LibraTool logoLibraTool
⚡
💡

Size a Current-Limiting Resistor for an LED

Work out the resistor value an LED needs from supply voltage and current.

Ingen pålogging kreves
V
A
Ω
W
Enter any two values and the other two are solved automatically

💡 Ohm's law: V = I × R. Power adds P = V × I. Knowing any two lets you derive the rest — handy for sizing resistors, checking LED current, or working out heat dissipation.

LEDs tips

💡

Resistor value R = (supply V − LED forward V) ÷ LED current. Enter the voltage drop and target current to get R.

🎯

A typical LED wants ~20mA (0.02A). With a 5V supply and a 2V LED, that needs ~150Ω.

⚡

Check the power too — the calculator shows watts so you can pick a resistor that won't overheat.

Hvordan det fungerer

1
Gå inn
Enter your data into the tool above. Everything stays local to your browser.
2
Prosess
The tool processes your data instantly in your browser using JavaScript. No server, no waiting.
3
Last ned
Get your result instantly. Nothing is stored after you leave the page — complete privacy.

Hvorfor bruke vår?

✓Helt gratis – aldri noen skjulte kostnader
✓Ingen konto, e-post eller pålogging kreves
✓Filer forlater aldri enheten din
✓Ingen filstørrelsesbegrensninger overhodet
✓Ingen vannmerker på noen utgang

Also check out…

🔥

Calculate Power Dissipation (Watts)

Find how many watts a component dissipates so you

🎓

Solve Ohm's Law Homework

Check circuit problems by entering any two known v

🔋

Estimate Current Draw from a Battery

Find the current a load pulls so you can estimate

📉

Calculate Voltage Across a Component

Find the voltage drop across a resistor from curre

Ofte stilte spørsmål

Back to Ohm's Law Calculator