🧪 qPCR Efficiency Calculator
Estimate the amplification efficiency of your qPCR assay from two Ct values and the dilution factor used between them.
What qPCR efficiency measures
Quantitative PCR (qPCR) efficiency describes how well the target sequence doubles each amplification cycle. An ideal reaction doubles product every cycle, which corresponds to 100% efficiency. Most well-optimized assays fall in the 90-110% range.
The formula
This calculator uses the standard slope method: run the same template at two dilutions, note the Ct (cycle threshold) for each, and enter the fold-dilution between them. The slope of the implied standard curve is calculated as (Ct at higher dilution minus Ct at lower dilution) divided by log10(dilution factor). Efficiency is then E = (10^(-1/slope) – 1) x 100.
For best accuracy in a real lab workflow, use a full dilution series (at least 4-5 points) and linear regression rather than just two points. This tool is for general educational and lab-planning purposes.