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ADC Voltage Calculator

Calculate analog input voltage from ADC counts, resolution and reference voltage.

Analog Signal to Digital Value
Analog Input
Voltage
→
ADC
→
ADC Count
STEP 1

What do you want to calculate?

Input Voltage Calculate voltage from ADC count
ADC Count Calculate ADC digital value from voltage
ADC Resolution Calculate voltage per ADC step
Reference Voltage Calculate required ADC reference voltage
STEP 2

Enter the values you know

counts
Digital value returned by the ADC.
Select the number of ADC bits.
V
ADC reference voltage, such as 3.3 V or 5 V.
V
Result

What is an ADC?

An ADC, or Analog to Digital Converter, converts an analog voltage into a digital number that a microcontroller can process.

ADC Voltage Formula

Voltage = ADC Count × Vref ÷ (2ⁿ - 1)

n is the ADC resolution in bits. Vref is the ADC reference voltage.

ADC Count Formula

ADC Count = Voltage × (2ⁿ - 1) ÷ Vref

ADC Resolution

Voltage per Step = Vref ÷ (2ⁿ - 1)

Example

Consider a 12-bit ADC with a 3.3 V reference. If the ADC returns a count of 2048:

Voltage = 2048 × 3.3 ÷ 4095

The measured voltage is approximately 1.6504 V.

Common ADC Resolutions

  • 8-bit ADC: 256 levels
  • 10-bit ADC: 1024 levels
  • 12-bit ADC: 4096 levels
  • 14-bit ADC: 16384 levels
  • 16-bit ADC: 65536 levels

ADC in Embedded Systems

Microcontrollers such as STM32, ESP32, AVR and PIC commonly include ADC peripherals for measuring sensors, batteries, potentiometers and other analog signals.

The actual ADC behavior can depend on the MCU, reference source, input range, calibration and ADC configuration.