# ADC Voltage Resolution Formula and Calculator

This tool computes the voltage resolution or the smallest voltage that can be measured by an analog-to-digital converter (ADC).

Every ADC specifies the number of bits it uses to digitize samples of the analog input. An n bit ADC produces 2n discrete digital levels.

The larger the number n, the higher the resolution.

Enter:

• Number of bits
• Minimum Analog Output Voltage

## ADC Resolution Formula

An ADC accepts an analog voltage at its input and converts it to an n-bit digital value. A 12-bit ADC for instance produces 212 = 4096 discrete values at its output.

The analog resolution or the smallest value that can be measured by the ADC is given by the formula:

(Vmax – Vmin)/2n

where

• Vmax is the maximum input voltage
• Vmin is the minimum input voltage
• n is the number of ADC bits

The difference between Vmax and Vmin is the input voltage range

## Calculation Example

A 12 bit ADC with an input voltage range of 3.3 Volt has a resolution of 0.81 mV.

Increasing the number of bits, increases the ADC resolution and therefore the precision of the measurement.

Note that an increase in resolution means the actual value of the voltage will decrease. A resolution value of 0.5 mV is greater than a resolution value of 0.8 mV for example.

## ADC Voltage Resolution Table

The following shows the ADC resolution for an input voltage range of 5V