Primer Tm for PCR planning
Primer melting temperature helps estimate an appropriate annealing temperature range for PCR.
This calculator provides a simple Wallace-rule estimate and a basic longer-primer estimate when appropriate.
Calculator
Primer Tm Calculator
Result
Wallace-rule Tm: 48 °C
Basic longer-primer estimate: 43.4 °C
Length: 16 bases
Base counts: A 4, T 4, G 5, C 3
GC content: 50%
Practical use
Use this calculator as a planning aid for molecular biology, biochemistry, protein science, cloning, PCR, and routine bench preparation workflows.
Results should be interpreted alongside your protocol, instrument settings, reagent quality, and laboratory safety requirements.
How to cite this tool
Citation
If this calculator supports your research, you may cite it as a web-based tool.
Abdulfattah, M. A. Primer Tm Calculator. Mustafa A Abdulfattah Academic Website. Available at: https://www.mustafaabdulfattah.com/tools/primer-tm-calculator. Accessed today.
BibTeX
@misc{abdulfattah_primer_tm_calculator_2026,
author = {Abdulfattah, Mustafa A.},
title = {Primer Tm Calculator},
year = {2026},
url = {https://www.mustafaabdulfattah.com/tools/primer-tm-calculator},
note = {Accessed today}
}FAQ
Primer Tm Calculator questions
What is the Wallace rule?↑
The Wallace rule estimates Tm as 2 degrees for A/T bases and 4 degrees for G/C bases.
What bases are accepted?↑
The calculator accepts A, T, G, and C. Ambiguous bases trigger a warning.
Is this enough for final primer design?↑
It is useful for quick screening, but final design should consider salt, primer concentration, specificity, and secondary structure.
What else should I check?↑
Check GC content, primer length, primer dimers, hairpins, and target specificity.