DNA Melting Temperature Calculator (Tm)

Calculate the melting temperature (Tm) of DNA sequences using the Wallace rule or nearest-neighbor method.

Enter DNA sequence (A, T, G, C only)
Na⁺ concentration in mM
Oligonucleotide concentration
🧬 Tm Formulas:
Wallace Rule: Tm = 2°C × (A+T) + 4°C × (G+C)
Basic Formula: Tm = 64.9 + 41 × (G+C - 16.4) / Length
Nearest-Neighbor: Tm = (ΔH × 1000) / (ΔS + R × ln(C/4)) - 273.15
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Melting Temperature
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Step-by-Step Calculation

Detailed solution process

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Tm
°C
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Length
bp
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GC Content
%
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Method
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Sequence Composition

Base counts and composition

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Formula Reference

Tm calculation methods

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Tm Tips

Understanding DNA melting temperature

🧬 Biological Disclaimer: Tm calculations are estimates. Actual Tm can vary due to sequence context, buffer conditions, and instrument factors. For educational purposes.
DNA Tm Calculator  •  Nearest-Neighbor, Wallace Rule, Basic Formula  •  For educational purposes