ADC Resolution Calculator

Calculator Inputs

Choose a reference voltage or a custom input range, then compute step size, codes, and optional effective bits.

Tip: Use the unit selector for all voltage fields.

Resolution (bits)

Common values: 8, 10, 12, 16, 24.

Voltage unit

Applies to Vref, Vmin, Vmax, and Vin.

Oversampling ratio (optional)

Ideal averaging: +1 bit per 4× OSR.

Range selection

0 to Vref

Custom Vmin to Vmax

Vref

Used when range is 0 to Vref.

Vmin

Used only for custom range.

Vmax

Used only for custom range.

Input voltage Vin (optional)

If set, the calculator returns the nearest ADC code.

Target LSB (optional)

Compute required bits to meet the target step size.

Target unit

Used only for target LSB.

Reset

Formula Used

Codes = 2^N
FSR = V_max − V_min
LSB (ideal step size) = FSR / 2^N
% per LSB = (1 / 2^N) × 100
Quantization error ≈ ±0.5 × LSB
Effective bits (ideal averaging) = N + 0.5 × log₂(OSR)
Code ≈ round((V_in − V_min) / LSB), clamped to [0, 2^N−1]

These are ideal relationships. Real converters have offset, gain error, noise, and nonlinearity that reduce effective performance.

How to Use This Calculator

Select your resolution in bits.
Choose a voltage unit for all voltage inputs.
Pick 0 to Vref or enter a custom Vmin and Vmax.
Optionally enter an oversampling ratio to estimate ideal improvement.
Optionally enter Vin to get the nearest output code.
Optionally enter a target LSB to estimate required bits.
Press Submit to display results above the form.
Use Download CSV or Download PDF after a calculation.

Example Data Table

Bits	Range (V)	Codes	LSB (mV)	% per LSB
10	0 to 5.0	1024	4.8828	0.0977%
12	0 to 3.3	4096	0.8057	0.0244%
16	-2.5 to 2.5	65536	0.0763	0.0015%

Values are ideal and rounded for readability.

FAQs

1) What does “LSB” mean in an ADC?

LSB is the smallest ideal voltage change that moves the output by one code. It equals the input full-scale range divided by 2^N.

2) Is resolution the same as accuracy?

No. Resolution describes step size. Accuracy depends on offset, gain error, noise, and nonlinearity. A high-bit converter can still be inaccurate if errors dominate.

3) Why do some sources use 2^N − 1?

Some definitions use full-scale as the span between code 0 and the top code. This tool uses a common engineering approximation: step size = FSR / 2^N.

4) How do I choose Vmin and Vmax?

Set them to the expected minimum and maximum input after any conditioning. Leaving headroom helps avoid clipping when signals or offsets drift.

5) What is oversampling ratio (OSR) here?

OSR is how many samples you average per output sample. Ideal averaging improves noise performance. Practical improvement is often less due to correlated noise and limits in analog front-end bandwidth.

6) How is “effective bits” estimated?

This uses a simple rule: +0.5 bits per doubling of OSR, or +1 bit per 4×. It assumes white noise and effective averaging, not converter nonlinearity.

7) What happens if Vin is outside the range?

The computed code is clamped to the valid range, from 0 to 2^N−1. Real hardware typically saturates similarly at the rails.

8) Can this be used for differential or bipolar converters?

Yes. Use the custom range mode and enter your negative and positive endpoints. Then the tool computes FSR, step size, and codes for that span.