LibraTool logoLibraTool
⚡
💡

Size a Current-Limiting Resistor for an LED

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

Реєстрація не потрібна
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.

Як це працює

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

Чому наш?

✓Повністю безкоштовно — ніяких прихованих витрат, ніколи
✓Не потрібен акаунт, пошта або реєстрація
✓Файли ніколи не залишають ваш пристрій
✓Жодних обмежень по розміру файлів
✓Без водяних знаків на будь-яких результатах

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

Часті запитання

Back to Ohm's Law Calculator