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PCR & qPCR Primer Design Tool

Generate research-oriented primer pairs from a DNA template using configurable amplicon size, melting-temperature and GC-content ranges. Candidate pairs are returned with sequence-level quality metrics and optional local specificity screening against background FASTA sequences.

Primer3-based design Tm & GC control Hairpin & dimer metrics Local background screen
Double-stranded DNA template 5′ 3′ 3′ 5′ Forward primer 5′ → 3′ extension Reverse primer 5′ → 3′ extension Amplicon = sequence between the two primer 5′ ends
Primer-pair anatomy. The primers face each other and define the boundaries of the amplified product.

Design workspace

Research use
1

DNA template

Paste a DNA sequence using A, C, G, T or N.

Longer, clean template sequence gives Primer3 more freedom to identify suitable primer pairs.
2

Design parameters

Define amplicon size, melting-temperature range, GC range and the number of pairs returned.

Lower amplicon-size boundary
Upper amplicon-size boundary
Number of candidate pairs
Lower accepted primer Tm
Primer3 target Tm
Upper accepted primer Tm
Lowest accepted GC content
Highest accepted GC content
Label used with saved design work when supported
3

Optional specificity background

Supply sequences you specifically want to rule out.

Local screening evaluates only the background sequences supplied here; it is not a genome-wide specificity analysis.
Why matched Tm matters. Both primers experience the same annealing temperature in one PCR tube. Primer pairs with similar melting temperatures are therefore easier to optimize than pairs with widely separated Tm values.
Primer predictions should be experimentally validated before use.

Primer Design Results

Compare candidate pairs by sequence, amplicon size, Tm, GC content, secondary-structure metrics, quality score and local specificity information.

Technical API response 

    

  




  

  

    
Primer Secondary Structures

    
Hairpins, self-dimers and heterodimers can compete with productive primer–template binding.


    


      

        
          A. Hairpin
          
          
          
          Intramolecular complementarity folds the primer back on itself.

          B. Self-dimer
          
          
          
          
          
          
          Two copies of the same primer pair with each other.
        
        

          Hairpins use complementarity within one primer; self-dimers use complementarity between two copies of the same primer.
        

      


      

        
          C. Heterodimer / cross-dimer

          Forward 5′
          
          
          3′

          Reverse 5′
          
          
          3′

          
          3′ complementarity is the highest-risk region
          If the two primers pair through extendable 3′ ends, they can create an amplifiable primer-dimer.

          
          Interpret structure Tm relative to the intended annealing conditions; lower-risk structures are less stable.
        
        

          Heterodimers involve the forward and reverse primers. Complementarity at or very near both 3′ ends deserves special attention.
        

      

    

  


  

  

  

  

  

  

  
Research use: primer rankings and structure metrics support candidate selection; confirm specificity and performance experimentally.





    
Related Molecular Design Lab

    

      Design Assay
      Standard PCR Primer Design
      RT-qPCR Primer Design
      Peptide Analysis
      MHC / HLA Prediction
      Projects