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LED resistor.

Find a current-limiting resistor for one DC-powered LED.

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01 / QUESTION

What ideal resistance fits a 5 V supply, 2 V LED and 10 mA?

R = (5 − 2) ÷ 0.01 = 300 Ω. Check the power rating too.

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How the calculation works

R = (supply voltage − LED forward voltage) ÷ current (A). Resistor power = drop across R × current.

KEY FORMULAR = (supply voltage − LED forward voltage) ÷ current (A). Resistor power = drop across R × current.
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Worked example

At 5 V, a 2 V LED and 15 mA, R = 200 Ω and the resistor dissipates about 0.045 W.

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Before you rely on this result

This is for one LED on a DC supply. Confirm rated LED current, actual voltage and thermal margin.

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Informational tool. It does not replace testing, measurement or professional advice when needed.

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Frequently asked questions

Can I use the exact resistor value?+

You normally choose the next equal or higher standard resistor to keep current lower.

Does this apply to LED strips?+

Many commercial strips include resistors or drivers; follow their specifications.