Q Pcrefficiency Calculator
Free Pcrefficiency Calculator for genetics. Enter variables to compute results with formulas and detailed steps. Get results you can export or share.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Efficiency = (10^(-1/slope) - 1) x 100% ; Fold Change = 2^(-ddCt)
PCR efficiency is derived from the standard curve slope where a slope of -3.322 equals 100% efficiency. The delta-delta Ct method calculates relative gene expression: ddCt = (Ct_target - Ct_reference)_treated - (Ct_target - Ct_reference)_control. Fold change = 2^(-ddCt) assumes 100% efficiency.
Worked Examples
Example 1: Calculating PCR Efficiency from Standard Curve
Problem:A standard curve of 5 serial dilutions gives a slope of -3.45. What is the PCR efficiency?
Solution:Efficiency = (10^(-1/slope) - 1) x 100%\nE = (10^(-1/-3.45) - 1) x 100%\nE = (10^0.2899 - 1) x 100%\nE = (1.9488 - 1) x 100%\nE = 94.88%
Result:PCR efficiency = 94.88% (within acceptable range of 90-110%)
Example 2: Delta-Delta Ct Fold Change
Problem:Treated sample: target Ct=22.5, reference Ct=17.2. Control: target Ct=26.8, reference Ct=17.5. Calculate fold change.
Solution:deltaCt(treated) = 22.5 - 17.2 = 5.3\ndeltaCt(control) = 26.8 - 17.5 = 9.3\nddCt = 5.3 - 9.3 = -4.0\nFold change = 2^(-(-4.0)) = 2^4 = 16.0
Result:Fold change = 16x upregulation in treated vs control
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy