ADC Step Size Formula and Calculator

The step size of an ADC (Analog-to-Digital Converter) is the smallest change in input voltage that can be resolved by the ADC.


  • Reference Voltage Vref
  • Number of bits (n)

The tool will provide the step size in Volt, Millivolt, Microvolt or Nanovolt.


The step size of the ADC is given by the formula:


Example Calculation

For a 12-bit ADC and a reference voltage equal to 3.3 V, the step size is 1.6 mV.

As the number of bits increases, the step size decreases thereby increasing the granularity in voltage values that can be detected and measured by the ADC.

What is ADC Reference Voltage?

The reference voltage sets the maximum input voltage the ADC can convert and determines the resolution of the digital output.

Types of Reference Voltages

  1. Internal Reference: Some ADCs have an internal reference voltage that is generated within the ADC itself. This is convenient and ensures that the reference voltage is stable and accurate.
  2. External Reference: In other cases, an external reference voltage can be supplied to the ADC. This allows for flexibility in choosing the reference voltage and can be beneficial for applications requiring a very precise and stable reference.

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The Scientist & Engineer's Guide to Digital Signal Processing