This section provides references for formulas used by Primer3 to calculate melting temperatures for the binding region of a primer. Under Formula you can choose between two diﬀerent tables of thermodynamic parameters and methods for melting temperature calculation:
Three diﬀerent Salt Correction Formula options are available:
The rough Tm of a selected region of sequence is dynamically calculated and displayed in the Statistics Tab in the Viewer side panel, and is calculated as per formulas 5.1 or 5.2 . The rough Tm is usually within 1-3° of that calculated by Primer3.
If you select a region of sequence less than 100 bp in length, then the Rough Tm will be displayed as a tooltip as shown in Figure 13.2 .