Annealing Temperature Calculator

Calculate optimal PCR primer annealing temperature based on melting temperature (Tm) calculations.

Primer Sequences

Calculation Method

Forward Primer (5' to 3')

Reverse Primer (5' to 3')

Basic: Tm = 2(A+T) + 4(G+C)

Salt: Tm = 81.5 + 16.6×log[Na+] + 0.41(%GC) - 675/N

46.8°C

Range: 43.8°C - 49.8°C

Melting Temperature (Tm)54.4°C

Length21 bp

GC Content52.4%

CompositionA:5 T:5 G:6 C:5

Melting Temperature (Tm)51.8°C

Length20 bp

GC Content50.0%

CompositionA:5 T:5 G:5 C:5

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MyCalcBuddy Editorial Team

This page is maintained as an educational calculator reference.

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Formula Source: Standard Mathematical References

by Various

ðŸ”„Last reviewed: May 2026

âœ“Formula checks are based on standard references and internal QA review.