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LED Series Resistor Sizing Calculator

Online led series resistor sizing calculator. Single ideal LED with supplied forward voltage; choose component tolerances separately.

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led series resistor sizing calculator online

Use led series resistor sizing calculator online for supply V, forward V, current A. Single ideal LED with supplied forward voltage; choose component tolerances separately. Ideal nominal component model. Verify topology, operating range, tolerances and ratings against the actual component datasheet.

How to use it

Enter supply V. Set forward V, current A. Select Calculate and check the labeled output. Copy or download the JSON result.

Options and example settings

OptionChoices / valueExample default
supply VMain input. Positive values. 5
forward VOption. Positive values. 2
current AOption. Positive values. 0.02

Calculation method

resistance_ohm = positive(supply_V-forward_V)/current_A; resistor_W = (supply_V-forward_V)*current_A (^ means exponentiation; trig functions ending in d use degrees).

Worked examples

Apply led series resistor sizing calculator to the case below, keeping the displayed units and assumptions. Single ideal LED with supplied forward voltage; choose component tolerances separately.

LED Series Resistor Sizing Calculator — worked case

Settings: forward V: 2; current A: 0.02

Input:

5

Calculated result for these inputs:

Output:

{
  "resistance_ohm": 150,
  "resistor_W": 0.06
}

Choose the right tool

Match the topology before entering values: series and parallel networks, inverting and noninverting stages, and buck and boost converters use different equations. Component ratings, parasitics, protection and measured conditions require separate review.

Limitations and common mistakes

  • Single ideal LED with supplied forward voltage; choose component tolerances separately. Ideal nominal component model. Verify topology, operating range, tolerances and ratings against the actual component datasheet.
  • Use the displayed unit in every field. Ratios and percentages are different inputs; percent fields use values such as 25 rather than 0.25.

Frequently asked questions

How can I use led series resistor sizing calculator online?

Enter supply V. Set forward V, current A. Select Calculate and check the labeled output. Copy or download the JSON result.

Technical references

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.

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