What is the SNR formula for ADC bit depth?

For a full-scale sinusoidal input with an ideal N-bit uniform quantizer, the theoretical SNR is SNR = 6.02 × N + 1.76 dB. Each additional bit adds approximately 6 dB of SNR.

Where does the 1.76 dB come from?

The 1.76 dB offset comes from the power ratio of a full-scale sinusoid to the uniform quantization noise. Specifically, it is 10 × log10(3/2) ≈ 1.76 dB, derived from the sinusoid crest factor and the ÷12 noise model.

What is dynamic range and how does it differ from SNR?

Dynamic range is the ratio of the largest undistorted signal to the noise floor, expressed in dB: DR = 20 × log10(2^N) = 6.02 × N dB. It excludes the sinusoid-specific 1.76 dB term, so it is slightly lower than theoretical SNR.

ENOB (effective number of bits) converts a measured SNR back to an equivalent bit depth: ENOB = (SNR_dB − 1.76) / 6.02. Real converters always have ENOB below their nominal bit depth due to thermal noise, distortion, and jitter.

Does this formula apply to any waveform?

No. The +1.76 dB term is specific to a full-scale sinusoidal (single-tone) input. For a square wave the formula becomes 6.02N + 3.01 dB; for a sawtooth it is 6.02N + 0.79 dB. This tool uses the sinusoid case, which is the most common audio and RF benchmark.

Why does each bit add ~6 dB of SNR?

Doubling the number of quantization levels (adding one bit) halves the LSB step size, which reduces quantization noise power by a factor of 4 (−6 dB). Signal power stays the same, so SNR increases by 6 dB per bit.

SNR from Bit Depth Calculator

Name: SNR from Bit Depth Calculator
Availability: InStock
Author: Nham Vu

Enter an ADC bit depth to instantly get theoretical SNR in dB, dynamic range, and ENOB — with a reference table for common resolutions.

Parameters

Bit Depth (N)

bits

Resolution of the ADC/DAC (1–32 bits).

Measured SNR (optional)

Enter a real measured SNR to compute ENOB and compare against the theoretical limit.

Formula (full-scale sinusoid)

SNR = 6.02 × N + 1.76 dB

+6 dB per additional bit; 1.76 dB from sinusoid crest factor.

Results

Theoretical SNR

6.02 × N + 1.76 dB

—

Dynamic Range

20 × log₁₀(2^N)

—

Quantization Levels

2^N

—

ENOB (theoretical)

(SNR − 1.76) / 6.02

—

bits

Common ADC Resolutions — Theoretical SNR Reference

Bit Depth	Levels (2^N)	Theoretical SNR	Dynamic Range	Typical Application
4 bit	16	25.8 dB	24.1 dB	Simple control systems
8 bit	256	49.9 dB	48.2 dB	Legacy PC audio, telephony
10 bit	1,024	62.0 dB	60.2 dB	MCU ADCs, basic sensors
12 bit	4,096	74.0 dB	72.2 dB	Industrial sensors, oscilloscopes
14 bit	16,384	86.0 dB	84.3 dB	RF receivers, radar
16 bit	65,536	98.1 dB	96.3 dB	CD audio, pro audio
20 bit	1,048,576	122.2 dB	120.4 dB	High-res audio, precision instruments
24 bit	16,777,216	146.2 dB	144.5 dB	Studio recording, medical imaging
32 bit	4,294,967,296	194.2 dB	192.5 dB	Scientific data acquisition

Summary