ADC Resolution Calculator
An analog-to-digital converter (ADC) maps a continuous input voltage onto a finite set of digital codes. The bit depth sets how finely it can divide the input: an N-bit converter has 2 to the power N levels. This calculator takes the bit depth and the full-scale reference voltage and returns the number of quantization levels, the voltage represented by one step (the LSB), and the resolution as a percentage of full scale. These figures define the smallest voltage change your converter can resolve.
ADC resolution formula
Levels = 2 ^ N
LSB (volts per step) = Vref / 2 ^ N
Resolution (% FS) = (1 / 2 ^ N) * 100
N is the bit depth and Vref is the full-scale input range. If your datasheet defines the top code as full scale, divide by (2 ^ N minus 1) instead. The LSB is the quantization step size: any input change smaller than one LSB cannot be distinguished.
Worked example
A 12-bit ADC with a 3.3 V reference: levels = 2 ^ 12 = 4,096. LSB = 3.3 / 4,096 = 0.000806 V = 0.81 mV. Resolution = (1 / 4,096) * 100 = 0.0244 percent of full scale. Each step represents about 0.81 mV at the input.
ADC resolution: frequently asked questions
What is ADC resolution?
ADC resolution is the smallest change in input voltage that an analog-to-digital converter can distinguish. An N-bit converter divides its full-scale reference range into 2 to the power N discrete levels, so the voltage per step (the LSB) equals the reference span divided by 2 to the power N.
What is one LSB?
One LSB (least significant bit) is the voltage represented by a change of one in the digital output code. It equals the full-scale voltage range divided by the number of steps. For a 0 to 5 V range and a 10-bit converter, one LSB is 5 / 1024, about 4.88 mV.
Why is the step count 2 to the power N rather than that minus one?
An N-bit converter produces 2 to the power N distinct output codes (0 to 2^N minus 1). Some texts divide the range by 2^N and some by 2^N minus 1, depending on whether the top code represents full scale or one step below it. This calculator reports both the level count (2^N) and the LSB using the conventional 2^N divisor; switch divisors in the formula section if your datasheet specifies otherwise.
Sources
- NIST Engineering Statistics Handbook: measurement and quantization principles.
- The quantization relations (levels = 2^N, LSB = Vref / 2^N) are standard digital signal definitions.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.