Z-Factor Calculator

Calculate Z-factor (Z') for assay quality control in high-throughput screening and plate-based assays

What is Z-Factor Calculator?

The Z-factor (Z') is a statistical parameter used to evaluate the quality of high-throughput screening assays. It measures the separation between positive and negative controls, indicating how reliable an assay is for detecting true hits while minimizing false positives and negatives.

How to Use This Z-Factor Calculator

Quick guide to calculate Z-factor:

  1. Enter positive control values (comma or space separated)
  2. Enter negative control values (comma or space separated)
  3. View Z-factor calculation and quality assessment
  4. Download or copy the detailed analysis

When to Use

This Z-factor calculator is essential for:

  • High-throughput screening (HTS) assay validation
  • Plate-based assay quality control
  • Drug discovery screening optimization
  • Biochemical and cell-based assay development
  • Laboratory automation quality assessment

Example Input

Positive controls (high signal):

95.2, 97.1, 94.8, 96.5, 95.9, 96.8, 94.3, 97.5

Negative controls (low signal):

12.3, 11.8, 13.1, 12.0, 11.5, 12.8, 11.2, 13.5

Z-Factor Interpretation

Quality assessment ranges:

Z' > 0.5: Excellent assay 0 < Z' ≤ 0.5: Good assay -0.5 < Z' ≤ 0: Marginal assay Z' ≤ -0.5: Poor assay

Higher Z-factor values indicate better assay quality and reliability.

FAQ

Q: What does Z-factor measure?
A: Z-factor measures the separation between positive and negative controls relative to their variability, indicating assay quality.

Q: What's the minimum number of controls needed?
A: At least 3 replicates per control type, but 8-16 replicates are recommended for accurate statistics.

Q: Can Z-factor be negative?
A: Yes, negative Z-factors indicate poor assay quality with overlapping control populations.