Enter your DNA Sequence, choose your Strand Type and whether a 5' Phosphate Group is present, then plug in your Salt Concentration and DNA Concentration to calculate key sequence properties — including GC Content, Molecular Weight, Melting Temperature (Tm), Extinction Coefficient, and total Sequence Length.
Sequence Length
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GC Content
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Molecular Weight
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Melting Temperature (Tm)
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Extinction Coefficient
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Mass per Picomole
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GC content is the percentage of guanine (G) and cytosine (C) nucleotides in a DNA sequence. It affects DNA stability, melting temperature, and PCR efficiency. Higher GC content generally means higher melting temperature.
Tm is calculated using the nearest-neighbor method considering base-pair stacking energies, salt concentration, and DNA concentration. The formula accounts for thermodynamic parameters of each dinucleotide step.
Double-stranded DNA has approximately twice the molecular weight of single-stranded DNA of the same sequence, plus the weight of complementary bases. The calculator adjusts the molecular weight based on your strand type selection.
Higher salt concentrations increase the melting temperature by stabilizing the DNA double helix. Monovalent salts like NaCl shield the negative charges on the DNA backbone, making denaturation require higher temperatures.
The extinction coefficient allows you to calculate DNA concentration from UV absorbance measurements at 260nm. It represents how strongly the DNA absorbs UV light per molar concentration.
Phosphate groups add significant mass to the DNA molecule. Triphosphate groups (as in cellular DNA) are heavier than monophosphate groups (common in synthetic oligos), affecting the total molecular weight calculation.
This calculator is specifically designed for DNA sequences (A, T, G, C). For RNA analysis, you would need a calculator that accounts for uracil (U) instead of thymine (T) and different thermodynamic parameters.