LED Resistor Calculator

Resistors are key components in Light Emitting Diode (LED) circuits, protecting the LEDs from receiving too much current, which can damage or shorten the life of the LEDs. This tutorial will explain how to calculate the value of the resistor needed in a series LED circuit. This knowledge is essential in the field of electronics, a branch of physics.

LED Series Resistor Calculator
LED Resistor Calculator Results
Resistance =
Recommended Resistor (Nearest lower 10%) =
Recommended Resistor (Nearest Higher 10%) =
Resister Wattage = Watts

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Example Formula

The resistance needed for a resistor in a series LED circuit can be calculated using Ohm's law. The formula is:

R = (Vs - (N × Vled)) / Iled


  1. R is the resistance required for the resistor.
  2. Vs is the supply voltage.
  3. N is the number of LEDs in series.
  4. Vled is the voltage drop across each LED.
  5. Iled is the current through the LED, typically in the range of 5-20 milliamperes.

Who wrote/refined the formula

Georg Simon Ohm is credited with the formulation of Ohm's Law in 1827, which forms the basis of this calculation. However, the formula's specific application in calculating the resistance required for a resistor in an LED circuit has been a product of the evolution of electronics technology.

Real Life Application

This calculation is routinely used in the design and creation of electronic devices that utilize LEDs, such as LED lighting systems, computer displays, televisions, traffic lights, and much more. It ensures the LEDs operate at the correct current level, which is critical for both efficiency and longevity.

Key individuals in the discipline

Georg Simon Ohm is a key figure in the field of physics, particularly in electricity and electronics. His formulation of Ohm's Law laid the foundation for vast developments in electrical circuits and electronics, which have transformed technology and society.

Interesting Facts

  1. The formula is essential in modern electronics manufacturing, with billions of LEDs produced and used in devices worldwide.
  2. Proper calculation of the resistor value in LED circuits has contributed to the remarkable energy efficiency of LED-based devices, resulting in significant energy savings globally.
  3. Ohm's law, the foundational principle behind this formula, is one of the fundamental laws in electrical engineering and physics.


Understanding the calculation of the resistance required for a resistor in an LED circuit is crucial in electronics, a key area in the field of physics. Mastery of these calculations helps to ensure the efficient and safe operation of an array of LED-based electronic devices, and contributes to the ongoing development and innovation in the field.

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