{
  "id": "transformation-efficiency",
  "version": "014149a9e5a3",
  "status": "published",
  "name": "Transformation Efficiency Calculator",
  "question": "What is transformation efficiency?",
  "summary": "Finds the transformation efficiency of competent cells, in colony-forming units per microgram of DNA, from the colonies counted, the DNA transformed and the share of the transformation that was plated, or the colonies to expect from a known efficiency.",
  "category": "biology",
  "subcategory": "lab",
  "url": "https://www.acalculator.org/biology/transformation-efficiency-calculator",
  "markdown": "https://www.acalculator.org/biology/transformation-efficiency-calculator.md",
  "kind": "function",
  "method": "TE = colonies ÷ (µg of DNA transformed × fraction plated); fraction plated = volume plated ÷ (total volume after recovery × extra dilution); expected colonies = TE × µg × fraction plated.",
  "assumptions": [
    "Every colony on the counted plate grew from one transformed cell, and the plate is countable (not a lawn).",
    "The total volume is the cells plus the recovery medium; the few µL of DNA added are left out, as in NEB’s examples."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "find": {
        "title": "Find",
        "description": "The efficiency from a colony count, or the colonies to expect from an efficiency.",
        "type": "string",
        "enum": [
          "te",
          "col"
        ]
      },
      "c": {
        "title": "Colonies counted",
        "description": "The colonies on the plate you counted.",
        "type": "integer",
        "minimum": 0,
        "maximum": 1000000000
      },
      "te": {
        "title": "Efficiency (cfu/µg)",
        "description": "The transformation efficiency of the cells, such as 1e8 colony-forming units per µg.",
        "type": "number",
        "minimum": 0.000001,
        "maximum": 1000000000000000
      },
      "dna": {
        "title": "DNA transformed",
        "description": "The amount of plasmid DNA added to the competent cells.",
        "type": "number",
        "minimum": 0.000001,
        "maximum": 1000000000
      },
      "u": {
        "title": "DNA unit",
        "description": "Picograms, nanograms or micrograms of DNA.",
        "type": "string",
        "enum": [
          "pg",
          "ng",
          "ug"
        ]
      },
      "how": {
        "title": "Share plated from",
        "description": "Work out the share of the DNA that was plated from the volumes, or type it.",
        "type": "string",
        "enum": [
          "vol",
          "frac"
        ]
      },
      "vt": {
        "title": "Total volume after recovery (µL)",
        "description": "Competent cells plus the recovery medium (SOC), such as 50 + 950 = 1,000 µL.",
        "type": "number",
        "minimum": 0.001,
        "maximum": 1000000
      },
      "x": {
        "title": "Extra dilution before plating (1 in …)",
        "description": "A further dilution of the recovered cells before plating: 100 for 10 µL taken up to 1 mL; 1 for none.",
        "type": "number",
        "minimum": 1,
        "maximum": 1000000000
      },
      "vp": {
        "title": "Volume plated (µL)",
        "description": "The volume spread on the plate you counted.",
        "type": "number",
        "minimum": 0.001,
        "maximum": 1000000
      },
      "f": {
        "title": "Fraction of the DNA plated",
        "description": "The share of the transformation that went on the plate, such as 0.1; the product of each dilution step.",
        "type": "number",
        "minimum": 1e-12,
        "maximum": 1
      }
    }
  },
  "outputs": {
    "result": {
      "label": "Answer",
      "description": "The efficiency in cfu per µg of DNA, or the colonies to expect.",
      "format": "text"
    },
    "efficiency": {
      "label": "Transformation efficiency (cfu/µg)",
      "description": "Colonies ÷ µg of DNA ÷ the fraction plated.",
      "format": "number"
    },
    "expected": {
      "label": "Expected colonies",
      "description": "The efficiency × µg of DNA × the fraction plated.",
      "format": "number"
    },
    "dnaUg": {
      "label": "DNA transformed (µg)",
      "description": "The DNA added to the cells, in micrograms.",
      "format": "number"
    },
    "share": {
      "label": "Fraction plated",
      "description": "The share of the transformation on the plate: volume plated ÷ (total volume × dilution).",
      "format": "number"
    },
    "onPlate": {
      "label": "DNA on the plate (µg)",
      "description": "The micrograms of DNA that went on the plate: µg transformed × the fraction plated.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "find": "te",
      "c": 20,
      "te": 100000000,
      "dna": 100,
      "u": "pg",
      "how": "vol",
      "vt": 1000,
      "x": 1,
      "vp": 100,
      "f": 0.1
    },
    "outputs": {
      "result": "TE = 2 × 10⁶ cfu/µg",
      "efficiency": 2000000,
      "dnaUg": 0.0001,
      "share": 0.1,
      "onPlate": 0.00001
    },
    "text": "TE = 2 × 10⁶ cfu/µg."
