Voltage Reducer Resistor Calculator
Result
Required Resistor R1: Ohms
How to Use the Voltage Reducer Resistor Calculator
A Voltage Reducer Resistor Calculator is a tool that helps you determine the resistor value needed (R1) in a voltage divider circuit to step down a higher input voltage (Vin) to a desired output voltage (Vout) using a known resistor (R2).
What Is a Voltage Divider?
A voltage divider is a simple circuit using two resistors to reduce voltage. It follows the formula: Vout=Vin×R2R1+R2V_{out} = V_{in} \times \frac{R_2}{R_1 + R_2}Vout=Vin×R1+R2R2
Rearranging this formula allows us to calculate R1, the resistor you need to reduce voltage from a known Vin to Vout, using a known R2.
How to Use the Calculator
- Enter Input Voltage (Vin)
The voltage coming into your circuit (e.g., 12V from a battery). - Enter Desired Output Voltage (Vout)
The voltage you want after reduction (e.g., 5V to power an LED or microcontroller). - Enter Resistor R2 Value
This is the resistor you'll place between output and ground (e.g., 1000 ohms). - Click "Calculate R1"
The calculator computes the value of R1 (between Vin and Vout) in ohms.
Example
Suppose you want to drop 12V to 5V using a 1000 ohm resistor as R2.
The calculator will give you:
- Required R1: 1400 Ohms
This means you’ll need a 1.4kΩ resistor between 12V and 5V.
When to Use This
This calculator is ideal for:
- Electronics hobbyists designing custom circuits
- Students learning about voltage dividers
- Engineers creating non-precision voltage reductions
FAQ: Voltage Reducer Resistor Calculator
What does this calculator do?
It calculates the value of resistor R1 needed to reduce the voltage from Vin to Vout using a fixed R2 in a voltage divider circuit.
Can I input any resistor value for R2?
Yes, but results are most practical when using common resistor values (like 220Ω, 1kΩ, etc.).
What if I want a precise output voltage?
Voltage dividers are not ideal for precise or high-current loads. For stable voltage, use voltage regulators or buck converters.
What happens if I enter invalid values?
The calculator checks for:
- Vin must be greater than Vout
- R2 must be positive
- All inputs must be numbers
Can this be used for AC voltage?
No. This calculator is for DC low-voltage electronics, not for high-voltage or AC circuits.