Primer Analyzer: Tm, Hairpin, Dimer and Detailed Metrics

Compare vs IDT

Use this page when a basic Tm calculator is not enough. Analyze a primer in one pass for nearest-neighbor Tm, GC%, molecular weight, extinction coefficient, hairpin risk, self-dimer and hetero-dimer risk, BLAST specificity checking, and mismatch effects. If you are comparing assumptions against IDT OligoAnalyzer, this page provides detailed client-side metrics with no account required. If you only need a vendor-style Tm value, use the Tm Calculator; if structure risk is the main question, use the Secondary Structure Predictor. Use the Tm method review and the ΔG threshold reference when you need calculation references.

What it checks

Tm, GC%, MW, extinction coefficient, hairpin, self-dimer, hetero-dimer, mismatch effects, and BLAST specificity checking.

What output you get

Detailed metrics, threshold context, reverse complement, OD conversions, and structure-risk signals for lab review.

IDT relation

Compare outputs when checking assumptions against IDT OligoAnalyzer; use vendor tools when ordering or modification catalogs decide the final choice.

Privacy

Calculations run in the browser with no account requirement, making it fit for sensitive primer review.

Example input: paste a 5' to 3' primer such as ATGCGTACGTTAGCCTGA, choose PCR or qPCR settings, then run Analyze for all-in-one output. Use single-metric pages only when one result needs a deeper explanation.

Sequence

Add sequence modifications when they affect the design.

Bases 0

Analyze sequences in batch

Use batch QC for larger primer or oligo sets.

Parameters

µM
mM
mM
mM

Choose a function

Enter a sequence and select an analysis function to see results.

What Is the Primer Analyzer?

Use the Primer Analyzer when you need a single page to review primer Tm, GC%, molecular weight, hairpins, self-dimers, hetero-dimers, mismatch effects, and BLAST specificity checking before ordering or troubleshooting primers.

Paste a 5' to 3' primer, choose SpecSheet, PCR, qPCR, or Custom conditions, then review thermodynamics, base composition, mass, concentration conversion, complement sequence, and structure-risk signals without creating an account.

If you are comparing assumptions against IDT OligoAnalyzer, use this page as a browser-based primer review screen. Use vendor tools when ordering, modifications, or catalog-specific options determine the final decision. If the task is only melting temperature, use the Tm Calculator instead.

Use the Primer Analyzer when a basic Tm calculator is not enough and you need an all-in-one oligo analyzer for PCR or qPCR primer validation. In one review it reports nearest-neighbor Tm, GC content, molecular weight, extinction coefficient, OD conversions, reverse complement sequence, and structure risk signals.

For each primer, the analyzer can also run hairpin, self-dimer, hetero-dimer, BLAST specificity checking, and Tm mismatch analysis. This makes it useful when you want detailed metrics before ordering a primer, troubleshooting a failed PCR, or comparing a design against another primer-analysis tool without opening several separate pages.

The tool supports SpecSheet, PCR, qPCR, and Custom presets so the readouts match your actual buffer assumptions instead of generic defaults. The Tm output uses nearest-neighbor thermodynamic calculations, while the structure checks help you judge whether a low ΔG value is likely to be acceptable or risky under your reaction conditions.

How to Use the Primer Analyzer

  1. Enter your primer sequence (5' to 3') in the input field. Both DNA and RNA sequences are accepted.
  2. Select a parameter preset (SpecSheet, PCR, qPCR, or Custom) that matches your application.
  3. Review the real-time property readouts as you type.
  4. Review the results panel: Tm values, GC%, molecular weight, extinction coefficient, and OD conversions.
  5. Use Hairpin to check for stem-loop formation, Self-Dimer for self-complementarity, and Hetero-Dimer for compatibility with a second primer.
  6. Use BLAST to search your primer against NCBI databases for specificity review.
  7. Open the dedicated GC, molecular-weight, Tm, or structure pages when one metric needs deeper interpretation.

