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LED Resistor Calculator

Science & Engineering

Nearest E24 value and power rating

Quick Answer

LED Resistor Calculator: Nearest E24 value and power rating. LED Resistor Calculator uses standard science & engineering formulas to compute accurate results instantly.

V
V
mA
LED color:
Use nearest E24 standard resistor
1.00 kΩ (1/16 W)
Exact value 150.0 Ω; actual current 3.0 mA

Calculation steps

  1. 1Kirchhoff: resistor drops the voltage the LED does not: V_R = Vs − Vf
  2. 2V_R = 5 − 2.0 = 3.0 V
  3. 3R = V_R / If = 3.0 / 20 mA = 150.0 Ω
  4. 4Nearest E24: 1000 Ω. Power: P = V·I = 9.0 mW → 1/16 W rating
Exact resistance150.0 Ω
E24 standard1000 Ω
Resistor power9.0 mW
LED power6.0 mW

LED forward voltage by color

ColorVf (typical)Note
Red2.0 VStandard
Orange2.1 VStandard
Yellow2.2 VStandard
Green2.2 VStandard
Blue3.2 VHigh — check headroom on 3.3 V supply
White3.2 VHigh — check headroom on 3.3 V supply
UV3.4 VHigh — check headroom on 3.3 V supply
IR1.4 VLow — can run 2 in series on 3.3 V
Never connect an LED without a current-limiting resistor — its near-zero internal resistance will draw destructive current instantly. Standard indicator LEDs run 10–20 mA; high-brightness ones up to 350 mA+ need constant-current drivers. For multiple LEDs in series, add their Vf values first.

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How to Use

  1. Enter known quantities: fill values and confirm units in the LED Resistor Calculator.
  2. Instant solution: unknowns solve live with the formula shown transparently.
  3. Use constant/material tables: standard physical constants and material data are listed on this page.
  4. Compare conditions: change inputs to compare scenarios.

Key Points

  • LED Resistor Calculator is a free online science & engineering tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Nearest E24 value and power rating.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

LED Resistor Calculator formula

LED Resistor Calculator uses standard science & engineering formulas to compute accurate results instantly.

FAQ

How do I use the LED Resistor Calculator?
Open the page and fill in the input fields — results update automatically. Nearest E24 value and power rating.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on CODATA recommended constants and standard physics formulas. Last updated: 2025-07

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. LED Resistor Calculator[EB/OL]. https://www.yijiansuan.com/en/c/science/led-resistor

Results provided by this tool are for reference only and do not constitute professional advice.