Voltage Divider Calculator

Voltage Divider is evaluated from Input Voltage, Resistor R1 and Resistor R2. The calculation reports Output Voltage, Voltage Ratio and R2 for target Vout.

Results

Thanks — we’ve logged this for review.

About the Voltage Divider Calculator

### Why Use the Voltage Divider Calculator Calculator?
The Voltage Divider Calculator is a valuable tool for anyone working with electronic circuits, particularly when designing or troubleshooting voltage divider networks. A voltage divider is a simple circuit that reduces a high input voltage to a lower output voltage, which is essential in various applications, such as scaling down sensor outputs to match the input requirements of microcontrollers or creating bias voltage networks. This calculator helps users determine the output voltage, voltage ratio, and the required value of the second resistor (R2) for a target output voltage. By using this calculator, users can quickly and accurately design voltage dividers, saving time and reducing the risk of errors.

### History of the Voltage Divider Calculator
The concept of voltage division dates back to the early days of electrical engineering. The voltage divider rule, which states that the voltage across a resistor in a series circuit is proportional to the resistance of that resistor, was first described by German physicist Georg Ohm in 1827. Ohm's law, as it came to be known, is the foundation of the voltage divider calculator. Over the years, the voltage divider has become a fundamental component in electronic circuits, and its calculation has been standardized. The development of electronic calculators and computers has made it possible to create software tools, such as the Voltage Divider Calculator, that can perform these calculations quickly and accurately.

### The Science Behind the Calculations
The Voltage Divider Calculator is based on the voltage divider formula: Vout = (R2 / (R1 + R2)) * Vin, where Vout is the output voltage, R2 is the resistance of the second resistor, R1 is the resistance of the first resistor, and Vin is the input voltage. This formula is derived from Ohm's law and the principle of series circuits. The calculator also uses the formula for the voltage ratio: Voltage Ratio = R2 / (R1 + R2). To find R2 for a target output voltage, the calculator rearranges the voltage divider formula to solve for R2: R2 = (Vout / Vin) * (R1 / (1 - (Vout / Vin))). The calculator also calculates the divider current (I) using the formula: I = Vin / (R1 + R2).

### Real-Life Application and Examples
Suppose we want to scale down the output of a 5V sensor to 3.3V, which is the input requirement of our microcontroller. We can use the Voltage Divider Calculator to determine the required values of R1 and R2. Let's assume we have a 10kΩ resistor (R1) and we want to find the value of R2. We enter the input voltage (Vin) as 5V, R1 as 10kΩ, and the target output voltage (Vout) as 3.3V. The calculator returns the output voltage (Vout) as 3.3V, the voltage ratio as 0.66, and R2 as 6.67kΩ. This means that we need a 6.67kΩ resistor (R2) in series with the 10kΩ resistor (R1) to achieve an output voltage of 3.3V. The calculator also returns the divider current (I) as 0.23mA. With this information, we can design a voltage divider network that meets our requirements and ensures reliable operation of our microcontroller.

Formula & How It Works

The calculation applies the following relations exactly as recorded in the metadata:

Vout = Vin x R2 / (R1 + R2)
R2 = Vout x R1 / (Vin - Vout)
I = Vin / (R1 + R2) (in amperes)

Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.

Worked Examples

Example 1: 5V to 3.3V Level Shift — Arduino to ESP32

Inputs

vin: 5 r1: 10000 r2: 20000
Output Voltage: 3.3333 V. Voltage Ratio: 0.6667. Divider Current: 0.1667 mA

With Input Voltage = 5, Resistor R1 = 10,000 and Resistor R2 = 20,000 as the stated inputs, the result is Output Voltage = 3.3333 V, Voltage Ratio = 0.6667 and Divider Current = 0.1667 mA. Each value corresponds to the declared output fields.

Example 2: Find R2 for 2.5V Reference

Inputs

vin: 5 r1: 10000 vout: 2.5
R2 for target Vout: 10,000 Ω

With Input Voltage = 5, Resistor R1 = 10,000 and Target Vout = 2.5 as the stated inputs, the result is R2 for target Vout = 10,000 Ω. Each value corresponds to the declared output fields.

Example 3: 12V Car Battery Monitor → 5V ADC

Inputs

vin: 12 r1: 33000 r2: 22000
Output Voltage: 4.8 V. Voltage Ratio: 0.4. Divider Current: 0.2182 mA

With Input Voltage = 12, Resistor R1 = 33,000 and Resistor R2 = 22,000 as the stated inputs, the result is Output Voltage = 4.8 V, Voltage Ratio = 0.4 and Divider Current = 0.2182 mA. Each value corresponds to the declared output fields.

Example 4: NTC Thermistor Temperature Sensor

Inputs

vin: 3.3 r1: 10000 r2: 10000
Output Voltage: 1.65 V. Voltage Ratio: 0.5. Divider Current: 0.165 mA

With Input Voltage = 3.3, Resistor R1 = 10,000 and Resistor R2 = 10,000 as the stated inputs, the result is Output Voltage = 1.65 V, Voltage Ratio = 0.5 and Divider Current = 0.165 mA. Each value corresponds to the declared output fields.

Common Use Cases

  • Scale 5V sensor output down to 3.3V for a microcontroller
  • Design a bias voltage network
  • Find R2 for a target output voltage