Voltage Divider Calculator for 5V to 3.3V Conversion
Common logic level conversion from 5V microcontroller output to 3.3V devices using a simple resistor divider.
Calculates the output voltage (Vout) of a two-resistor voltage divider circuit. Enter your Input Voltage (Vin), Resistor 1 (R1), Resistor 2 (R2) to get an instant output voltage (vout). Formula: vin * (r2 / (r1 + r2)).
Output Voltage (Vout)
Fill in the fields above and click Calculate
Comparison ()
| Field | |
|---|---|
| Result |
Formula
Step-by-step
Variables
Recent Calculations
How It Works
How It Works
A voltage divider uses two resistors connected in series to reduce an input voltage to a smaller output voltage. The output voltage is taken from the point between the two resistors.
This calculator applies the formula: Vin × (R2 / (R1 + R2)). It calculates how much of the input voltage appears across Resistor 2 based on the ratio of the two resistor values.
- Add R1 and R2 to get the total resistance
- Divide R2 by the total resistance (R1 + R2)
- Multiply that result by the input voltage (Vin)
- The result is the output voltage (Vout) in volts
Understanding the Results
The output voltage (Vout) tells you how much voltage is available at the point between the two resistors. It will always be less than or equal to the input voltage.
If R2 is larger than R1, the output voltage will be higher. If R2 is smaller than R1, the output voltage will be lower.
- Vout increases when R2 increases (relative to R1)
- Vout decreases when R1 increases (relative to R2)
- If R1 equals R2, Vout will be half of Vin
- The result is measured in volts (V)
Frequently Asked Questions
What does the Voltage Divider Calculator compute?
This calculator computes the output voltage (Vout) of a two-resistor voltage divider circuit. It uses the standard formula Vin × (R2 / (R1 + R2)) to determine how much of the input voltage appears across the second resistor. The result is provided in volts (V).
When should I use a voltage divider?
You should use a voltage divider when you need to reduce a higher voltage to a lower, specific value for a circuit component. Common applications include setting reference voltages, biasing transistors, and scaling signals for microcontroller inputs. It’s ideal for low-current signal applications.
How do I choose values for R1 and R2?
R1 and R2 determine the ratio of the output voltage relative to the input voltage. For example, if R1 and R2 are equal, the output voltage will be half of Vin. You can adjust the ratio R2 / (R1 + R2) to achieve your desired output voltage.
What units should I use for the inputs?
Enter the input voltage (Vin) in volts (V) and both resistor values (R1 and R2) in ohms (Ω). As long as both resistors use the same unit (e.g., ohms, kilo-ohms), the ratio remains correct. The output voltage will always be returned in volts.
Can this calculator be used for high-power circuits?
This calculator only computes the voltage ratio and does not account for power dissipation or current draw. In high-power applications, resistor wattage ratings and load effects must also be considered. Always verify that your resistors can safely handle the expected power.
What happens if I connect a load to the output?
When a load is connected to Vout, it effectively changes the resistance seen at R2, which can alter the output voltage. This calculator assumes no load (an ideal, open-circuit condition). For accurate results with a load, the load resistance must be included in the analysis.
Disclaimer
This calculator provides estimates for informational purposes only. It is not professional advice. Verify results with a qualified professional. Disclaimer.