Primer Melting Temperature Calculator

Enter a primer sequence and this tool returns its melting temperature by nearest-neighbour thermodynamics, using SantaLucia's 1998 unified parameters with the salt and oligo concentration you set. It prints the enthalpy, the entropy and the free energy at 37 C, the per-pair table those come from, and the same Tm as the 2 + 4 Wallace rule and the salt-adjusted GC formula would give it. Those two shortcuts ignore the order of the bases entirely, which is how GCGCGCGC and GGGGCCCC both come out at 32 C by the Wallace rule while the real gap between them is over ten degrees. Magnesium and dNTPs are not modelled, so a real PCR buffer reads a few degrees above the figure shown.