📈 qPCR Efficiency Calculator
Evaluate qPCR assay performance using the slope of your standard curve.
Ideal slope is -3.32, corresponding to 100% efficiency.
Intercept is recorded for reference but not used in efficiency.
How to Use This Calculator
Generate a standard curve
Prepare serial dilutions of your template and record Ct/Cq values to build a log concentration vs. Ct plot.
Obtain the slope
Run linear regression on the standard curve to determine the slope (usually between -3.1 and -3.6).
Calculate efficiency
Enter the slope here to instantly compute amplification efficiency and assess assay quality.
Formula
Efficiency (%) = (10(-1/slope) − 1) × 100
A slope of -3.32 corresponds to perfect doubling (100% efficiency). Deviations indicate pipetting errors, reaction inhibition, or suboptimal primer design.
Frequently Asked Questions
Why is the ideal slope -3.32?
A slope of -3.32 indicates that DNA doubles each cycle (amplification factor of 2). This corresponds to 100% efficiency, a benchmark for well-optimized qPCR assays.
What causes efficiency above 110%?
Efficiencies over 110% often result from inaccurate standards, primer-dimer formation, or fluorescence artifacts. Verify dilution accuracy and melt curve profiles.
Can I enter positive slopes?
Standard curves should yield negative slopes (Ct decreases with higher template amounts). Positive slopes indicate an error in data entry or analysis.
Does intercept affect efficiency?
No. Efficiency depends solely on the slope. The intercept reflects baseline Ct values but does not influence amplification kinetics.