What is qPCR efficiency?
Quantitative PCR (qPCR) efficiency describes how well the polymerase chain reaction amplifies the target DNA in each cycle. An efficiency of 100% means the amount of DNA exactly doubles with every thermal cycle. In practice, efficiencies between 90% and 110% are considered acceptable for reliable quantification.
qPCR efficiency formula
The efficiency is calculated from the slope of a standard curve (Cq vs. log₁₀ of template amount):
E = 10(-1/slope) − 1
A perfect efficiency of 100% corresponds to a slope of −3.322. Slopes steeper than this indicate lower efficiency, while shallower slopes signify higher efficiency.
Interpreting your results
- 90–110% efficiency: Acceptable range for publication-quality data.
- <90% efficiency: May indicate primer dimers, suboptimal annealing temperature, or template secondary structure.
- >110% efficiency: Could indicate pipetting errors or inhibitors in the reaction.
How to use this calculator
Simply enter the slope from your standard curve (typically a negative number like −3.3) and the calculator will instantly compute the reaction efficiency.