Primer Melting Temperature Calculator

Estimate melting temperature (Tm) for PCR primers pasted one sequence per line. Optional name prefix: Fwd: ATGC...

Wallace rule (2(A+T)+4(G+C)) is shown for all primers. For primers ≥14 bp a salt-adjusted estimate is also shown (64.9 + 41(GC−16.4)/N with Na⁺ and concentration correction).

Limits

Approximate values for planning — not a replacement for nearest-neighbor tables or lab optimization. Up to {max} primers, {len} bp each.