Series Resistance Calculator
Add ideal resistances connected in series.
Open toolLED Resistor Calculator
Calculate ideal LED-series limiting resistance and resistor power dissipation. Provide Supply voltage (V), Per-LED forward voltage (V), LEDs in series to compute results directly in your browser. Supply must exceed summed LED voltage. R=(Vs-N*Vf)/I and P=(Vs-N*Vf)*I; no standard-part rounding, tolerance, thermal design or circuit safety approval. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur.
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Enter the inputs, then select Calculate.
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How the LED Resistor Calculator Works & Core Formula
The LED Resistor Calculator evaluates Supply voltage (V), Per-LED forward voltage (V), LEDs in series in client-side JavaScript using the deterministic rule below and updates the output panel immediately without uploading data to a server.
Calculate ideal LED-series limiting resistance and resistor power dissipation.
Supply must exceed summed LED voltage. R=(Vs-N*Vf)/I and P=(Vs-N*Vf)*I; no standard-part rounding, tolerance, thermal design or circuit safety approval. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur.
LED Resistor Calculator Quick Reference & Input Guide
Review the input parameters, allowed value ranges, and worked reference cases for the LED Resistor Calculator below before running your calculation.
| Parameter / Scenario | Default / Sample Value | Rule or Allowed Range | Output / Usage Note |
|---|---|---|---|
| Input: Supply voltage (V) | 12 | Range: 1e-09 to 1000000000.0 | Required workspace parameter |
| Input: Per-LED forward voltage (V) | 2 | Range: 0 to 1000000000.0 | Required workspace parameter |
| Input: LEDs in series | 3 | Range: 1 to 1000 | Required workspace parameter |
| Input: Target current (mA) | 20 | Range: 1e-09 to 1000000000.0 | Required workspace parameter |
| Worked Case 1: Baseline run (Supply voltage (V) = 12) | Preloaded / test values | Calculate ideal LED-series limiting resistance and resistor power dissipation | Supply voltage (V) = 12; Per-LED forward voltage (V) = 2; LEDs in series = 3; Target current (mA) = 20. The displayed output is Resistance: 300 ohm Resistor power: 0.12 W Total LED voltage: 6 V. |
| Worked Case 2: Comparison scenario (led resistor calculator 12v) | Preloaded / test values | Calculate ideal LED-series limiting resistance and resistor power dissipation | Supply voltage (V) = 5; Per-LED forward voltage (V) = 2; LEDs in series = 1; Target current (mA) = 10. The displayed output is Resistance: 300 ohm Resistor power: 0.03 W Total LED voltage: 2 V. |
Step-by-Step Guide to Using the LED Resistor Calculator
Follow these three steps to configure Supply voltage (V), Per-LED forward voltage (V), LEDs in series, verify unit and boundary rules, and export your LED Resistor Calculator output.
Input and settings
Complete the other inputs
Set per-led forward voltage (v), leds in series, target current (ma). Supply must exceed summed LED voltage.
Tool result
Calculate and read the output
Select Calculate to see the ideal resistance, resistor power and total LED voltage. Copy result copies this text; Download saves it as a TXT file.
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Practical Worked Examples for LED Resistor Calculator
These concrete scenarios illustrate how the LED Resistor Calculator processes baseline inputs, comparison checks, and boundary constraints.
Baseline run (Supply voltage (V) = 12)
Supply voltage (V) = 12; Per-LED forward voltage (V) = 2; LEDs in series = 3; Target current (mA) = 20. The displayed output is Resistance: 300 ohm Resistor power: 0.12 W Total LED voltage: 6 V.
Comparison scenario (led resistor calculator 12v)
Supply voltage (V) = 5; Per-LED forward voltage (V) = 2; LEDs in series = 1; Target current (mA) = 10. The displayed output is Resistance: 300 ohm Resistor power: 0.03 W Total LED voltage: 2 V.
Boundary & unit check (Led Resistor Calculator)
When solving for 'led resistor calculator', verify that Supply voltage (V), Per-LED forward voltage (V), LEDs in series use consistent units and stay within the documented scope: Supply must exceed summed LED voltage. R=(Vs-N*Vf)/I and P=(Vs-N*Vf)*I; no standard-part rounding, tolerance, thermal design or circuit safety approval. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur.
How to Read and Verify the LED Resistor Calculator Output
The output panel reports the exact result derived from Supply voltage (V), Per-LED forward voltage (V), LEDs in series alongside any unit or formatting notes.
The result is the ideal resistance, resistor power and total LED voltage. Calculate a series-current resistor from supplied circuit quantities.
The calculated resistance is not rounded to a standard part, and thermal design remains outside the model.
Numerical output shows up to 12 significant digits. Floating-point arithmetic and display rounding can affect the last digits.
- Example input
- Supply voltage (V) = 12; Per-LED forward voltage (V) = 2; LEDs in series = 3; Target current (mA) = 20
- Example output
- Resistance: 300 ohm Resistor power: 0.12 W Total LED voltage: 6 V
Scope Limits, Accuracy Assumptions & Related Everyday Math Tools
Review these boundary constraints and validation rules before relying on the LED Resistor Calculator output.
Operational scope: Supply must exceed summed LED voltage. R=(Vs-N*Vf)/I and P=(Vs-N*Vf)*I; no standard-part rounding, tolerance, thermal design or circuit safety approval. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur. Inputs that violate minimum/maximum bounds or required format rules are rejected with a clear diagnostic prompt.
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Open toolFrequently Asked Questions About LED Resistor Calculator
Answers about using LED Resistor Calculator and understanding its results.
What formula or rule does the LED Resistor Calculator use?
The LED Resistor Calculator applies the rule: Calculate ideal LED-series limiting resistance and resistor power dissipation. Enter Supply voltage (V), Per-LED forward voltage (V), LEDs in series into the workspace and the tool computes the exact output in your browser.
What input parameters and units are required for LED Resistor Calculator?
Yes. Provide Supply voltage (V), Per-LED forward voltage (V), LEDs in series using the documented units and format shown in the quick reference table above. Preloaded default values let you test the workflow immediately.
What are the accuracy limits and boundary assumptions for LED Resistor Calculator?
Supply must exceed summed LED voltage. R=(Vs-N*Vf)/I and P=(Vs-N*Vf)*I; no standard-part rounding, tolerance, thermal design or circuit safety approval. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur. Confirm that your inputs fall within the allowed ranges before exporting the result.
Is the LED Resistor Calculator free and does it keep my inputs private?
Yes. All calculations for the LED Resistor Calculator execute 100% locally in your browser's JavaScript runtime. No inputs or results are uploaded to any external server.
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