Transformation Efficiency Calculator
🧬 Transformation Results
Transformation Efficiency
—
Total Transformants
—
CFU in recovery volume
Average Colony Count
—
colonies on plate
CFU/mL
—
in recovery volume
Log₁₀ Efficiency
—
log CFU/µg
How to Use the Transformation Efficiency Calculator
Enter your plate colony count, the dilution used, the volume plated, the total recovery volume after transformation, and the amount of DNA used. The calculator outputs transformation efficiency in CFU/µg DNA.
- Colony Count: Colonies on your selective antibiotic plate after overnight incubation.
- Volume Plated: The volume spread on the plate (µL), typically 100–200 µL.
- Total Recovery Volume: The full volume of cells after outgrowth (µL), typically 1000 µL (1 mL).
- DNA Amount: Amount of plasmid DNA used in the transformation reaction (ng). Convert to µg for the final result.
Transformation Efficiency Formula
CFU/mL = (Colonies × Dilution Factor⁻¹) / (Volume Plated in mL)
Total Transformants = CFU/mL × Total Recovery Volume (mL)
TE (CFU/µg) = Total Transformants / DNA amount (µg)
Example:
Colonies = 250, Dilution = 1, Plated = 0.1 mL, Total = 1 mL, DNA = 1 ng
CFU/mL = 250 / 0.1 = 2500
Total = 2500 × 1 = 2500 CFU
TE = 2500 / 0.001 µg = 2.5 × 10⁶ CFU/µg
Total Transformants = CFU/mL × Total Recovery Volume (mL)
TE (CFU/µg) = Total Transformants / DNA amount (µg)
Example:
Colonies = 250, Dilution = 1, Plated = 0.1 mL, Total = 1 mL, DNA = 1 ng
CFU/mL = 250 / 0.1 = 2500
Total = 2500 × 1 = 2500 CFU
TE = 2500 / 0.001 µg = 2.5 × 10⁶ CFU/µg
Transformation Efficiency Benchmarks
- > 10⁸ CFU/µg: Excellent — electrocompetent cells or high-quality commercial competent cells.
- 10⁶ – 10⁸ CFU/µg: Good — typical for chemically competent cells (heat shock).
- 10⁴ – 10⁶ CFU/µg: Acceptable — home-made competent cells or suboptimal conditions.
- < 10⁴ CFU/µg: Poor — check cell competency, DNA quality, heat shock time/temperature.