Delta-Delta CT/Comparative CT Method Of Calculating Real-Time PCR Data Using Excel

For those who prefer to calculate their real-time PCR or qPCR data using the DDCT (also referred to as comparative CT) method but want to be able to evaluate the calculation of the data step by step, the following set of Excel formulae will come in handy. The Columns referred to correspond to the columns in the figure below.

Cell Formulae

Column B: Gene 1 CT values from your qPCR run

Column C: Gene 2 CT values from your qPCR run

Column D: Housekeeping gene CT values from your qPCR run

Column E: =B4-D4, =B5-D5, etc

Column F: =C4-D4, =C5-D5, etc

Column G: =AVERAGE(E4:E6)

Column H: =AVERAGE(F4:F6)

Column I: =E4-$G$4, =E5-$G$4, etc

Column J: =F4-$H$4, =F5-$H$4, etc

Column K: =POWER(2,-I4),=POWER(2,-I5), etc

Column L: =POWER(2,-J4), =POWER(2,-J5), etc

Column M: =AVERAGE(K4:K6), =AVERAGE(K7:K9), etc

Column N: =AVERAGE(L4:L6), =AVERAGE(L7:L9), etc

Column O: =STDEV(K4:K6), =STDEV(K7:K9),etc

Column P: =STDEV(L4:L6), =STDEV(L7:L9), etc

Column Q: =O4/SQRT(3), =O7/SQRT(3), etc

Column R: =P4/SQRT(3), =P7/SQRT(3), etc