Gene Expression Fold Change Calculator

Work out gene expression fold change instantly with clear inputs, formula shown and shareable results.

About Gene Expression Fold Change Calculator

Applies the Livak delta delta Ct method: the target is normalised to a reference gene in each sample and then compared between conditions.

Formula

Livak method

dCt = Ct target - Ct reference; ddCt = dCt treated - dCt control; fold change = 2^(-ddCt)

Worked example

With the default values below, Gene Expression Fold Change Calculator returns Fold change of 3.7321. Change any input above and every figure here is recalculated in your browser.

Inputs used

Target Ct in the treated sampleaccepts 5–45: 22.4
Reference gene Ct in the treated sampleaccepts 5–45: 19.2
Target Ct in the controlaccepts 5–45: 25.3
Reference gene Ct in the controlaccepts 5–45: 20.2

Results

Fold change: 3.7321
Delta delta Ct: -1.900
Delta Ct in the treated sample: 3.200
Direction of change: Upregulated relative to control

Step by step

1Values used
2Livak method
3Fold change= 3.7321
4Delta delta Ct= -1.900
5Delta Ct in the treated sample= 3.200
6Direction of change= Upregulated relative to control

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What does the method assume?

That target and reference amplify with equal, near-perfect efficiency; otherwise the Pfaffl method should be used.

How many reference genes are needed?

At least two validated reference genes are recommended, since single-gene normalisation is often unstable.