Oligo Calculator (%GC, Tm, MW, etc.)

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[Original Javascript program by Eugen Buehler,
University of Pittsburgh School of Medicine]

The common Tm formulas for calculating the theoretical Tm of an oligo are:

The simlest formula:

T_m= 4°C x (number of G’s and C’s in the primer) + 2°C x (number of A’s and T’s in the primer)

Salt-Adjusted T_m Calculation Formula:

T_m= 81.5 + 16.6 x (log₁₀{[Na⁺] + [K⁺]}) + 0.41 x (%G+C) – 675/n

Where: n is the number of nucleotides of the oligo
[Na⁺] and [K⁺] are the final concentrations of the sodium and potassium ions in the reaction, respectively

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