qPCR Livak 2^(−ΔΔCt) Relative Gene Expression Fold-Change Calculator

Normalize RT-qPCR target cycle thresholds (Ct) against housekeeping controls.

Relative Expression Fold Change (2^−ΔΔCt)
5.66 fold
ΔΔCt (ΔCt_treated − ΔCt_control) -2.5 cycles
Log₂ Fold Change (−ΔΔCt) 2.5 log₂ FC
Treated Normalized ΔCt 3.2 cycles
Inputs
Ct
Treated sample target gene Ct value.
Ct
Treated sample housekeeping reference gene Ct value.
Ct
Untreated calibrator control target gene Ct value.
Ct
Untreated calibrator control reference gene Ct value.
Results & Graph
Relative Expression Fold Change (2^−ΔΔCt)
5.66 fold
ΔΔCt (ΔCt_treated − ΔCt_control)
-2.5 cycles
Log₂ Fold Change (−ΔΔCt)
2.5 log₂ FC
Treated Normalized ΔCt
3.2 cycles

Relative Expression Fold Change (2^−ΔΔCt)

Graph 1 • Treated Target Ct Sensitivity Recalculates the domain equation across 50% to 150% of the primary input while holding other parameters constant.
0 fold 5.1k fold 10.2k fold 50%: 9,410.14 fold 9.4k 50% 75%: 230.72 fold 230.7 75% 100%: 5.66 fold 5.7 100% 125%: 0.14 fold 0.1 125% 150%: 0 fold 0 150%
Graph 2 • Primary & Supporting Metric Comparison Compares the primary output alongside supporting domain benchmarks.
Relative Expression Fold Change (2^−ΔΔCt) 5.66 fold ΔΔCt (ΔCt_treated − ΔCt_control) -2.5 cycles Log₂ Fold Change (−ΔΔCt) 2.5 log₂ FC Treated Normalized ΔCt 3.2 cycles
Graph 3 • Exact Output Table & Units Displays each calculated output in its exact domain unit.
Relative Expression Fold Change (2^−ΔΔCt)5.66 foldΔΔCt (ΔCt_treated − ΔCt_control)-2.5 cyclesLog₂ Fold Change (−ΔΔCt)2.5 log₂ FCTreated Normalized ΔCt3.2 cycles
Summary: ΔCt_treated = 3.2, ΔCt_control = 5.7, and ΔΔCt = -2.5, yielding a 5.66-fold relative gene expression change.
Summary: ΔCt_treated = 3.2, ΔCt_control = 5.7, and ΔΔCt = -2.5, yielding a 5.66-fold relative gene expression change.
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Formula & Mathematical Methodology: qPCR 2^(−ΔΔCt) Fold Change Reference Equation

ΔCt = Cttarget − Cthousekeeping
ΔΔCt = ΔCttreated − ΔCtcontrol
FoldChange = 2−ΔΔCt
ΔCt = Ct_target − Ct_housekeeping; ΔΔCt = ΔCt_treated − ΔCt_control; FoldChange = 2^(−ΔΔCt)
  • treatedTargetCt: Treated Target Ct (Ct)
  • treatedReferenceCt: Treated Reference Ct (Ct)
  • controlTargetCt: Control Target Ct (Ct)
  • controlReferenceCt: Control Reference Ct (Ct)

Rounding: Laboratory and clinical equations retain full floating-point precision and round displayed results to 2 decimal places.

Worked Example: Reference Calculation: qPCR 2^(−ΔΔCt) Fold Change

Normalize RT-qPCR target cycle thresholds (Ct) against housekeeping controls.

  1. Enter the reagent concentrations, assay readings, or clinical laboratory parameters.
  2. Compute the standard formula: ΔCt = Ct_target − Ct_housekeeping; ΔΔCt = ΔCt_treated − ΔCt_control; FoldChange = 2^(−ΔΔCt).
  3. Review the primary result, supporting reference intervals, and 3 SVG visualizations.
Result: Evaluates qPCR 2^(−ΔΔCt) Fold Change via ΔCt = Ct_target − Ct_housekeeping; ΔΔCt = ΔCt_treated − ΔCt_control; FoldChange = 2^(−ΔΔCt).

Frequently Asked Questions

What formula is used by the qPCR Livak 2^(−ΔΔCt) Relative Gene Expression Fold-Change Calculator?

It computes ΔCt = Ct_target − Ct_housekeeping; ΔΔCt = ΔCt_treated − ΔCt_control; FoldChange = 2^(−ΔΔCt) and plots three custom SVG graphs showing parameter sensitivity and component breakdowns.

Can I compare different reagent dilutions or lab scenarios side by side?

Yes. Use the "Compare (0/3)" button to pin up to 3 scenarios side by side.

Are entered values stored on any server?

No. Every calculation runs 100% locally in your browser.

Science & Engineering · Molecular Biology & Genetics

qPCR Livak 2^(−ΔΔCt) Relative Gene Expression Fold-Change Calculator: inputs, method, and how to read the result

Normalize RT-qPCR target cycle thresholds (Ct) against housekeeping controls.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Treated Target Ct: Treated sample target gene Ct value.
  • Treated Reference Ct: Treated sample housekeeping reference gene Ct value.
  • Control Target Ct: Untreated calibrator control target gene Ct value.
  • Control Reference Ct: Untreated calibrator control reference gene Ct value.

What the calculation includes

With the default values shown, Relative Expression Fold Change (2^−ΔΔCt) is 5.66 fold. The calculation follows qPCR 2^(−ΔΔCt) Fold Change Reference Equation; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Treated Target Ct from 21.4 Ct to 23.54 Ct changes Relative Expression Fold Change (2^−ΔΔCt) from 5.66 fold to 1.28 fold. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard IUPAC atomic weights, 25°C (298.15 K) reference thermodynamics, and published clinical literature equations.
  • Educational and laboratory reference tool only; clinical scoring calculators do not replace professional medical judgment or institutional protocols.

Scope: IUPAC / NIH Laboratory & Clinical Reference Standard Check the assumptions and limitations against your situation before relying on the estimate.

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