Enter the number of A, T, G, and C nucleotides into the calculator to determine the melting temperature (Tm).

Idt Primer Formula

The following formula is used to calculate the Idt Primer Tm.

Tm = (64.9 + 41 * (G + C - 16.4) / (A + T + G + C))


  • Tm is the melting temperature (°C) A, T, G, C are the number of each respective nucleotide in the primer sequence

To calculate the melting temperature of the primer, add 64.9 to the result of 41 times the sum of the number of G and C nucleotides, minus 16.4, all divided by the total number of all nucleotides (A, T, G, C) in the primer sequence.

What is a Idt Primer?

An IDT primer is a short, single-stranded DNA sequence that is used in molecular biology procedures such as polymerase chain reaction (PCR) and DNA sequencing. IDT, or Integrated DNA Technologies, is a company that specializes in the production of these custom-made primers. These primers are designed to bind to a specific DNA sequence in a sample, allowing for the amplification or sequencing of that specific DNA region.