laboratory
Primer Melting Temperature Calculator
Calculate DNA primer Tm by Wallace or SantaLucia nearest-neighbor thermodynamics with salt, Mg²⁺, dNTP and primer-concentration correction.
Calculator
Formula
Tₘ=ΔH/(ΔS+Rln(C/4))−273.15+salt correction
Assumptions and limits
- Designed for unambiguous DNA oligos; mismatch, probe and full primer-design effects are outside this calculator.
Example
Editable worked example
The calculator starts with an editable example.
Sources
- Primer3 Manual — Primer3 Project
- Biopython SeqUtils documentation — Biopython Project
Frequently asked questions
Are my inputs uploaded?
No. This calculator runs locally in your browser. Inputs are placed in a URL only when you explicitly copy a share link.
Why are units converted first?
Canonical units prevent scale errors when inputs use mixed units. The result is converted back to your selected output unit afterward.
Does the result replace professional judgment?
No. The result applies only to the stated model and assumptions. Qualified people should review high-risk engineering, medical, or laboratory decisions.