Torch Per Channel Quantization Calculator

Analyze channel compression with precise tensor controls. Switch modes and inspect dequantized outputs with confidence. Export clean summaries for optimization reviews and deployment planning.

Calculator

Use lines like: channel,min,max,sample

Example Data Table

Channel Min Max Sample Scale Zero Point Quantized Dequantized
filter_0 -1.2 1 0.73 0.00862745 11 96 0.73333333
filter_1 -0.8 0.9 -0.21 0.00666667 -8 -40 -0.21333333
filter_2 -1.5 1.7 1.11 0.01254902 -8 80 1.10431373
filter_3 -0.45 0.6 0.18 0.00411765 -19 25 0.18117647

Formula Used

Affine scale: scale = (max - min) / (qmax - qmin)

Affine zero point: zero_point = round(qmin - min / scale)

Symmetric scale: scale = max(|min|, |max|) / max(|qmin|, |qmax|)

Quantization: q = clamp(round(sample / scale) + zero_point, qmin, qmax)

Dequantization: dequantized = (q - zero_point) × scale

This calculator also reports clipping, absolute error, percentage error, and a simple SQNR estimate for every channel.

How to Use This Calculator

  1. Enter a tensor name and choose the channel axis.
  2. Select qint8 or quint8.
  3. Pick affine or symmetric per channel quantization.
  4. Choose whether you will paste min and max values or direct quantization parameters.
  5. Paste one channel per line in the format shown under the text area.
  6. Press the calculate button.
  7. Review scale, zero point, integer output, reconstruction error, and clipping status.
  8. Download the report as CSV or PDF when needed.

Torch Per Channel Quantization in AI Workflows

Why per channel quantization matters

Per channel quantization is widely used when one tensor range is not enough. A single global scale can hide channel level variation. That can increase reconstruction error. Per channel settings solve that by assigning independent scales and zero points. This often preserves more useful signal in convolution weights, projection layers, and other model parameters.

What this calculator measures

This calculator estimates per channel parameters from min and max calibration values or from direct manual inputs. It then maps the sample into the selected integer domain. After that, it dequantizes the value back to float space. You can review raw integer output, final clamped integer output, reconstructed float output, absolute error, percentage error, and SQNR. It is useful for quick audits and repeatable engineering reviews. That creates a practical inspection step before model export.

How practitioners use the results

ML engineers often compare affine and symmetric modes before freezing a model. They also compare qint8 and quint8 behavior. If one or more channels clip too often, calibration may be weak. The tensor distribution may also be drifting. Teams sometimes use this review to flag outlier channels, narrow observer settings, or revisit representative data. A better scale fit usually reduces clipping and improves dequantized fidelity. That matters for stable inference, repeatable benchmarking, and cleaner deployment validation.

Why scale and zero point matter

Scale tells you how much real value one integer step carries. Zero point tells you which stored integer represents real zero. Together they define the quantization grid. If the grid is too coarse, small detail disappears. If the grid is poorly centered, error grows faster. Careful parameter choice helps compressed tensors stay numerically useful.

Where this page helps most

Use this page during PyTorch quantization planning, tensor debugging, edge deployment review, and QA signoff. It works well for CNN filters, transformer projections, and custom research tensors. You can test channel behavior before committing to observer settings, calibration batches, or deployment thresholds. The CSV and PDF options also help teams archive results, compare experiments, and document why one scheme was selected over another. That makes the workflow easier to audit later.

FAQs

1. What is per channel quantization?

It assigns separate quantization parameters to each channel instead of using one shared scale for the full tensor. This often preserves weight detail better.

2. When should I use affine mode?

Use affine mode when ranges are not centered around zero. It can fit asymmetric distributions more tightly and reduce clipping.

3. When should I use symmetric mode?

Use symmetric mode when values are roughly balanced around zero and you want zero point fixed at zero. It is common for weight tensors.

4. What does clipping mean here?

Clipping means the raw quantized value exceeded the allowed integer range. The value was forced to qmin or qmax.

5. Why is reconstruction error important?

It shows how far the dequantized value moved from the original sample. Lower error usually means better numeric fidelity.

6. Why would reduce range help?

Reduce range narrows the integer interval by one bit. Some deployment flows use it for compatibility or stability checks.

7. Can I paste manual scale and zero point values?

Yes. Switch the input mode to manual parameters. Then paste channel, scale, zero point, and sample on each line.

8. What do CSV and PDF exports contain?

The exports include the main calculator summary and channel level results. They are useful for sharing quantization reviews and validation notes.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.