Voltage Divider Calculator – Online Tool for Arduino & Electronics

Voltage Divider Calculator

Input Voltage (V)


Resistor 1 (Ω)


Resistor 2 (Ω)


Calculate

Output Voltage (V): –

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What is a Voltage Divider?

A voltage divider is a simple circuit that turns a large voltage into a smaller one using two resistors. It is often used to reduce voltage levels for analog sensors to make them safe for microcontroller inputs (like on Arduino).

Example

Suppose you have a 5V input and want to use 10kΩ and 20kΩ resistors. The output voltage would be:
Vout = 5 × (20 / (10 + 20)) = 3.33V

FAQs

How do I choose resistor values?

Choose values based on your desired output voltage and input voltage. Common values are 10kΩ and 20kΩ, 1kΩ and 2kΩ, etc. Try to keep the total resistance above 1kΩ to limit power loss.

Does resistor tolerance matter?

Yes. If you need high accuracy, use resistors with 1% or better tolerance. For general use, 5% tolerance is acceptable.

Is this calculator accurate for all voltages?

This calculator assumes ideal conditions. Real circuits might have small deviations due to resistor tolerance, wire resistance, or load effects.