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Primer Tm & GC%: Make Your PCR Actually Work

Annealing temperature, GC clamps and why a 5°C Tm mismatch kills your reaction — design primers that amplify.

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PCR Primer Melting Temperature (Tm) Calculator

Estimate the melting temperature (Tm) of a pcr primer — Wallace rule for ≤13 nt, basic GC formula for longer oligos. Balance forward/reverse primer Tm within ~5°C.

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qPCR Primer Melting Temperature (Tm) Calculator

Estimate the melting temperature (Tm) of a qpcr primer — Wallace rule for ≤13 nt, basic GC formula for longer oligos. Balance forward/reverse primer Tm within ~5°C.

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Cloning Primer Melting Temperature (Tm) Calculator

Estimate the melting temperature (Tm) of a cloning primer — Wallace rule for ≤13 nt, basic GC formula for longer oligos. Balance forward/reverse primer Tm within ~5°C.

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PCR Primer GC Content Calculator

Calculate the GC content (%) of primer quality (aim 40–60%). GC% drives melting temperature, secondary structure and PCR behaviour.

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PCR Amplicon GC Content Calculator

Calculate the GC content (%) of an expected amplicon. GC% drives melting temperature, secondary structure and PCR behaviour.

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Plasmid GC Content Calculator

Calculate the GC content (%) of a plasmid backbone. GC% drives melting temperature, secondary structure and PCR behaviour.

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PCR Primer Reverse Complement Tool

Generate the reverse complement (5′→3′) of a PCR Primer sequence — for designing the reverse primer. Runs in your browser; the sequence is never uploaded.

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DNA GC Content Calculator

Calculate the GC content (%) of genomic or any DNA. GC% drives melting temperature, secondary structure and PCR behaviour.

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