ΔΔCt qPCR Relative Expression Calculator
Fold change of every target against your calibrator, with replicate error bars.
Try before you buy.
- Free preview: input labels and masked result rows; computed charts and complete exports stay locked.
- Locked until you unlock it: download and copy.
- Unlock: Pro pass, ₹179 for 30 days or ₹79 for 1 week, a one-time payment that never renews. Unlock: Pro pass, $5.99 for 30 days or $2.99 for 1 week, a one-time payment that never renews.
Ways to unlock shows how to get the full result.
Printing this result is locked in the free preview.
Locked in the free preview. Opens the ways to unlock this result.
Locked in the free preview. Batch runs unlock with a pass.
Locked in the free preview. Query results unlock with a pass.
About the ΔΔCt qPCR Relative Expression Calculator
Analyse a whole plate of measured wells, with any number of samples, target genes, reference genes and technical replicates. Ct values are averaged within each sample and gene before the calibrator-relative expression is calculated, by the 2^−ΔΔCt method or by Pfaffl’s efficiency-corrected method, and every result has a log-scale error bar whose meaning is stated.
The free preview shows the report’s rows with the computed values hidden; a Pro pass shows every value and chart, with copy and CSV, SVG or PDF downloads. Give each biological specimen its own sample name. Amplification efficiency, reference-gene stability and assay quality must be validated separately; the calculator does not diagnose, certify an assay or claim MIQE compliance.
How to use it
- Paste or upload all measured wells, and name the columns for sample, gene, Ct, role (target or reference) and, if you have them, amplification factors.
- Name the calibrator sample and choose ΔΔCt or Pfaffl. A factor is the multiplier per cycle (2 is a perfect doubling), not an efficiency percentage.
- For one slope per gene, choose factors from the slopes; otherwise give each gene its measured factor in the CSV.
- Select Calculate to check every sample, Ct mean, replicate count, fold change and error bar; with a Pro pass, download the tables, charts and PDF.
Examples
Control: target Ct 25, reference Ct 20; treated: target Ct 23, reference Ct 20; factor 2
ΔΔCt −2, fold change 4
Technical replicates are averaged before the exponent is taken.
Method and sources
ΔCt = mean target Ct − mean reference Ct; ΔΔCt = sample ΔCt − calibrator ΔCt; fold change = 2^−ΔΔCt when every gene doubles each cycle. Pfaffl’s ratio is target factor^(calibrator − sample target Ct) divided by the geometric mean of reference factor^(calibrator − sample reference Ct). A factor from a standard-curve slope is 10^(−1/slope), and the efficiency is factor − 1. See Livak and Schmittgen’s method and Pfaffl’s model.
Limitations
- Ct replicates are treated as unpaired technical measurements of one biological sample; paired-well covariance and biological inference are not modelled.
- Error bars are ±1 propagated standard error on the log scale, assuming independent group means and fixed amplification factors; they are not prediction intervals or biological confidence intervals.
- A group with a single replicate has no estimated measurement error. Blank and Undetermined wells are never treated as Ct 0.
- ΔΔCt assumes a factor of 2 for every gene, which needs suitable amplification. Reference-gene stability and the validated range are for your experiment to establish.
- PDF reports load their font from this site. A label the font cannot show gives a clear PDF error; the CSV, text and SVG files keep every label as you typed it.
Privacy
On this device: nothing is sent
Your data, the fits and the exports stay on this device. Only the report font loads from this site; nothing is uploaded and no AI is used.
Frequently asked questions
What do I get without a pass?
Without a pass, ΔΔCt qPCR Relative Expression Calculator shows input labels and masked result rows; computed charts and complete exports stay locked. Until you unlock it, the result can’t be downloaded or copied. A Pro, Premium or Ultimate pass, a one-time payment that never renews, unlocks the full result. The pricing page lists the passes and their prices.
Does this validate my experiment?
No. It calculates from the data you entered with the model it states. Check your sampling, the assay’s assumptions and independent controls.
Is there a limit on the number of wells?
No. Enter every well you measured; only your device’s memory limits a very large file.
What happens to a blank or invalid row?
It gets an error that names the row. A blank or an unquantified reading is never treated as zero or dropped silently.