Frequently Asked Questions

Is this a good IDT OligoAnalyzer alternative for primer analysis?
Yes for many single-primer and primer-pair review tasks. This page covers the core checks researchers usually want from OligoAnalyzer-style output: nearest-neighbor Tm, GC%, molecular weight, extinction coefficient, hairpin risk, self-dimer and hetero-dimer checks, BLAST specificity checking, and mismatch analysis. It runs in the browser with no account requirement. IDT may still fit better when you want its ordering ecosystem or broader modification catalog.
Can I get detailed primer output here?
The Primer Analyzer is built for detailed primer review: it returns Tm, GC%, molecular weight, extinction coefficient, OD conversion values, reverse complement context, hairpin, self-dimer, hetero-dimer, mismatch effects, and BLAST specificity options. Use it when you need one lab review screen before ordering or troubleshooting primers.
What should I enter before using the Primer Analyzer?
Enter a primer sequence in 5' to 3' orientation, choose DNA or RNA, select the parameter preset closest to your experiment, and set Na+, Mg2+, dNTP, oligo concentration, and modifications if they matter. Example input: ATGCGTACGTTAGCCTGA. If you only need one metric after the all-in-one review, open the dedicated Tm, GC, molecular-weight, or structure page for deeper interpretation.
Which Tm value should I trust for PCR primer decisions?
Use the nearest-neighbor Tm as your primary decision metric for PCR and qPCR work. In this tool, Basic and Salt-adjusted values are best treated as quick context checks rather than the final answer. Choose the PCR or qPCR preset whenever possible so Na+, Mg2+, dNTP, and oligo concentration assumptions stay close to your real reaction conditions.
What makes a good PCR primer?
Good PCR primers commonly fall in these ranges: 18-25 bases, nearest-neighbor Tm around 58-62°C, GC content around 40-60%, no long homopolymer runs, a modest 3' GC clamp, no stable hairpins, no strong self-dimers, and primer-pair Tm values close to each other. The analyzer reports these criteria as a design screen; confirm assay-critical primers experimentally.
How do I design primers for GC-rich templates?
GC-rich templates (>65% GC) present challenges: primers will have high Tm and strong secondary structures. Strategies: (1) use shorter primers (18-20 nt) to keep Tm reasonable; (2) add DMSO (2-5%) or betaine (1-1.5 M) to destabilize secondary structures; (3) use high-fidelity polymerases optimized for GC-rich templates (e.g., KAPA HiFi, Q5); (4) increase denaturation temperature to 98°C; (5) open the Secondary Structure Predictor with DMSO correction to verify structure destabilization.
What is Tm mismatch analysis?
Tm mismatch analysis calculates how Tm changes when one or more bases in the primer do not match the template (mismatches). This is useful for: (1) designing allele-specific primers where the 3' base is mismatched against one allele; (2) evaluating primer specificity — how much does Tm drop with 1, 2, or 3 mismatches at different positions; (3) designing degenerate primers where IUPAC ambiguity codes represent multiple possible bases. A mismatch at the 3' end has the greatest impact on priming efficiency.

Related Tools

Tm Calculator

Use the dedicated Tm calculator when you need batch analysis, buffer-specific control, or a Tm-focused result.

Secondary Structure Predictor

Use the dedicated structure page when the main task is a hairpin calculator, primer dimer check, or ΔG threshold decision.

Molecular Weight Calculator

Open the MW calculator when you only need mass, extinction coefficient, and OD260 conversion details.

GC Content Analyzer

Use the GC calculator when base composition, GC clamp, or extreme GC content is the main design question.

Review request

Check a result or ordering detail

Send the calculation, settings, or pool submission detail that needs a second look.

Related reading

Continue with the page or tool that matches the next decision in your experiment.

Tm Method ReviewΔG Threshold Method ReferenceSecondary Structure TutorialOligoPool vs IDT OligoAnalyzer