How to use the primer melting temperature calculator
Estimate Tm and annealing temperature of a PCR primer. Enter primer sequence in the field above; the length, gc content, melting temperature tm, suggested annealing temperature are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- seq — Primer sequence
Worked example
With primer sequence = ATGCGTACGTTAGCAT, the calculator gives length ≈ 16 nt; gc content ≈ 43.75 %; melting temperature tm ≈ 40.8125 °C; suggested annealing temperature ≈ 35.8125 °C.
Frequently asked questions
What is the formula for the primer melting temperature calculation?
Length (nt) = clean(seq).length. GC content (%) = gcPct(seq). Melting temperature Tm (°C) = tm(seq). Suggested annealing temperature (°C) = [Melting temperature Tm]-5. Here seq is primer sequence.
What inputs do I need for the primer melting temperature calculator?
You need primer sequence. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.