Primer Tm Calculator

Estimate the melting temperature of a PCR primer from its sequence.

Primer sequence (5' → 3', bases A/T/G/C only)

These are quick-estimate formulas: the Wallace rule (for primers under 14 nt) and a basic salt-adjusted formula (14 nt and up). Both are estimates — they ignore mismatches, secondary structure, and actual salt/primer concentrations, which affect real annealing temperature.