qPCR ΔΔCt Calculator (2^-ΔΔCt fold change)

Paste Sample, Gene and Ct values from Excel or your instrument and get mean Ct, ΔCt, ΔΔCt and fold change with error ranges. Export to CSV. Data never leaves your browser.

Paste three columns: Sample, Gene, Ct (copy straight from Excel or your instrument export). Technical replicates are averaged.

Your data stays in your browser — nothing is uploaded, so it is safe for unpublished results.

Reference (housekeeping) gene

Control / calibrator sample

Sample	Gene	Ct target	Ct reference	ΔCt	ΔΔCt	Fold change	Range (±SD)

How it works

Uses the Livak 2^-ΔΔCt method. Technical replicates are averaged first. ΔCt = mean Ct(target) − mean Ct(reference gene); ΔΔCt = ΔCt(sample) − ΔCt(control sample); fold change = 2^-ΔΔCt. The error range is 2^-(ΔΔCt ± SD), where SD of ΔCt = √(SD_target² + SD_reference²). The method assumes primer efficiencies close to 100% for both genes; validate this with a standard curve before relying on the results.

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