How does the L E D Resistor Calculator work?

Supply voltage (V) Then: LED forward voltage (typically 1.5-3.5V) Then: Desired LED current (typically 2-20mA) Then: Formula: R = (V - Vf) ÷ I.

Can you give an example of how to use the L E D Resistor Calculator?

Example: Input LED 2V, supply 5V, 20mA gives a result of 150ohm resistor.

Is the L E D Resistor Calculator free to use?

Yes — completely free with no registration, download, or subscription required. All calculations happen instantly in your browser.

How accurate is the L E D Resistor Calculator?

Our L E D Resistor Calculator uses verified mathematical formulas and is accurate to multiple decimal places. Results are calculated in real-time using the same methods used by professionals.

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L E D Resistor Calculator

LED Resistor Calculator

Supply Voltage (V)

LED Forward Voltage (V)

LED Current (mA)

Calculates resistor value needed to limit current through an LED to safe operating levels. Prevents LED burnout and extends lifespan.

Symbol	Name	Unit	Description
R	(V - Vf) ÷ I	—	(V - Vf) ÷ I
V	V value	—	Variable used in the calculation
Vf	Vf value	—	Variable used in the calculation
I	I value	—	Variable used in the calculation

Difficulty:beginner

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Did You Know?

One incorrectly sized LED resistor can fail and damage expensive electronic circuits.

References

›LED Resistor Calculator

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L E D Resistor Calculator

LED Resistor Calculator

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