Reference Formula on Michael’s Domainhttps://jeltsch.org/en/tags/reference-formula/Recent content in Reference Formula on Michael’s DomainHugoen-usCopyright © 2002 - 2026 Michael Jeltsch.Fri, 24 Jul 2026 00:18:18 +0300Formula to Calculate the Annealing Temperature of Oligonucleotides for PCRhttps://jeltsch.org/en/annealing_temperature/Wed, 30 Aug 2006 00:00:00 +0000https://jeltsch.org/en/annealing_temperature/<p>The thumbrule for calculating the annealing temperature for a PCR primer isTm (°C) = 81.5 + 0.41(%GC) - (675/N) where %GC is the percentage of G and C nucleotides in the oligo and N is the length of the oligo given in nucleotides.</p>Molecular Weight and Extinction Coefficient of Oligonucleotideshttps://jeltsch.org/en/oligonucleotides/Wed, 30 Aug 2006 00:00:00 +0000https://jeltsch.org/en/oligonucleotides/<p>The formula to calculate the molecular weight of DNA oligonucleotides is:</p> <div class="codeblock syntax-highlight mb-3"><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-fallback" data-lang="fallback"><span class="line"><span class="cl">MW (g/mol) = (nA × 249,08619) + (nG × 265,0811) + (nC × 225,07496) + (nT × 240,07462)</span></span></code></pre></div></div><p>To calculate ε (epsilon, the extinction coefficient) of an oligo, the formula is:</p>