  },
  "examples": [
    {
      "given": {
        "find": "te",
        "c": 20,
        "dna": 100,
        "u": "pg",
        "how": "vol",
        "vt": 1000,
        "vp": 100
      },
      "expect": {
        "efficiency": 2000000,
        "share": 0.1,
        "onPlate": 0.00001,
        "result": "TE = 2 × 10⁶ cfu/µg"
      },
      "source": "NEB, FAQ: How should I calculate the transformation efficiency (C2925)? (TE = Colonies/µg/Dilution; 20 colonies from 100 pg, 100 µl of 1,000 µl plated: 2 × 10⁶ cfu/µg), https://www.neb.com/en-us/faqs/how-should-i-calculate-the-transformation-efficiency-c2925; Python 3"
    },
    {
      "given": {
        "find": "te",
        "c": 150,
        "dna": 100,
        "u": "pg",
        "how": "vol",
        "vt": 300,
        "x": 100,
        "vp": 30
      },
      "expect": {
        "efficiency": 1500000000,
        "share": 0.001,
        "result": "TE = 1.5 × 10⁹ cfu/µg"
      },
      "source": "NEB, FAQ: How should I calculate the transformation efficiency (C3040)? (150 colonies from 100 pg; dilution 10/300 × 30/1000 = 0.001: 1.5 × 10⁹ cfu/µg), https://www.neb.com/en-us/faqs/how-should-i-calculate-the-transformation-efficiency; Python 3"
    },
    {
      "given": {
        "find": "te",
        "c": 50,
        "dna": 1,
        "u": "ng",
        "how": "frac",
        "f": 0.05
      },
      "expect": {
        "efficiency": 1000000,
        "onPlate": 0.00005
      },
      "source": "NEB, FAQ: How should I calculate the transformation efficiency (C2925)? (TE = Colonies/µg/Dilution; 20 colonies from 100 pg, 100 µl of 1,000 µl plated: 2 × 10⁶ cfu/µg), https://www.neb.com/en-us/faqs/how-should-i-calculate-the-transformation-efficiency-c2925: TE = Colonies/µg/Dilution; hand calculation in content.mdx: 50 ÷ 0.001 ÷ 0.05; Python 3"
    },
    {
      "given": {
        "find": "col",
        "te": 100000000,
        "dna": 10,
        "u": "pg",
        "how": "frac",
        "f": 0.1
      },
      "expect": {
        "expected": 100,
        "result": "100 colonies expected"
      },
      "source": "NEB, FAQ: How should I calculate the transformation efficiency (C2925)? (TE = Colonies/µg/Dilution; 20 colonies from 100 pg, 100 µl of 1,000 µl plated: 2 × 10⁶ cfu/µg), https://www.neb.com/en-us/faqs/how-should-i-calculate-the-transformation-efficiency-c2925, the equation solved for the colonies; hand calculation in content.mdx: 10⁸ × 0.00001 × 0.1; Python 3"
    }
  ],
  "sources": [
    "NEB, FAQ: How should I calculate the transformation efficiency (C2925)?: TE = Colonies/µg/Dilution, with 100 pg, 50 µL of cells, 950 µL of SOC, 100 µL plated and 20 colonies giving 2 × 10⁶ cfu/µg. https://www.neb.com/en-us/faqs/how-should-i-calculate-the-transformation-efficiency-c2925 (retrieved 2026-10-19)",
    "NEB, FAQ: How should I calculate the transformation efficiency (C3040)?: dilution 10/300 × 30/1000 = 0.001, 150 colonies from 100 pg giving 1.5 × 10⁹ cfu/µg. https://www.neb.com/en-us/faqs/how-should-i-calculate-the-transformation-efficiency (retrieved 2026-10-19)",
    "Addgene, Protocol: Bacterial Transformation: 1 to 5 µL of DNA (10 pg to 100 ng) into 20 to 50 µL of cells, 250 to 1,000 µL of SOC, plating 50 µL and the rest, ligations about 10-fold less efficient. https://www.addgene.org/protocols/bacterial-transformation/ (retrieved 2026-10-19)"
  ],
  "related": [
    "serial-dilution",
    "centrifuge",
    "tm",
    "reverse-complement"
  ],
  "changelog": []
}