
LM317 circuit diagram


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