DNA Copy Number Calculator

Convert DNA Mass to Molecule Copies

Calculate the number of DNA molecules from mass and length. Supports ng, µg, and pg. Essential for qPCR, cloning, and molecular biology workflows.

Example Calculations

Try these real-world DNA copy number calculations

Plasmid DNA, 5 ng, 3000 bp

Plasmid Standard

Calculate copy number for 5 ng of a 3000 bp plasmid.

DNA Amount: 5 ng

DNA Length (bp): 3000 bp

Output Type: Copy Number

Genomic DNA, 100 pg, 50000 bp

Genomic DNA

Calculate copy number for 100 pg of a 50,000 bp DNA fragment.

DNA Amount: 100 pg

DNA Length (bp): 50000 bp

Output Type: Copy Number

qPCR Standard, 0.2 µg, 1500 bp

qPCR Standard Curve

Calculate log10(copy number) for 0.2 µg of a 1500 bp PCR product.

DNA Amount: 0.2 µg

DNA Length (bp): 1500 bp

Output Type: Log10(Copy Number)

Oligonucleotide, 10 ng, 25 bp

Small Oligo

Calculate copy number for 10 ng of a 25 bp oligonucleotide.

DNA Amount: 10 ng

DNA Length (bp): 25 bp

Output Type: Copy Number

Other Titles
Understanding DNA Copy Number: A Comprehensive Guide
Master DNA quantification and molecular calculations with accurate copy number estimation

What is DNA Copy Number?

  • Definition and Importance
  • Molecular Biology Applications
  • Copy Number in qPCR and Cloning
DNA copy number refers to the number of individual DNA molecules present in a given sample. It is a fundamental parameter in molecular biology, essential for quantifying gene expression, preparing standard curves for qPCR, and ensuring accurate cloning and transformation experiments.
Why Copy Number Matters
Knowing the exact number of DNA molecules allows researchers to standardize experiments, compare results across samples, and ensure reproducibility in quantitative assays.
Applications in Research and Diagnostics
Copy number calculations are used in qPCR, digital PCR, gene quantification, synthetic biology, and clinical diagnostics to determine the abundance of target DNA sequences.

Copy Number Use Cases

  • qPCR standard curve preparation
  • Plasmid transformation efficiency
  • Gene copy number variation analysis

Step-by-Step Guide to Using the DNA Copy Number Calculator

  • Input DNA Amount and Unit
  • Enter DNA Length
  • Select Output Type
Our calculator makes it easy to convert DNA mass to molecule copy number. Simply enter the amount of DNA, select the appropriate unit (ng, µg, or pg), and provide the length of the DNA fragment in base pairs (bp).
Choosing the Correct Unit
Accurate results depend on using the correct unit for DNA amount. Nanograms (ng) are most common, but micrograms (µg) and picograms (pg) are also supported for flexibility.
Understanding Output Options
You can choose to display the result as the absolute copy number or as log10(copy number), which is useful for standard curve plotting in qPCR.

Step-by-Step Examples

  • 5 ng, 3000 bp plasmid: Copy Number = 1.54 x 10^9
  • 0.2 µg, 1500 bp PCR product: Log10(Copy Number) = 11.1

Real-World Applications of DNA Copy Number Calculations

  • qPCR Standard Curves
  • Plasmid Preparation
  • Gene Quantification
DNA copy number calculations are essential in many laboratory workflows. They enable accurate quantification of standards, assessment of transformation efficiency, and precise gene dosage analysis.
qPCR and Digital PCR
In quantitative PCR, knowing the exact copy number of standards is critical for generating reliable standard curves and quantifying unknown samples.
Cloning and Transformation
Calculating plasmid copy number helps optimize transformation protocols and assess the success of cloning experiments.
Gene Dosage and CNV Analysis
Copy number variation (CNV) analysis relies on accurate copy number estimation to detect genetic differences and disease associations.

Application Examples

  • Standard curve for qPCR quantification
  • Plasmid copy number in E. coli transformation
  • Gene dosage analysis in clinical genetics

Common Misconceptions and Correct Methods

  • Unit Conversion Errors
  • Incorrect DNA Length
  • Misuse of Log10 Output
Mistakes in unit conversion or DNA length entry can lead to large errors in copy number calculation. Always double-check your inputs and use the correct formula.
Unit Conversion Pitfalls
Ensure that DNA amount is converted to nanograms (ng) if using other units. 1 µg = 1000 ng, 1 pg = 0.001 ng.
DNA Length Accuracy
DNA length must be entered in base pairs (bp). Using incorrect length values will result in inaccurate copy number estimation.
Log10 Output Usage
Log10(copy number) is useful for plotting standard curves but should not be confused with the actual number of molecules present.

Best Practice Guidelines

  • Don't enter mass in µg if unit is set to ng
  • Always use full plasmid length for circular DNA
  • Use log10 only for standard curve plotting

Mathematical Derivation and Examples

  • Copy Number Formula
  • Unit Conversions
  • Worked Examples
The DNA copy number is calculated using Avogadro's constant and the average molecular weight of a base pair (650 Da). The formula is: Copy Number = (Amount (ng) × 6.022×10^23) / (Length (bp) × 1×10^9 × 650).
Unit Conversion Details
To use the formula, convert all DNA amounts to nanograms (ng). For µg, multiply by 1000. For pg, divide by 1000.
Worked Example
Example: 5 ng of 3000 bp plasmid: Copy Number = (5 × 6.022×10^23) / (3000 × 1×10^9 × 650) = 1.54 × 10^9 copies.

Calculation Examples

  • 5 ng, 3000 bp: 1.54 × 10^9 copies
  • 100 pg, 50000 bp: 1.85 × 10^6 copies
  • 0.2 µg, 1500 bp: 1.24 × 10^11 copies (log10 = 11.1)
  • 10 ng, 25 bp: 3.71 × 10^11 copies