LED Resistor Calculator

Find the correct resistor for any LED circuit.

Supply Voltage (V)

LED Forward Voltage (V)

LED Current (mA)

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Guides & Reference

How It Works

Find the correct resistor for any LED circuit. Enter your values and press Calculate for instant results with a full formula breakdown.

Formula

R = (Vs - Vf) / I

Common calculations — results you can verify instantly.

5V supply, 2V LED, 20mA

(5-2)/0.020

150Ω

12V supply, 3V LED, 20mA

(12-3)/0.020

450Ω

9V supply, 2V LED, 10mA

(9-2)/0.010

700Ω

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