ADC Resolution Calculator (LSB, SNR, Output Code)
Enter the number of bits, the reference voltage and an input voltage.
Your numbers
Your results
Number of levels
Number of levels
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Step size, 1 LSB (mV)
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Ideal SNR (dB)
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Output code for the input
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Code in hexadecimal
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ADC Resolution Calculator (LSB, SNR, Output Code) by TheCalcTools
How the ADC Resolution Calculator (LSB, SNR, Output Code) works
An n-bit ADC divides the reference voltage into 2ⁿ steps; one step (the least significant bit) is Vref ÷ 2ⁿ. The output code is the input divided by the step, rounded down and capped at full scale.
An ideal converter’s quantisation noise limits its SNR to 6.02n + 1.76 dB for a full-scale sine wave. Real ADCs reach fewer effective bits (ENOB).
The formula
LSB = Vref ÷ 2ⁿ; SNR = 6.02n + 1.76 dB
Worked example
Using the default values shown in the calculator:
| Resolution (bits) | 12 |
|---|---|
| Reference voltage (V) | 3.3 |
| Input voltage (V) | 1.65 |
- 12 bits at 3.3 V: 4,096 levels of 0.8057 mV.
- 1.65 V reads as code 2,048 (0x800).
Result:
| Number of levels | 4,096 |
|---|---|
| Step size, 1 LSB (mV) | 0.8057 |
| Ideal SNR (dB) | 74.00 |
| Output code for the input | 2,048 |
| Code in hexadecimal | 800 |
Frequently asked questions
What is the resolution of a 12-bit ADC at 3.3 V?
About 0.806 mV per step.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.