qPCR Efficiency Calculator
Calculate amplification efficiency from a qPCR standard-curve slope, then interpret whether the assay is inside the practical 90-110% range.
Slope to qPCR efficiency
10-fold Ct spacing at 100% efficiency is 3.322 cycles.
Interpretation
Calculated result
qPCR efficiency from standard curve Slope: -3.35 Amplification factor: 1.988 Efficiency: 98.84% Intercept: 38.2 Expected Ct spacing for 10x dilution: 3.35 cycles Interpretation: 90-110% is commonly treated as an acceptable assay range. Also inspect R², residuals, melt curve or specificity data.
Worked example
If the standard curve slope is -3.35:
How to interpret the result
90-110% is commonly acceptable for qPCR standard curves.
Below 90% suggests poor amplification, inhibitors, primer issues, or dilution mistakes.
Above 110% is often a warning sign for contamination, non-specific signal, or non-linear curve points.
Why the standard curve quality matters
The slope is only as good as the dilution series behind it. Use at least five dilution points, keep the dilution factor consistent, and inspect whether low-template points are still linear before trusting the efficiency.
Related next steps
Need to prepare the dilution series after deciding copy number targets?
This page is scoped to slope-based qPCR efficiency and standard-curve interpretation. Plate layout planning now belongs to the dedicated Plate Map Generator so the calculator does not mix two different tasks.