So, let’s take a look to see what the ∆∆Ct part of the equation means: So it is useful to use when summarising long formulas.
Delta is a mathematical term used to describe the difference between two numbers. Simply, it is the cycle number where the fluorescence generated by the PCR produce is distinguishable from the background noise.
This is given after the qPCR reaction by the qPCR machine. Let’s break the formula down into easier to understand chunks.įirstly, Ct stands for the cycle threshold (Ct) of your sample. This looks like a scary mathematical formula when in actual fact, it isn’t. The overall formula to calculate the relative fold gene expression level can be presented as: It is worthwhile understanding what the delta-delta Ct formula means before diving straight into the calculations. Understanding the delta-delta Ct method formula If you would like to download this, simply click here. Everything is done for you, all that is required is the Ct values! Use this to practise and get the hang of the calculations.
We have created a FREE Excel template which contains all of the formula described in this article below.
>Use code 20QPCR to get 20% off<< The FREE Microsoft Excel template Mastering qPCRįurther video tutorials on qPCR data analysis can be found in our Mastering qPCR course The method was devised by Kenneth Livak and Thomas Schmittgen in 2001 and has been cited over 61,000 times. The delta-delta Ct method, also known as the 2 – ∆∆Ct method, is a simple formula used in order to calculate the relative fold gene expression of samples when performing real-time polymerase chain reaction (also known as qPCR).