FISH Probe Melting Temperature (Tm) Calculator
Estimate the melting temperature (Tm) of a fish probe — Wallace rule for ≤13 nt, basic GC formula for longer oligos. Balance forward/reverse primer Tm within ~5°C.
- 1Counts: A=5 T/U=5 G=6 C=5 (n=21)
- 2Tm by basic GC (Marmur–Doty)
Tm = 54.4 °C
🔒 100% client-side — your data is computed in the browser and never uploaded.
Cite this tool
ToolJolt. FISH Probe Melting Temperature (Tm) Calculator. ToolJolt Chemistry & Lab Tools; 2026. https://tooljolt.comFISH Probe Melting Temperature (Tm) Calculator for molecular biologists, geneticists and bioinformaticians. Enter your values and read a sourced, step-by-step result instantly, right in your browser.
About FISH Probe Melting Temperature (Tm) Calculator
Estimate the melting temperature (Tm) of a fish probe — Wallace rule for ≤13 nt, basic GC formula for longer oligos. Balance forward/reverse primer Tm within ~5°C. The calculation uses Tm: 2(A+T)+4(G+C) or 64.9+41(GC−16.4)/N. Why accuracy here pays off: Primer design, GC content and melting temperature decide whether a PCR amplifies cleanly or produces nothing. Small sequence mistakes propagate into failed experiments and wasted reagents. Match the Tm of paired primers for efficient amplification. Mistakes that trip people up: reading the wrong strand or frame; mismatched forward/reverse primer Tm; primers with runs of G/C causing mispriming. No account, no upload, no tracking of your inputs — the result is generated on your machine, which makes it reproducible, private and citable in published work.
How to use FISH Probe Melting Temperature (Tm) Calculator
- 1Enter your input values.
- 2Read the headline result and the supporting figures, which recompute as you type.
- 3Open “Worked example with your numbers” to see the substituted formula step by step.
- 4Copy the result, or use the cite-this-tool snippet for your methods section.
Why use FISH Probe Melting Temperature (Tm) Calculator?
- ✓Designed for molecular biologists, geneticists and bioinformaticians who need a trustworthy answer fast
- ✓Instant, client-side result — works offline once loaded and keeps your data private
- ✓Shows the worked example step by step with your own numbers, not just a final figure
- ✓Pre-filled with sensible, niche-specific defaults so it is useful the second it loads
- ✓Mobile-friendly and completely free, with no sign-up or usage caps
Frequently asked questions
Any tips specific to this calculation?+
Match the Tm of paired primers for efficient amplification. Also watch out for: reading the wrong strand or frame and ignoring secondary structure in GC-rich templates.
Is this fish probe melting temperature (tm) calculator free to use?+
Yes. It is completely free, needs no sign-up, and runs entirely in your browser — there are no usage limits.
What formula does it use?+
It uses Tm: 2(A+T)+4(G+C) or 64.9+41(GC−16.4)/N The full worked example is shown beneath the result so you can verify each step.
What are the most common mistakes here?+
In nucleic-acid sequence analysis, watch for: mismatched forward/reverse primer Tm; primers with runs of G/C causing mispriming; ignoring secondary structure in GC-rich templates; reading the wrong strand or frame. This tool shows the working so you can catch these before they cost an experiment.
Does my data leave my device?+
No. All computation happens locally in your browser. Nothing you enter — sequences, concentrations or measurements — is uploaded to any server, so it is safe for confidential work.
Can I cite this tool?+
Yes — use the “Cite this tool” snippet on the page. Many users link these calculators from methods sections, lab SOPs and teaching materials.
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